Help with charging problem...

M Murch wrote in rec.autos.tech

How is your battery and cables? Are they tight and clean? You must recharge your battery alot if you read less than 12 volts. However, are you sure your tester is any good? Are you sure that you are reading on the proper scale? What are the symptoms of this failed alternator? If it really is failing, have you changed your voltage regulator? I personally find it hard to believe that you are actually having this many failing alternators. Either you are replacing them while they are still good, or there is something else wrong. If the alternator is overheating then it is due to a short in system, not because the cooling fins aren't blowing enough air. You need to try a known good multimeter, on the proper scale, to be sure that the alternator isn't working. Then check the belt to make sure it is tight. Check the voltage regulator, common for those to fail, and check all battery connections. Then check the rest of the car for shorts.

I have owned a lot of cars, and have only replaced a few alternators, and never more than one per car.

The voltage regulator's are built in so everytime I get another alternator, I am replacing the regulator also. Since this has happened over several years, there have been several batteries involved.

The shops that I mentioned could not explain it either. They could only suggest replacement of the parts for free. And I did that after they tested it and found alternator problems.

On many I do think it was cheap rebuilds (Autozone-Chief lifetimes). Maybe they did not replace all the key parts in the rebuild. But some had to be good parts. And some did last over a year.

A long time ago I heard about Chevy starters could do this. Something about a short that caused problems. I have only replaced the starter once in 27 years. But I had suspected heat because it is always worse after the car warms up.

What about the ground cable? Right now it attaches to the alternator bracket. I have sanded that. Cleaned the battery posts and the cables. I did notice a little crud on the post this time even though I have a clean battery and the green/red pads on the terminals.

Since the battery has two neg terminals, can I use the second (non post) to run another ground from the battery.

FYI - car runs great and has 190K. Replaced the transmission with a rebuilt in 1995 for $350. You have to like that.

Mike

M Murch wrote in rec.autos.tech

Ok, I know some are like that, but it is difficult to tell which is which.

Have you tried to rebuild it yourself? Or torn one down just to see what has failed? Sometimes you can get a good idea of what is going on by doing that yourself, or having someone who knows about electrical stuff take a look at it. Say an electrician?

Heat can and does affect components. And with the built in regulator that is simply more to be affected. But that many alternators is really pushing things. Especially since this is a problem that is probably fairly unique to your situation.

I would try to find a better mounting place for the ground, and it wouldn't hurt to connect another strap from engine to frame.

Probably, but what you should do is get a digital multimeter and read voltage between the positive and negative posts, then between the positive post and negative cable, then between the positive post and ground. Then do so between ground and the positive cable, then between ground and the positive cable at the starter. Any differences should be negligible. If there is more than a 1 or 2 tenth of a volt difference you are looking at a bad connection. I would also try a trick that someone has mentioned before. Use a test light, disconnect the negative cable and connect the testlight between the negative terminal and the cable. The light will probably glow dimly because there is probably something drawing a little power, but if it glows brightly then something is either on or shorted, causing your problems.

Good deal. Nice to hear of a car lasting so long.

Any competent local alternator shop SHOULD be able to fix the "problem" GM alternators so that they last reasonably well. Yes, GM built some real crappers, but good rebuild shops know how to make them work, or can recommend how to modify a different model to use which will fix the problem for good. Not every 77 Monte Carlo out there spent its whole life running around with a half-dead alternator.

OK -here is what I found.

Yesterday, I tested the alternator at O'Reilley auto parts and it tested good. The dash gauge was reading 11 when it was 14 volts. At some point the guage and the multitester found some crappy rebuilds. After that I guess I did not always double test with the multitester. But I am convinced that the auto parts places tested them before I bought a new part.

But right now I have a working alternator but the acid test is a long drive of 1,000 miles.

Mike

M Murch wrote in rec.autos.tech

Good luck. By the way, for your piece of mind, check the dash voltmeter, it may be reading correctly the voltage it is receiving, but have a bad connection going to it. Or it might just be bad, if so, replace it. It will do your piece of mind a whole world of good. By the way, not all multimeters are equal. When I was an electrician in an industrial plant, we all had very expensive multimeters. An elevator tech came out to work on an elevator (something we were not licensed to do). He came into the shop and told us that our 440 was really only about

200 volts and that is why the elevator wasn't working. After my mouth dropped open, I grabbed my multimeter and checked. It was a solid 440. He was using a cheap radio shack meter. He believed my meter and went on to find the real the problem.

Make sure that you have a fully charged battery before starting the engine with the new alternator. The brushes on the alternator need to wear in to the slip rings on the rotor. If you force the alternator to charge a flat battery during this "wear in" period, the gaps between the brushes and the slip rings will produce arching which in turn will burn up the brushes and degrade the surface of the slip rings.

The instruction sheet that comes with the alternator will have a warning about making sure that the battery is fully charged before starting the engine.

Don't just "sand" the end of the cable, toss it in the garbage and install a new one, do the Positive cable too while you're at it ( you did say this is a '77 car right? Oh to be 17 again ;-). Think about how much these items cost vs what you've spent so far. -PapaRick

Paparick,

I sanded the alternator bracket. The cable looks like new. I still cleaned the terminal ends with a wire brush. I change cables everytime I get a new battery (3 to 5 years).

This 77 Monte was my college graduation present to myself. Drove off from my wedding towing cans with it.

Now my son(16) wants it. Yesterday he had a cd installed. I cried when they cut the dash to make it fit. He just does not appreciate 8 tracks like I do. The only thing I get is knowing that he is driving a safe car.