Electronic Circuits and Projects Forum

Most is already mentioned, clean and tight connections of all starter cables etc.

It sounds that what rjvj sais is very likely.

First fault:
Most starter motors have 4 brushes. 2 sets of 2 in parrallel. When the brushes are worn out the brush spring banks itself against the stop and the brush is unable to make proper contact with the commutator.

The high start current will have a higher resistance path.
The starter will still run but a lot slower on the single set of brushes.
Tapping may give you a good start but the problem will reoccur very soon.

Also check for voltage drop across your accu. Total drop at accu terminals should not go below about 9 volts during starting.

Second fault:
A starter is a dc motor and should not hum like an ac motor. It probably makes more like a whirring sound. That could be the armature running free because of a sticky solenoid which can not pre engage the starter pinion into the ring gear properly.

You need to take the starter out and clean it up, replace brushes etc. or get a reconditioned one.

Take an old screwdriver and short the starter solenoid/drive terminals to turn over the motor. Expect some sparks, but the trick works. This will eliminate any starter issues and lead you elswehere for troubleshooting.

Originally Posted by HiTech

Take an old screwdriver and short the starter solenoid/drive terminals to turn over the motor. Expect some sparks, but the trick works. This will eliminate any starter issues and lead you elswehere for troubleshooting.

Can you do that on anything remotely modern?.

We used to do it as kids on old 1950's and 1960's cars in the fields.

Your hardest part is to get easy access to the starter motor on newer cars.
Almost impossible from under the hood.

Same trick we used to do on diesel farm tractors, scewdriver didn't like that much and sometimes glowed red hot.

The old straight 4 and 6 engines were great to work on to bypass the solenoid with a few good sparks.

I'd use an old Craftsman screwdriver on a couple of starter motor contacts as well as for holding metal in place while welding. Later, I took it to Sears to exchange it for a new one. The Sears sales rep started to scold me on misuse of the tool. It was barely recognizable as a screwdriver! I told him before a few waiting customers that "if Sears has a problem with the condition or misuse of returned handtools, then they shouldn't offer an unconditional lifetime warranty. In the meantime your job is to simply exchange this defective tool for a new one without question or lecture. Besides, the high price of Sears handtools includes some mark-up for the percentage of tools that do get exchanged." I got nods of approval from the customers! LOL

Looks like I won't know until the dealership gets a hold of it. Didn't have time to mess with it before I came back to school. Thanks for all the replies; I'm sure that at least one of them would've worked.