Starter problems

[Marr-TA]

Hey everyone, I tried to start my car this morning and she started to turn over but then stopped turning the flywheel. I kept trying but all I heard was the starter motor turning like it wasnt engaging the flywheel or something. I plan on putting her up on stands this afternoon after work and pulling the starter out but I wanted to see if anyone had suggestions on what part on the starter it might be so and what to look for and where, if not on the starter, the parts might be located. Thanks, Marty

[Philo]

If you hear a whirring sound when the key is turned to start, but the engine does not turn, the problem is probably the starter 'bendix'. It is located on the starter, and consists of a sprial gear with another gear mounted on the sprial, and a spring. I am fairly sure this is the method of operation (but I am not an expert on the operation) When the starter is used by turning the key, it needs to engage the flywheel to crank the engine. But after the engine starts, it needs to release the flywheel or the flywheel will begin to run the starter and will simply tear it apart from high rpm. (The crankshaft is geared along the outer edge and is quite large compared to the gear on the starter). So, when you hit the key, the starter gear moves along the sprial gear and engages the flywheel (from centrifugal force). Once the engine starts and you release the key, the spring returns the starter gear to it's resting position so the flywheel is not in contact with the starter. It sounds like you could have a broken spring or gear on the starter. Depending on the make of car, the bendix is generally available as a component for the starter. You may want to check the price difference between a bendix and the entire starter, and how much work it would be for you to replace the bendix. Also, if you plan on keeping the car for a while, you may decide that the bendix failure is only the first shoe to drop on a starter going bad. Good luck.

[Marr-TA]

Thanks Philo, I pulled my starter off last night and the gears and the spring looked good so I went to the part store and had them test it. The gear popped out like it should and it spun up like it should. Now I know it wasnt under load but here is some more info on the problem. It does start to turn over and then it just sounds like the motor is turning but not engaging the flywheel. Is there some sort of clutch in the starter that could be slipping? I just hate buying a 150.00 part if that is not the cause of the problem. I know I have some performance problems with the car and I believe its the CAT. Could a blocked CAT cause so much back pressure that it makes the starter not powerfull enough to start the car?

[Philo]

Originally Posted by Marr-TA

Thanks Philo, I pulled my starter off last night and the gears and the spring looked good so I went to the part store and had them test it. The gear popped out like it should and it spun up like it should. Now I know it wasnt under load but here is some more info on the problem. It does start to turn over and then it just sounds like the motor is turning but not engaging the flywheel. Is there some sort of clutch in the starter that could be slipping? I just hate buying a 150.00 part if that is not the cause of the problem. I know I have some performance problems with the car and I believe its the CAT. Could a blocked CAT cause so much back pressure that it makes the starter not powerfull enough to start the car?

First I would get someone to turn the key for you, and you look at the engine - for example the 'fan' belt. Then you can see exactly what is going on. If the belt is not turning then the starter gear is not engaged. The load on the starter gear is only applied after it spins out to the end of it's sprial gear. If it starts to turn the engine but then stops, but the starter continues to turn, there is a problem at the end of the sprial gear or the gear its self, that is letting it release the gear from the flywheel gear. (Or it could be a problem in the starter that is making it hesitate long enough to make the spring think you have released the key - and it begins to push the starter gear back). I have never heard of a clutch in an automobile starter - they are just an electric motor on a shaft. It is possible that the gear and sprial gear are available as parts - they were in older autos. Also, I can't imagine enough back pressure (on a car that runs) in the exhaust system to cause an engine to not turn over with the starter. It would have to be completely blocked and no leakage anywhere, and even then I think the starter would work - it would just build up pressure in the exhaust. Remember, on a normal start, you are only running the starter for about 1/2 second or so.

[Marr-TA]

Thanks Philo, I feel enlightened on the inner workings of a starter now. I had someone turn the key for me last night and it does just what you said, it starts to turn the motor as evidenced by the turning fan belts and then 2 or 3 seconds later the belts stop and the starter motor continues to turn so it is being disengaged. And since I'm getting so good and throwing her up on stands and pulling the starter out (which was ther perfect oppurtunity to change that spark plug I could never get to) I will pull it again tonight and just replace it with a new one. The car has 130,000 miles on it so a new starter will be money well spent. I will also cycle the flywheel again to make sure there is no damage to it. Thanks for all your help and I'm sure others will benefit from this post.

[sixt8bird]

It sounds like the bendix gear is giving up the ghost. You can just replace the bendix or the whole starter.