2000 Chevy S-10 starter failing nearly every 30-60 days

Hi Joe. Welcome to the forum. First you have to determine what is failing with the starter. GMs have had more than their share of teeth ground off of the flywheel but that can happen to any car or truck. It is fairly common for an engine to stop in the same position each time it is turned off, so the gear on the starter slides into mesh starting with the same flywheel teeth over and over. That can lead to accelerated wear in one spot. Often that is not much of a problem until the old high-mileage starter begins to develop rust buildup on the shaft that the starter drive slides on. The motor normally doesn't start to spin until the drive gear is engaged, but if the shaft is rusty, the gear might not be fully engaged when it starts to spin. That partial engagement can lead to chipped teeth.

The fellow who mentioned the crankshaft position sensor is not incorrect but I suspect his past experience is not related to your problem. If that sensor is not adjusted properly, (depending on the engine and brand of vehicle), or if the magnetic core is cracked, it will develop extra pulses in addition to the ones it is supposed to. While the engine is running, those extra pulses come at a time when the Engine Computer knows it should ignore them, but at the much slower cranking speed, those pulses can tell the computer to fire a spark plug at the wrong time. If a plug fires when the piston is on its way up on the compression stroke, it will try to force the engine to go backwards. That can be real hard on the starter drive gear. On some engines, a defective crankshaft position sensor will also cause backfiring or popping through the intake system. That can be a hard one to find since the engine will still run.

If you can see that the starter drive gear is damaged or won't lock up in one direction, suspect a sensor problem. If the starter just screeches, try turning the engine a little bit by hand in the direction of normal rotation, then try starting it. That will move it past the area of worn teeth on the ring gear. Usually only part of the teeth are gone so that area only affects the starter when the initial engagement takes place on that spot.

Caradiodoc

YOU brought up the crank sensor, not me. Apparently you missed these comments in my reply:

"The fellow who mentioned the crankshaft position sensor is not incorrect but I suspect his past experience is NOT related to your problem."

"If that sensor is not adjusted properly, (DEPENDING ON THE ENGINE AND BRAND OF VEHICLE), or if the magnetic core is cracked, it will develop extra pulses in addition to the ones it is supposed to"...

These threads will be read by many people searching for the answer to similar problems so we include a lot of information that might be relevant to as many of them as possible. Many crank sensors are adjustable. We would be lax in our duties if we didn't mention that. Doing so IS going to prevent at least one person from destroying their new sensor.

About 95 percent of the questions asked here are from do-it-yourselfers who often don't understand how to ask the questions properly or how to provide clues and make observations that can help narrow down the cause of a problem. It is wonderful to work with professionals such as yourself, but if you choose to keep that secret in your original post, we have to assume we are having a conversation with someone with very little experience.

One question though. Here's a quote from your first post: "After the last time the mechanic said that the flywheel was chipped at which time I took the vehicle to another mechanic who said that he had a similar problem with his 1997 S-10 and the problem with the starter was corrected by changing the crank sensor." If you're a certified tech, why are you going to other mechanics? And if the last one solved his problem by replacing the crank sensor, why are you ridiculing me for explaining what could happen?

I can't argue with anything you said except a thousand starter drives seems a little extreme. My point was / is, you might have run into failed starter drives before, but this time you are having MULTIPLE failures on the same vehicle. That adds a whole new dimension to the problem. You didn't say what was failing on these starters. If it's a problem with something the rebuilder is doing incorrectly, there are only a limited number of things that might apply. If the repeat failures are caused by something on the vehicle, you should be looking for something out-of-the-ordinary. That's where diagnosing the type of failure becomes important, but you chose to not share that either. The most likely thing to cause a repeat failure on the vehicle is the starter drive, and one failure can be dismissed, two are interesting, four suggests something stressing the drive. The weakest part of the drive is the roller bearings and the groves they roll in. If you get an extra pulse from the crank sensor that causes a spark plug to fire too soon, it will bang that piston backwards momentarily and could crack the outer roller housing. That would allow the drive gear to spin freely both ways when it should lock up one way. This is not a common failure but neither is four defective starters in a row. Would you agree we are looking for something uncommon?

If you would care to include the necessary information as to what is failing with these starters perhaps we can come up with a better answer, but until then, we work with what we're given.

Caradiodoc

Adjustable crankshaft position sensors will have a slotted mounting hole that allows it to be pushed in so far it can hit the flywheel / flex plate. That is typical on older Chrysler products where the sensor is in the bell housing of the transmission. Oem sensors come with a thick paper spacer stuck to the end to set the gap. That spacer slides off when the engine is started and is done doing its thing. You must visit the dealer for another spacer if you want to remove and reinstall that sensor.

Aftermarket sensors usually have a thin plastic rib molded into the end to set the gap. That rib wears away when the engine is running. To remove and reinstall that type, you are supposed to cut the remaining part of the rib off, then use the paper spacer.

While I am definitely not a transmission expert, I did replace about a dozen of them on Chrysler minivans while working at the dealership. At first I was cutting those spacers into quarters so I could save some for later. That way one spacer took care of four vehicles. Later I got cocky and stopped using them. I just shoved the sensor in all the way, then pulled it out about 1/16". I never had one break, but I did hear that two weeks after I did that on one van, the engine began stalling intermittently when warm. The Engine Computer memorized the diagnostic fault code for that sensor so someone else replaced it. They apparently never associated it with the recent transmission replacement. I suppose it's possible the sensor really did fail, but more than likely it was my fault for not following procedure.

The GMs I'm familiar with have their crankshaft position sensors down by the vibration damper and are not adjustable. As we speak, I have one of those dampers laying in my front yard that got destroyed by a former student. He was a very nice kid but a walking disaster. Somehow he managed to bend either the sensor or the tabs on the damper because both got shredded.

While spacing is not a concern on those, a cracked core is a possibility. In effect that makes two magnets side-by-side instead of one, and that moves the center of one of those magnets to a slightly advanced position. The typical symptom is back firing through the intake but that could also stress a starter. That is not real common but neither is four bad starters in a row. GM has had similar problems with magnetic pickup sensors in distributors too.

I don't remember hearing of cracked cores on Fords, or Chryslers either for that matter, but that doesn't mean that couldn't happen. What is much more common is the sensors failing when they get warm. With the two-wire magnetic coils, the wire breaks creating an open circuit, often when the engine is warm or after a hot soak, when the engine has been sitting for 10 - 30 minutes. With the three-wire sensors, a magnetically-controlled transistor is turned on and off rather than a pulse being developed in the magnetic coil-type. That transistor and its associated circuitry do not like heat so they are more prone to failure.

As a final thought on the subject, the air gap on the old Chrysler pickups in the distributors of '70s era cars was very critical. It was supposed to be.018". On one of my cars, I couldn't get the rotor off to replace it so I cracked it with a hammer and screwdriver. That bumped the pickup enough that it created a no-start condition. Found out the gap had increased to around.024". The thickness of two sheets of paper was enough to cause trouble.

Getting back to your vehicle, have you determined what is failing on these starters? If it is the drive gear and over-running clutch, I doubt there are that many that were defective in manufacture so I'd be looking for a cause involving the engine / ring gear. If the problem is electrical in nature, you might look closer at something the rebuilder is overlooking. Often the people doing the work are simply following instructions and don't understand what other things to look for.

Caradiodoc

Read my last paragraph. We aren't there and can't see your starter. All we have to go on is the information you provide.

Caradiodoc