Carbon buildup.)
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DEQ/Department of Environmental Quality/Emission Testing and Repair/Smog Checks:
When DEQ fails a vehicle at their emissions testing facility, it's usually for one of three reasons: High emissions that have actually been measured; failed equipment as indicated by the check engine light (also called malfunction indicator light or MIL); or visible smoke. We have some of the most competent and experienced diagnosticians available to diagnose what your Toyota, Lexus, or Scion needs to pass DEQ.
The following DEQ checklist is a composite description that describes DEQ diagnostic procedures for vehicles with several generations of developments, including:
- Carbureted and fuel injected.
- With air-fuel ratio feedback (by way of O2 sensors and/or air-fuel ratio sensors) and without.
- Vehicles with catalytic converters and older vehicles without.
- Those with vacuum advance and mechanical advance and those that have electronically controlled timing.
- Ignition systems with distributors and distributorless ignition systems with ignition coils directly over the spark plugs.
- Vehicles with no onboard diagnostics built in; vehicles with first-generation onboard diagnostics that are accessed through jumper wires and blinking-light codes; and vehicles with second-generation diagnostics that are accessed through full computer hook-up.
Our DEQ testing procedures include any number of the steps listed below, not necessarily in this exact order:
- Test drive for drivability symptoms.
- Check for stored diagnostic trouble codes on vehicles equipped with onboard diagnostics.
- Check Toyota's online database to see if any bulletins have been published that apply.
- Check actual emissions if appropriate and compare to DEQ test results.
- Check various systems:
- If equipped, check air fuel ratio sensor to verify that it's giving credible signals that reflect changes of mixture that you impose on the system.
- O2 sensor, note whether:
- Active back and forth over mid range.
- If not, is computer responding to O2 sensor signal? Can quickly test by giving artificial signals (positive and negative) by passing battery voltage through your body to the computer through the O2 sensor circuit.
- Able to give full range of signal (nearly 0 volts when made lean, and nearly 1 volt when made rich).
- Can quickly register changes, from very lean to rich and back again.
- Check air/fuel ratio feedback operation.
- Are devices getting computer's switching signals?
- Are devices working?
- Air injection/suction system working?
- Check Vf1 voltage at idle and at higher rpm's. Voltage ranges from 1-5. Low voltage indicates computer compensating to make leaner, and high voltage indicates computer compensating to make richer. Mid range means no compensation needed. For OBII, check fuel trim.
- Check initial ignition timing
- Check advance systems: Mechanical, vacuum, or electronic
- Note whether it pings on test drive. (NOx related)
- Check EGR. (NOx related)
- Has vacuum signal to EGR valve when accelerating?
- If no, does vacuum modulator have pressure signal from EGR tube and a vacuum signal?
- Valve opens and causes engine rpm to drop significantly when given vacuum signal at idle?
- Valve doesn't stick open and cause a miss at idle? (HC related)
- Check Catalytic Converter
- Note emission readings at idle and 2500 rpms.
- Note how much readings flare up on transitions between rpms.
- Note how high HC readings go on a snap, full-throttle acceleration
- Note whether idle readings that improve initially after revving for awhile increase again after a few minutes of idling
- Note cat temp at inlet and at outlet. Should at least maintain temp, and preferably should increase.
- After cat is fully activated, note CO2 readings on a dead crank test. Should be 12% or better.
- Check for visible smoke when revving after prolonged idling as possible indication of oil burning.
- Pull a spark plug & check condition. (Worn or fouling?)
- Check appropriate tune items.
- Exhaust leaks? (Dilution)
- Retest emissions and/or components after work completed.
- Test drive car again after work completed.
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Diagnosis/Diagnostic Charges/Estimates
People sometime ask whether we give free estimates, when what they really mean is whether we will diagnose their Toyota, Lexus, or Scion for free. In answer to the question of estimates, sure, we provide free estimates. If you ask us the cost of a specific routine repair, we won't charge you to tell you. Regarding diagnosis, it depends. Sometimes we can simply step out into the parking lot with you and casually look at your car and tell you accurately what the problem is. In that case we are happy to have provided you with a diagnosis at no charge and without your being obligated to follow through with having us repair your vehicle. Sometimes we can provide a quickie but accurate diagnosis with a quick test drive, and we're often happy to do that at no charge. If, however, we have to have a technician spend time diagnosing it, which often involves his time, the use of special equipment, and access to his knowledge and judgement gained through years of experience, then yes, we charge for diagnosis.
It's not uncommon for people to mistakenly believe that our use of a computer eliminates the need for diagnosis. The computer is a wonderful tool that aids us in diagnosis. It's useful enough that we've spent thousands of dollars buying computers and keeping them updated, but a computer is still just a tool; it's not magic, and it doesn't know everything. We are still heavily reliant on the technician's knowledge, experience, and judgement. Depending on the complexity of the system, we will normally get permission to spend a range of time and money for our initial diagnostic time. Within that time we will do whatever we think will best further your purposes. Once we engage with it, it can go three ways. Best case scenario, we diagnose your problem and repair it.
Next best, but very common, we diagnose your Toyota and then call you up with a quote for the repair. At that point you can say yes or no, however you want us to proceed. Worst case, we get to the end of our allotted time and we still haven't come to a conclusion as to the cause of the problem. This worst case is unusual, but it's a real possibility that should be acknowledged. People often ask if we charge for diagnostic time. The answer is yes. They also ask if we still charge for diagnostic time if the agree to do the service or repair. The answer to that is that to the extent that the diagnostic efforts and the repair efforts overlap, the customer gets the full benefit of that overlap.
To the extent that diagnostic efforts and the repairs are separate, they will be charged for separately. So, for instance: If we have to disassemble something in order to tell you that it's defective, then we may already be half way through the labor required for replacement, and of course you'll get the benefit of that. But, if we diagnose something that doesn't require disassembly, then the repair is a whole new activity on top of the initial diagnostic time, and you'll be charged for each individually.
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Differential/Final Drive Service
Toyota doesn't have any recommendations as to whether to ever replace the gear oils for the final drive except in the case of severe use, in which case they say to replace it every 30k. Our belief is that the differential oil should be changed every 30,000 miles in order to avoid premature wear and costly repairs.
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Distributor O-Ring and/or Inner Seal
The distributor o-ring seals between the distributor housing and the engine to prevent engine oil from leaking out. As with other rubber seals, the rubber tends to get hard with age and to loose its resiliency. It becomes compressed as this happens and is no longer able to seal against the oil leaking past it. Since the distributor is at the top of the engine, everything below the distributor ends up getting wet with oil as well. As a result, after you repair the known leak (the distributor o-ring), and after cleaning every thing else below it that was wet, you often have come back and recheck it later to see if there are any further leaks.
The distributor's inner oil seal is to prevent oil from traveling from the engine through the distributor along its center shaft. Usually this can be resealed when it leaks. Some times the seal will have worn a groove into the shaft, in which case the entire distributor housing needs to be replaced. For many vehicles, the ignition coil is located in the distributor. When the inner seal leaks and it soaks a portion of the ignition coil which almost always results in the ignition coil body swelling and cracking wide open.
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Drive Belts (for the engine)
Your belts are important for cooling your engine, charging the battery, and maintaining ease of steering. Even your air-conditioning belt is important, in that if it breaks it can derail one of the other belts that is more immediately critical to your engine's wellbeing. If your belts are old and cracking, it's a good idea to replace them preemptively before they break.
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EGR (Exhaust gas recirculation) System
The EGR system is an emission control subsystem. It reintroduces a small amount of the exhaust gasses back into the intake manifold under certain circumstances in order to reduce the intensity of the combustion and lower peak combustion temperatures. This serves a couple of purposes: It decreases the creation of nitrogen oxides, which are a main ingredient of smog. It also slows the rate of combustion so that it is more likely to result in a controlled burn rather than a violent explosion that results in pinging.
When the EGR system isn't coming on properly (insufficient flow) it results in higher nitrogen oxide emissions and can also cause your engine to ping--that rattle you may have noticed at times on acceleration. Chronic pinging can lead to severe engine damage. When it's coming on too much or at the wrong times it can result in running rough or dying at idle, or sometimes surging at light throttle cruise.
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Emergency Brake/Parking Brake Cable
A binding park-brake cable can stick in the applied position and cause your rear brakes to wear out prematurely. Depending on how far it's driven while on, it may also heat up and ruin your rear brake drums, and even cook the hydraulic wheel cylinders, which can result in loss of brake fluid and decreased brake pedal engagement. On most Toyotas, the park-brake cable activates the automatic-brake adjusters. Consequently, if the cable is broken, the rear brakes get out of adjustment and become less effective. Even if you are mostly parking on level ground, it's a good idea to use the park brake regularly in order to keep the rear brakes in adjustment and to keep the self adjusters from seizing up due to lack of use.
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Engine Mounts
The engine mounts serve a couple of purposes. First of all, they serve to locate the engine in the proper place in the engine compartment and in proper relationship to other components. For front wheel drive vehicles, it keeps the engine and transaxle in proper alignment with the drive axles as you're accelerating and putting power to the wheels. For rear wheel drive vehicles, it they keep the engine from tipping forward and chopping a hole in the radiator with the fan. A second purpose of the engine mounts is to insulate the rest of the car and the passengers from the engine's vibrations. As the engine mounts get old and hard they tend to increasingly transmit vibrations that are felt by the passengers. Engine vibrations are also more likely to be felt if the car is involved in an accident where things get skewed so that the engine isn't quite in proper alignment and the engine mounts are under tension. Some engine mounts have a fluid portion of their core, and if the fluid leaks out and the mount collapses as it ages, then this will result in more vibrations being passed on to the rest of your Toyota, Lexus, or Scion as well.
Every time you accelerate, the engine tries to twist out of position and rotate in the opposite direction that the wheels are rotating (front wheel drive cars) or the opposite direction that the driveline is rotating (rear wheel drive vehicles). Eventually the mounts may tear loose as a result of the cumulative stresses. When they do tear loose (or collapse with the fluid filled mounts) it allows the engine to lift up and shift around quite a bit more than normal. When this starts happening, it's not unusual to feel a clunk every time you're on and off the gas when in first gear. If you open the hood and have someone put it in gear and briefly accelerate while holding their foot on the brake you can see the engine lift up and then settle back down each time they're on and off the gas.
A broken engine mount doesn't result in your engine falling out on the road. It will result in extra movement, which puts other surrounding components under more stress. The remaining engine mounts will be under more strain and will be more apt to tear as a result. Hoses and electrical harnesses-every thing that bridges between the engine and the surrounding engine compartment will be repeatedly flexed more than they were designed to withstand, with the possibility of being fatigued until they break. The axle constant velocity joints will be under greater strain as they are operating out-of-position at greater angles than intended. The bushings that the axles engage with in the final drive portion of the transaxle will experience greater sideways pressure and be more apt to wear. The air intake tube that pipes air from the air filter housing to the throttle body of the engine is far more likely to crack and split open. I've never personally seen this, but in certain cases it can cause unintended acceleration if the engine shifts in such a fashion as holds the throttle open.
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Engine Oil Leaks
Oil from leaking seals and gaskets tends to move down, due to gravity, and toward the back of the engine, due to the airflow past the engine. Because of this it's not unusual that everything beneath a leaking seal will be wet, and although you know that the leak at the top and/or front of the engine is leaking, everything below it or behind it may or may not be leaking. Often the only thing that can be said for sure about the other wet areas is that they are in fact wet. For this reason, we recommend fixing the known leaks, and then cleaning the engine to establish a clean slate. After this, come back in for a future inspection after the car has been driven long enough for a leak to show itself, but not so long that everything could be so broadly wet as to obscure the source of the leak.
See Engine oil seals.
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Engine Oil Seals
If you have leaky engine oil seals, the at minimum you should be sure to regularly check your oil level to avoid damage to the engine for lack of oil. However, even with slow leaks there is good reason to repair them. Often, oil leaks are a result of seals that have gotten hard with age. These hardened seals tend to wear a groove into the sealing surface, which increases the likelihood that the metal sealing surface will need to be repaired as well. An additional concern is that adjacent rubber components like coolant hoses and suspension bushings will be damaged and significantly weakened by exposure to the oil.
These weakened coolant hoses tend to bloat and eventually become much more likely to split under pressure from the cooling system and invite damage to the engine from loss of coolant. On a personal note, when I was a kid I had engine that was leaking oil and I ended up having to overhaul it because I didn't stay on top of it closely enough. Later on, I had another oil-leaker that I was "staying on top of" till I lent it out to a friend for an extended period while I was out of the country. This engine ran out of oil and had to be rebuilt as well. Oh well, live and learn.
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Engine Oil Service
Faithfully changing your Toyota's engine oil is one of the least glamorous, but most effective steps you can take to insure that your car has a long and happy life. Our recommendation is to replace your engine oil and filter every 3000 miles. At this time we also inspect it for any other needs that may have developed in the interim.
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Engine Oil Sludge
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Engine Pan Gasket:
The engine pan is where the oil pools when it's not being circulated through the engine. Most of the Toyota engine pans are sealed pretty well so that they don't leak very often. Tercels, Paseos, and older Land Cruisers are an exception to this. Other models pan gaskets can leak as well, but with all of them, the first thing you want to be sure of is that something else isn't leaking from above and catching on the edge of the engine pan and making it look like it might be leaking.
Even "non-leaks" can result in the edge of the engine pan collecting oil and looking like a possible leak. For instance, every time your oil is changed and the oil filter is removed—unless someone is darned thorough in their clean-up—most likely a little bit of the oil that spills from the oil filter dribbles down to the edge of the engine pan. Once there, it tends to migrate around the entire perimeter, making it look for all the world like it could be leaking. Rule of thumb, unless it's so definite that it's obvious, it's not a bad idea to clean wet area and then re-inspect it before jumping in to replace the pan gasket.
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Engines-used
See Used parts/engines/transmissions and Low mileage Japanese engines
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Exhaust Flange Gasket:
This is the gasket that seals between the exhaust manifold and the header pipe. See Exhaust system leaks for further discussion.
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Exhaust Manifold:
The exhaust manifold goes through extreme temperature changes, which can eventually cause it to warp and/or crack. When they warp, sometimes it results in the manifold adding so much pulling force that the studs that secure the manifold to the head strip the threads out of the aluminum head. See Exhaust system leaks for further discussion.
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Exhaust System Leaks
Some people view exhaust system leaks mainly as an aesthetic issue; they simply don't like driving with a noisy exhaust system. It can pose a health risk if the exhaust leak is getting into the car. This is especially likely during periods of prolonged idling in slow traffic. (Incidentally, you are also breathing exhaust from the cars around you if you have your heater/air conditioner intake set to fresh air.) If the exhaust leak is sufficient, it can cause DEQ to fail your car due to their getting a diluted exhaust sample.
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Final Drive/Differential Service
Toyota doesn't have any recommendations as to whether to ever replace the gear oils for the final drive except in the case of severe use, in which case they say to replace it every 30k. Lexus, their sister company, recommends that the gear oils be changed every 30k. Toyota does say to inspect it every 15k. The fluid clearly degrades with use over time, changing from nearly clear or very light amber to black. It's consistency changes over time as well. Our belief is that the differential oil should be changed every 30,000 miles in order to avoid premature wear and costly repairs.
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Flush Brake Hydraulic Fluid
See Brake hydraulic fluid flush.
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Fuel Filter
Toyota, Lexus, and Scion don't have any written recommendations on when your fuel filter out to be replaced as an act of preventative maintenance. A fairly common industry practice is to replace them every 30k. The Toyota dealerships that I'm familiar with used to go by this practice as well.
Sometime in the 90's Toyota had a problem with their manufacturing plants over tightening the fuel lines to the fuel filters. The result was that when replacing the fuel filters, some of the fuel lines had threads that were damaged to the point that the entire fuel line had to be replaced. For a couple of years Toyota Motor Corporation covered these fuel lines under warranty, and then one day they said "Hey, we never told you to change those filters in the first place-they're lifetime fuel filters." At that point, the dealers that I'm familiar with stopped replacing the filters as an act of routine maintenance. While it's true that the fuel filters are in fact long-lived, it still stands to reason that anytime you have something that is constantly acting as a filter, eventually the filter will get clogged up.
Even if gas is always completely free of any contaminants that might need to be filtered out before they reach the injectors, even in this case the filter can become clogged. This is true because the same chemicals that come out of solution and eventually restrict the injectors can also come out of solution and eventually plug up the fuel filter. When that happens, you still end up having to pay to replace the fuel filter, but now you also have the added expense of diagnosing the problem, plus the added inconvenience of an unplanned for visit to the shop for the repair.
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Fuel Pump
The fuel pump needs to be able to provide fuel at sufficient pressure and volume to run the engine over a wide range of rpm's and loads. A check valve in the fuel pump should be able to maintain some line pressure after the engine is shut off. This reduces cranking time on restarts. It also reduces the likelihood of rough running on initial hot start-up after having sat with a hot engine for awhile. Keeping it under some pressure raises the temperature at which the gasoline boils.
In Oregon, the gasoline all has at least 10% ethanol alcohol, which lowers the boiling point. When it boils, it creates vapor pockets, which tend to make the engine start harder and then run rougher when restarted after sitting hot. Even with everything in order, sometimes cars will have some rough running on initial hot restart for perhaps 10 to 20 seconds, especially since the gas has ethanol in it year round now. This is made worse, of course, if the fuel pump isn't maintaining pressure to suppress the boiling.
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Gear Oil Service
Toyota doesn't have any recommendations as to whether to ever replace the gear oils for the various gear boxes (manual transmission, transfer case, and differentials) except in the case of severe use, in which case they say to replace it every 30k. Lexus, their sister company, recommends that the gear oils be changed every 30k. Toyota does say to inspect it every 15k. The fluid clearly degrades with use over time, changing from nearly clear or very light amber to black. It's consistency changes over time as well. Our belief is that the gear oil should be changed every 30,000 miles in order to avoid premature wear and costly repairs.
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General Inspection, Prepurchase Inspection, Pre-Trip Inspection:
I strongly encourage people to have a general inspection done prior to buying a used vehicle. Doing so doesn't tell us infallibly whether the vehicle is going to be trouble-free or not, but it gives us a good broad picture of the vehicle on which to base a reasonable decision regarding it. People have us do this same sort of inspection prior to going on major trips. They also have us do this inspection to determine the state of their existing vehicles in order to establish a game plan for maintenance and repairs. Sometimes this inspection reveals that it might be good to disconnect entirely from a vehicle you already own.
When buying a used vehicle, here's a little trick that you can perform yourself before paying us to do a full-on inspection. A lot of engines that burn oil will show smoke only during certain conditions. One of the conditions is when being accelerated after prolonged idling. Warm the vehicle up, and run it for maybe ten minutes at idle after it's warm. At that point, give the engine a good aggressive acceleration and look to see it there is any significant amounts of blue smoke coming out the exhaust. If there is, the engine burns oil, and you probably don't want to buy it.
And, you've just saved yourself the expense and trouble of a full inspection. Note: If someone has put extra heavy oil in the engine, then this test may not reveal what you want. I once did a prepurchase inspection on a car that checked out good, including the test for smoke after prolonged idling. The customer bought the car and had us do an oil change directly. Apparently the seller had installed thicker than standard oil, because the engine began smoking as soon as we put in the standard 10w30 oil. Rats. So here's my admonishments to you: First of all, don't you be evil in your dealings with others. And, while my impression is that lots of people are wonderfully honest in how they sell their cars, some aren't, and even those that are honest may be ignorant of the true condition of the car they're selling. So, secondly, do due diligence to protect your interests before you buy the vehicle.
We don't routinely perform a compression check during the above inspection. We will perform a compression check if the customer simply wants us to in order to cover all the bases. Or, if something about the vehicle causes us to think that a compression check would be useful, then we'll suggest we do it. In either of these instances the compression check is an additional cost over the basic general inspection.
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Head Gasket
The head gasket serves to seal off the combustion chambers and the cooling system from each other and also from the rest of the world. An early sign of internal failure is an invisible loss of coolant that doesn't appear to be a result of any external leaks. In this case the coolant enters into the combustion chamber and passes out the exhaust.
As it gets worse, it will be accompanied by excessive white steam out the exhaust, and you may also notice that the engine seems to run rough with a misfire on initial startup after sitting. If enough coolant accumulates in the cylinder while sitting it can even result in a "hydrostatic lock" where the engine can't crank due to the fact that the coolant can't be compressed. A blown head gasket can be detected at a shop by using an exhaust analyzer to sniff the cooling system for HC's (unburned hydrocarbons) that are there as a result of exhaust from the combustion forcing it's way past the head gasket and into the cooling system.
A blown head gasket can result in overheating, both from loss of coolant and from the cooling system being made less efficient due to the exhaust gasses interrupting the flow of coolant through the engine. Alternatively, a good head gasket can be blown in relatively short order due to excessively overheating the engine as a result of some other cause, such as loss of coolant from some other leak, a bad thermostat, a restricted radiator, a bad water pump, or a broken water pump drive belt.
When the head gasket is blown as a result of overheating, the cylinder head is quite commonly warped at the same time. In addition to head gasket failure resulting in damage to the engine through overheating, it also risks scoring and damaging the cylinder walls as the mix of antifreeze and water strip the lubrication from the cylinder walls. This can result in the engine burning oil, as the rings are no longer able to keep the oil from slipping between the rings and the cylinder walls. If you suspect that you may be experiencing a head gasket failure, I encourage you to have it checked and repaired directly, as delayed action may eventually result in catastrophic engine failure.
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Idler Arm
The idler arm is part of the steering linkage in vehicles with parallelogram-steering linkage. Vehicles with rack and pinion steering don't have idler arms. When all of the steering linkage components are in good order, it allows the driver to have relatively precise control of the steering over a wide variety of speeds and conditions.
As the idler arm wears, it allows extra play, so that the wheels can wag back and forth-pointing in or out-independently of the driver's intent. This causes the car to wander more, and results in the driver to having to more actively manage the steering. In instances of advanced wear, sometimes the steering will start shaking violently after encountering a sharp jolt (as when going over rail road tracks quickly) and will continue to shake until the vehicle is slowed down significantly.
Although in the early stages this wear isn't an urgent issue, it can become a safety hazard as the wear becomes more severe. Aside from the safety issue it poses, it also encourages premature tire wear, as the wheels are no longer held in proper alignment when they are allowed to wander uncontrolled like this.
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Inspection
See General Inspection
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Low mileage Japanese engines
I can't know what the actual reality is regarding these supposedly low-mileage engines that get imported year after year, but I'm skeptical as to how they're represented.
- First of all, it has never struck me as credible that the Japanese government's regulations are such that it requires their citizens to sell us their engines at a low price when they hit approximately 30,000 miles.
- Secondly, the engines I've seen with their hard seals and such didn't have the appearance of being low-mileage engines.
- And finally, there's the issue of being unable to control the final outcome to be a good outcome. The last engine I installed (years ago) ran on about two and a half cylinders out of four. Who's ever heard of a Toyota engine doing that with 30k on it? We called up the suppliers, and they said, "Oh, no problem. Just send the engine back to us and we'll send you another one." It may have been no problem for them, but it was a particularly labor intensive installation in and older Van and a significant setback for us. I decided that they couldn't control whether they were sending us good engines. This was further confirmed in that they weren't confident enough in their product that they would warranty our labor if they sent us a bad engine. That being the case, I'm not willing to take part in the gamble with them when the risk is entirely on our customers and us.
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Maintenance-Required Light
This light comes on to remind you to change your oil. It comes on 5,000 miles after the last time it was reset. It comes on strictly as a function of those miles-it has no way of knowing whether your oil has or hasn't been changed in the interim-and it never, ever is an indication of something being wrong. Sometimes shops neglect to reset the maintenance-required meter if the light doesn't happen to be on yet when they are changing the oil. Many quick-lube shops simply don't know how to reset it.
The maintenance-required light is easy to reset. On most Toyotas you simply:
- Turn the key to the on position.
- Determine that the odometer reading is displayed. (For some models, it's the trip-meter "A" that you want to be displaying.)
- Turn the key back off.
- Push and hold the reset button for the trip meters. (Same button as used to navigate between the odometer and the two trip meters.)
- While continuing to depress the reset button, turn the key back to the "on" position, but not so far as the "start" position. The odometer display should come up with a series of dashes that disappear one by one. When they've all disappeared, a series of zeros will display. Continue holding the reset button until all of the zeros clear and the odometer (or trip meter "A") reading returns.
The maintenance-required light should be off, and the vehicle will now be counting toward the next 5,000 interval, at which time it will turn on again.
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Manuel Transmission Service
See Gear Oil Service
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Muffler
Some people view exhaust system leaks mainly as an aesthetic issue; they simply don't like driving with a noisy exhaust system. It can pose a health risk if the exhaust leak is getting into the car. This is especially likely during periods of prolonged idling in slow traffic. (Incidentally, you are also breathing exhaust from the cars around you if you have your heater/air conditioner intake set to fresh air.) If the exhaust leak is sufficient, it can cause DEQ to fail your car due to their getting a diluted exhaust sample.
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O2 Sensor/Oxygen Sensor
See Oxygen Sensor
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Oil Cooler Seals
See (Engine Oil Seals and Engine Oil Leaks)
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Oil Filter (Toyota Vs. Non- Toyota)
Years ago I worked for an independent shop that specialized exclusively in Toyota repairs. At one point the owner wanted us to consider using non-Toyota oil filter because he could buy them for less money. We cut open the non-Toyota filter that he was considering, and compared it side-by-side to a Toyota filter that we also cut open. In this instance, there was no question in our mind that the Toyota filter was superior in two very visible counts.
First, it had an anti-bleed-back check valve, which meant that the oil filter was less likely to drain down between uses, and meant that the engine would achieve full oil pressure more immediately on initial start-up. Delayed oil pressure leads to more rapid wear of expensive engine parts. Secondly, the Toyota filtering element was folded in such a fashion that it had far greater surface area in the same sized filter canister than the non-Toyota one had.
This doesn't mean that no one in the world is making a filter that is equal to or even perhaps superior to the Toyota filter. But clearly the Toyota was a high quality oil filter-on the one hand, far superior to some of the aftermarket alternatives, and on the other hand, reflective enough of Toyota's high standards for quality that we weren't particularly motivated to do a search for something that might in some fashion surpass it for some supposed gain that would likely be minimal at best.
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Oil Pressure-Sending Unit
The oil pressure sending unit was triggers the warning light when the oil pressure gets dangerously low, or, it activates the oil pressure gauge if you have one. If it's leaking oil, it's a good idea to replace it in order to protect your engine against damage from loss of oil. (See Engine oil seals and Engine oil leaks for additional comments.)
If it's not giving you a valid oil pressure warning signal, then it's important to replace it so that you can trust it to adequately warn you in time to avoid engine damage from loss of oil pressure. In the case of the warning light, you can verify that it's even able to give you a warning signal by checking to see that the light comes on when you turn the key to the "on" position without actually starting the engine. At this point, there's no oil pressure, but the key's on, so the warning light should turn on. If you start the car, it should turn off almost immediately.
See Engine oil seals and Engine oil leaks for additional comments.)
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Oil Pump Seals
If your oil pump seals are leaking, then at minimum, you should be sure to regularly check your oil level to avoid catastrophic damage to the engine for lack of oil. However, even with slow leaks there is good reason to repair them. Often, oil leaks are a result of seals that have gotten hard with age. These hardened seals tend to wear a groove into the sealing surface, which increases the likelihood that the metal sealing surface will need to be repaired as well. This is a fairly common problem with oil pumps on engines with higher miles. (See Engine oil seals and Engine oil leaks for additional comments.)
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Oxygen Sensor/O2 Sensor
The oxygen sensor is constantly sniffing the exhaust and sending the computer a fluctuating signal where it says in effect "a little more gas" and then "a little less gas." If it gets sluggish so that it's slow to update it's report, then it might get stuck saying "more, more, more-oops-less, less, less." A sluggish O2 sensor can cause your idle to hunt where the rpm's wander up and down a bit. It can also cause some surging feel when driving at lower speeds with light-throttle acceleration or light-throttle cruise. A properly working O2 sensor is needed for fuel economy, for clean emissions, and your basic engine performance.
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Pinging
Pinging is a rattle you hear on acceleration. It sometimes is a little erratic sounding-the sound is reminiscent of when you shake a can of spray paint that has the rattle ball in it. It's also reminiscent of the noise you hear when you lug the engine by trying to accelerate while in too high a gear.
Light and intermittent pinging is harmless, and in fact, for years Toyota has specifically mentioned in owner's manuals that light and intermittent pinging is acceptable. Chronic, heavy pinging can lead to severe engine damage. There are a number of factors that can lead to pinging: Lean-running conditions, a malfunctioning EGR system, over-advanced ignition timing, carbon buildup in the combustion chambers, and gasoline with an octane that's too low for your particular engine.
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Pinion Seal/Differential Pinion Seal
The differential takes the power from the drive shaft and sends it to the axles to power the wheels. The pinion seal is an oil seal at the point where the power enters the differential. Obviously, if it's leaking significantly, you run the risk of ruining your differential gears and bearings if it runs low on oil. However, even with slow leaks there is good reason to repair it. Often, oil leaks are a result of seals that have gotten hard with age. These hardened seals tend to wear a groove into the sealing surface, which increases the likelihood that the metal sealing surface will need to be repaired or replaced as well.
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Pitman Arm
The pitman arm is part of the steering linkage in vehicles with parallelogram-steering linkage. It's the active member at the opposite end of the linkages from the idler arm. Vehicles with rack and pinion steering don't have pitman arms. When all of the steering linkage components are in good order, it allows the driver to have relatively precise control of the steering over a wide variety of speeds and conditions. As the pitman arm wears, it allows extra play, so that the wheels can wag back and forth-pointing in or out-independently of the driver's intent.
This causes the car to wander more, and results in the driver to having to more actively manage the steering. In instances of advanced wear, sometimes the steering will start shaking violently after encountering a sharp jolt (as when going over rail road tracks quickly) and will continue to shake until the vehicle is slowed down significantly. Although in the early stages this wear isn't an urgent issue, it can become a safety hazard as the wear becomes more severe. Aside from the safety issue it poses, it also encourages premature tire wear, as the wheels are no longer held in proper alignment when they are allowed to wander uncontrolled like this.
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Power Steering Hoses
Power steering hoses can eventually leak. The high-pressure hoses have to be able to hold up to 2000 pounds per square inch. We don't routinely replace these by any mileage, but only replace them on an as-needed basis. They usually less labor if done at the same time the power steering pump is being removed to reseal. Some of the Toyota hoses are phenomenally expensive. Some years ago we took some leaky high-psi hoses and sent them out to be reconstructed. That only lasted maybe a year and a half-or perhaps two at the very most-and things didn't line up quite right for reassembly. We ended up deciding against that route for the future. So, we continue to use the hoses from Toyota, because we get the best, most reliable results that way.
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Power Steering Pump
Far and away most often we repair the power steering pumps rather than replace them, and usually that's a matter of resealing them. When they do need replacing, we insist on using Toyota power steering pumps. I've just seen too many poor quality alternatives. As a side note, it's not an uncommon strategy for some aftermarket suppliers to offer a lifetime warranty on their products. This is strictly a marketing tool and has no relationship to the quality of their product. Over and over I've met people who have gotten stuck with poor quality parts that repeatedly fail prematurely, and eventually they get worn out with doing repeat repairs and decide that the better quality Toyota part is the better deal after all.
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Power Steering Pump Reseal
When the power steering pump gets low on fluid it makes a droning/groaning noise, especially when steering. When the power steering pump is leaking, in most instances a cost-effective solution is to reseal your existing pump. Given that the pump is performing correctly and quietly when it's full of fluid, we feel completely comfortable disassembling it and installing a complete set of new seals-both inner and outer. We prefer resealing your original Toyota power steering pump rather than replacing it with an aftermarket rebuild. Years ago I worked for a shop tried aftermarket rebuilds for awhile, and after we replaced the pump on one car 3 times in about 2 weeks. And, of course resealing your existing pump saves quite a bit of money over buying a new pump from Toyota. When your pump and/or power steering hoses are leaking, at minimum you want to keep the level full. The more often it runs low, the more likely you are to damage either the pump or other components like the power steering rack or the power steering gear. Again, most pumps can be resealed, and we feel completely comfortable doing so.
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Power Steering Rack
Toyota's power steering racks tend to hold up pretty well. The commonest reason for failure is that eventually the seals start leaking fluid. In this case (with an external leak) the power steering still works, but you're losing your power steering fluid to the ground. Occasionally the valving will fail in such a way that power steering is lost in either one or both directions. When they do fail, I strongly prefer to replace them either with one provided by Toyota, Lexus, or Scion, or from the suppliers that provide for Toyota, Lexus, and Scion. New or remanufactured—either way's fine by me—but I've seen to many short lived aftermarket power steering racks to want to go the aftermarket route.
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Prepurchase Inspection, Pre-trip Inspection
See General Inspection
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Radiator
The radiator is part of the cooling system, which is supposed to be a contained system. As the radiator ages it can may fatigue and begin to leak through cracks that develop, or, it may rot from the inside out and develop pinholes. If it's a significant leak, it needs to be dealt with directly. Sometimes at the early stages when the leak is only at a level of minor seepage, people will monitor the coolant level and live with it till it's progressed to a more significant rate of loss.
However, loss of coolant can cause catastrophic engine failure due to overheating. If you have any known leaks in the radiator, then at minimum, you should regularly check your car's coolant level and keep a careful eye on the temperature gauge. Due to the possible serious consequences of any lapse in your vigilance, it's probably best to simply perform the needed repairs. Radiators can also fail due to clogged, restricted passages. When this happens, the coolant isn't able to flow through the radiator at a sufficient rate to cool the engine. This results in the greatly increased likelihood that your engine will overheat on hot days or when going up hills. If you know that your radiator is plugged up, you should treat this a s high priority repair.
When checking your coolant level, check both the plastic overflow reservoir and the radiator itself. As the coolant heats and expands, some of it goes into the overflow reservoir. As it cools and contracts, it is supposed to be sucked back into the radiator. It's no good just checking the overflow, because if the cooling system isn't sucking the coolant back into the radiator properly, it's possible to have a full overflow and an empty radiator. You want both levels to check out right, but of the two, the coolant in the radiator is the coolant that's actively involved in cooling the engine; this is the coolant level that's most critical to be full. Check coolant levels when engine is cool to avoid risk of being burned by hot coolant coming out of the radiator under pressure.
Note: We have a real aversion to the use of chemicals put into the cooling system for the sake of stopping leaks from the inside out. These chemicals purport to plug up the leak, which sometimes they do for awhile, but they also tend to plug up cooling passages with the result that the engine can overheat and develop worse problems that are far more expensive, like a blown head gasket. Stop-leak additives can also cause the heater core passages to get plugged up, which results in your heater not heating properly.
Radiator Stop-leak
See note at bottom of Radiator or Cooling system leak sections.
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Radiator Stop Leak
See Note at bottom of Radiator Section
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Shock Absorbers & Struts
See Struts & Shock Absorbers
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Sludge
See Engine Oil Sludge
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Spark Plugs & Ignition System
When I first started working as a mechanic I kept hearing older technicians say that it was important to use factory ignition parts in general, and factory spark plugs included in that. My first take on this was that it was probably just a case of mechanic superstition-I thought surely any manufacturer in the industry could make good spark plugs.
Over the years, however, I've seen too many instances where people have gone from shop to shop spending hundreds of dollars trying to fix a drivability problem "that couldn't be due to the spark plugs or the rest the ignition system because all of that was new," and yet the problem would trace exactly to those aftermarket parts and be resolved with the installation of factory, original Toyota supplier parts.
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Spark Plug Tube Leaks
Many of the Toyotas have semi-hemispherical shaped combustion chambers that result in the spark plug being placed straight down through the top of the head. In these instances, the spark plug enters the combustion chamber at the bottom of a spark plug tube that passes through the valve cover and valve area. If this tube begins to leak, it usually results in very little measurable loss of oil, however, as this small amount of oil floods the spark-plug tubes, it will eventually ruin your ignition wires and cause an engine misfire as they start shorting out.
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Struts & Shock Absorbers
A properly functioning suspension system allows your car to drive comfortably and safely at relatively high speeds even when going over bumps and irregularities while simultaneously cornering on a wet road. The struts and shock absorbers are important both for comfort, safety, and maintaining the integrity of the surrounding components. At relatively slow speeds bad struts and shocks seem mostly an aesthetic/comfort issue. Most people don't enjoy the jouncey ride with the vehicle swaying and bobbing every time you change lanes or corner, accelerate, brake, or go over a bump. At higher speeds though, it increasingly becomes a safety issue. Struts and shock absorbers control the springs so that the springs aren't allowed to go into uncontrolled oscillations and bouncing. When the spring action isn't being controlled through the shock absorption system, the tires are trying to hop and they don't maintain continuous and effective engagement with the road. This can be particularly dangerous in an emergency situation when you need all the traction you can get and where you are trying to turn and brake at the same time on a road with an irregular surface.
In addition to the comfort and safety concerns, when the struts and shocks get weak, the vehicle's suspension is much more likely to be bottoming out so that components hit the end of their range of travel with damaging force. We've seen instances where the shocks or struts rip loose from their attaching points (creating extra damage and cost) due to prolonged hammering experienced from driving after they were weak and ineffective.
Weak and ineffective struts and shock absorbers also contribute to premature tire wear.
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Thermostat
The thermostat helps regulate your engine's temperature. Thermostat failure can cause your engine to run either too cold or too hot. Too cold will cause a loss of gas mileage, reduced heater performance, and increased engine wear. Too hot can cause sudden engine failure, such as a blown head gasket.
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Tie-Rod Ends (inner and outer)
The tie-rod ends are part of the steering linkage. As they wear, you may notice a clunking at times as you drive and encounter various irregularities in the road. When all of the steering linkage components are in good order, it allows the driver to have relatively precise control of the steering over a wide variety of speeds and conditions.
As the tie-rod ends wear, it allows extra play, so that the wheels can wag back and forth-pointing in or out-independently of the driver's intent. This causes the car to wander more, and results in the driver to having to more actively manage the steering as it becomes more approximate. This also encourages premature tire wear, as the wheels are no longer held in proper alignment and are allowed to wander.
For most of your normal driving circumstances the problems presented are no more urgent than indicated above-although it results in increased tire wear, moderately worn tie-rod ends aren't going to make your wheels suddenly fall off, and they're not going to make you suddenly dart into a ditch. However, in an emergency situation that involves braking and turning and dodging others all at the same instant and when your needing all the control you can get-you want all the control you can get to avoid a possible accident. In those situations, it's nice to have the steering system doing exactly what it's supposed to be doing, and the wheels pointing exactly where they're supposed to be pointing. Right?
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Timing Belt
Timing belts are rubber, and age based on time and mileage. They can also be damaged by oil fouling due to oil leaks, or by the failure of other parts as in the case of when water pumps or timing belt bearings seize up. Timing belts usually give very little warning before they fail, although some of the 4-cylinder engines that don't have a dynamic tensioner will give a characteristic rattle as they get loose with age. Typically, this timing-belt rattle can be heard best at idle and just off idle when the car is first started up cold.
If your timing belt breaks, your car's engine will stop running. Although most Toyota engines are unharmed by timing belt failure, it's impossible to predict whether you will be put in harm's way, or what level of inconvenience you will experience due to timing belt failure while driving.
This type of repair is best handled as a matter of routine preventative maintenance. If your timing belt is due to be replaced, I encourage you to call us today for an appointment and avoid the risk of unnecessary inconvenience or expense. See also Timing belt contingencies.
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Timing Belt Contingencies
When quoting a timing belt replacement, there are a number of contingencies that will be unknown until we're well into the job. For instance, the timing belt bearings may still be functional and essentially symptom free. However, once the timing belt has been removed, we can spin the bearings while feeling them and listening to them. If a timing belt bearing is beginning to sound worn-or even just dry, as if it's lost its lubrication-then that's the time to replace it while it's so accessible that there's no labor required. On the other hand, if the timing belt bearings feel and sound good, we feel completely comfortable reusing them.
We also check the drive belts. Of course these can typically be assessed before any work has begun. The drive belts tend to last longer than the timing belt, but not nearly as long as two timing belt lives. If the drive belts are the same age as the timing belt, it's probably not a bad idea to just go ahead and replace them preemptively while they're off even if they're in decent enough condition that you wouldn't otherwise need to replace them.
As far as the water pump goes, some of our recommendations are contingent on the vehicle. For instance, the 3 liter and 3.4 liter V6 engines in the trucks and 4Runners have such a history of leaking that it seems like a good idea to replace them preemptively even if they don't show any signs of leaking. On the other hand, the water pumps on the 1MZFE V6 engines in Camrys and Siennas have such a good record of longevity that I don't feel at all uncomfortable if a customer is inclined to reuse one of these for another timing belt life cycle. Of course anytime a water pump is actually showing signs of failure, if its eventual replacement is dependent on removing the timing belt, then by all means replace it while the timing belt is off.
The front engine oil seals-for the crankshaft, the camshafts, and the oil pump-are all accessible while the timing belt is off. If any of these are leaking, then I most often advise that they all be replaced at the same time since the rubber seals have all had the same number of miles and years to age. I used to never suggest these seals be replaced preemptively, but I have a growing bias toward replacing them. Although sometimes they make it through a second timing belt life cycle, too often they won't successfully make it through the duration without leaking oil and you'll end up having to pay to remove the timing belt again to access to the seals.
Sometimes the seals have gotten hard and will have cut a groove into the sealing surface. In this case, we need to install a seal-surface repair sleeve in order to assure that the new seal is able to engage and seal properly. This grooving can happen to any of seal surfaces that involve a shaft rotating past a seal. It happens more frequently to the crankshafts than to the camshafts, because the crankshaft turns at twice the speed of and twice as many rotations as the camshafts. When the grooving happens to the oil pump gear shaft, then the oil pump gears need to be replaced, which typically isn't a very expensive part.
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Timing Chain
The timing chain connects between the crankshaft-at the bottom of the engine-and the camshaft-at the top-to keep the two operating in synch with each other. As your timing chain wears, it gets loose and begins to slap against the guides. Eventually the one of the guides breaks, and then the chain starts slapping against the inside of the timing cover. This produces a characteristic rattle. If it continues, the chain eventually cuts through the timing cover and into the back of the water pump area, which causes a major exchange of oil and water that often results in damaged engine bearings.
Alternatively, sometimes the chain will break and fall off the gear that it turns to operate the valves, and the valves will be ruined when they are hit by the pistons. In either case, the cost of the repair goes up significantly. By far, your best course of action is to replace your timing chain prior to that stage of wear. In my early experiences with timing chains, usually when pieces of the guides broke off they fell harmlessly into the engine oil pan and didn't create any problem. As a result, if the owner was of a mind to, I felt pretty relaxed about watching the wear progress even to the point of the guide breaking entirely off.
However, in the years since I've seen that the pieces of guide don't always fall harmlessly into the engine pan. Sometimes they fall between the crank gear and the timing chain, at which point with each revolution the chain gets hiked over another tooth, and in a very brief moment you've got multiple bent valves. In this event, the head has to be overhauled in addition to replacing the timing chain assembly. As a result of seeing this, plus the odd instance when the chain simply breaks, I now feel that it's far more prudent to take the earliest indications of a worn chain and simply act on that basis to replace it. Otherwise, the longer you wait, the more you increase the odds that the final repair will be as much as two and a half times as much as what it would have been if you'd acted on it more promptly.
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Tires
I don't have a lot of detail to offer on various tire decisions, but I'll share my preferences here. I want all season tires with rubber that has maximum ability to grip the road. This is more important to me than maximum tire life, and it's more important to me than maximum fuel economy.
Slightly harder tires tend to wear longer and provide better fuel economy. Slightly softer tires tend to grip the road better. I know that most of the time I won't be in those near emergency situations that require the very best traction available, but when I'm in those situations, I want to come out alive and hopefully unharmed, and for me, that's worth sacrificing a little fuel economy and tire longevity. I always ask for tires with the best friction rating.
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Transmission Pan Gasket
Because of the manner in which we flush automatic transmissions, we don't routinely have the pan off nor need to replace the pan gasket as part of the transmission service. There is, however, a small amount of labor overlap between the two. If your transmission pan gasket is leaking, it's a little more economic to combine the flush and transmission pan gasket into one repair than it would be to do both items but separately on different occasions.
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Transmission Case Service
See Gear Oil Service
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Transmission Service (manual transmission)
See Gear Oil Service
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Transmissions-used
See Used parts/engine/transmissions
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Toyota parts versus aftermarket parts
Toyota makes good parts, and that's what we want to use. Our biggest supplier of parts is a Toyota dealership. Our next biggest supplier is a company that sells us the same parts that were made by the original Toyota parts suppliers. The result is that the vast majority of the parts we use either come from Toyota direct (through a dealership) or from the original suppliers of the Toyota parts. To give you an example, Nippon makes Toyota's fuel filters. The Nippon fuel filters look identical to the Toyota filters, and in fact, if we care to peel off the strip of black tape that Nippon has applied to the filters they sell us, underneath the tape is the original Toyota parts sticker with it's Toyota part number. It's the exact same part whether we buy it from Toyota or from Nippon. Same way with clutches. A company with the name Aisin/Asco makes clutches and water pumps for Toyota. They used to sell those same parts to us new, in a Toyota box, at a price competitive with the same thing remanufactured from Toyota. There wasn't any question in my mind-I preferred the new to the remanufactured. Since then, Toyota has prevented them from selling those parts in Toyota packaging, but the parts still have all of the same casting marks and look identical, except the water pumps have had the word "Toyota" ground off and replaced with other company markings.
Again, I have a strong preference for Toyota parts. I've just seen too many poor quality alternatives. As a side note, it's not an uncommon strategy for some aftermarket suppliers to offer a lifetime warranty on their products. This is strictly a marketing tool and usually seems to have no relationship to the quality of their product. Over and over I've met people who have gotten stuck with poor quality parts that repeatedly fail prematurely, and eventually they would get worn out with doing repeat repairs and decide that the better quality Toyota part was the better deal after all. Other times the life-time warranty was handled in such a slippery fashion and it was so difficult to manage their way through the hurdles set before them that the life-time warranty was effectively a lie.
See also Air Filters, Catalytic Converter, Oil filter (Toyota versus non-Toyota) and Spark plugs & ignition system for discussion as applied to specific parts.
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Tune & Tune Checks
People have an incredibly wide range of perceptions as to what a tune-up entails. Both among consumers and shops, this range includes everything from the most minimal possible of simply replacing the spark plugs, on out to include spark plugs and filters and a full major 60k or 90k service with all the fluids being changed and the timing belt replaced also. The following tune description is a composite description that describes tune procedures for vehicles with several generations of developments, including:
- Carbureted and fuel injected.
- Those with vacuum advance and mechanical advance and those that have electronically controlled timing.
- Ignition systems with distributors and distributorless ignition systems with ignition coils directly over the spark plugs.
- Vehicles with no onboard diagnostics built in; vehicles with first-generation onboard diagnostics that are accessed through jumper wires and blinking-light codes; and vehicles with second-generation diagnostics that are accessed through full computer hook-up.
Our composite working definition is below:
Test drive before beginning
Scan test if OBII (onboard diagnostics 2nd generation)
Scope check those that allow standard inductive hook-up to secondary ignition
Replace spark plugs
Replace air filter if dirty, and the fuel filter for carbureted models
Full voltage test of rotor (those that allow standard inductive hook-up)
Wet test cap & wires for voltage leaks. Check insulators for leakage where they pass through spark plug tubes.
Manually check high-tension connections at coil and cap for corrosion
Note whether cap, rotor & wires are factory or aftermarket
Clean top surface of coil (coil-in-cap models)
Check and adjust timing when applicable
- Does jumper connection cause timing to change?
- Verify that TPS contacts are engaging. If necessary, bypass to set timing. (Bottom two terminals on most)
Mechanical advance free?
Vacuum advancer:
- Diaphragms not ruptured?
- Able to move breaker plate?
- Gets proper vacuum signal?
Check EGR system.
- Does EGR valve get vacuum signal?
- Does EGR kill engine or cause a significant rpm drop at idle