Alternator

dannmarr · #1 12-01-2005, 10:14 PM

I was driving my car and everything started to dimm until it stoped running. I had it towed to the garage and the mechanic said the alternator was bad. I had the alternator rebuilt and installed it. After a week of driving it happened again. I brought the alternator back to were it was rebuilt. They claim that it's good and it charges. I checked the plug to the alternator with a volt metter and it's o.k. When I checked the battery with the volt meter the reading was going down as if the alternator wasn't charging at full capacity. I also installed the wire upgrade as instructed in the "how to". A friend mechanic said it is definatley the diodes in the alternator. Any ideas? what should I do? Have it rebuilt again or buy one from subaru? Is there something else I should check?

Earthworm · #2 12-02-2005, 11:55 AM

Ensure solid connections everywhere.

Ask them what they used to rebuild the alternator. 2 parts need to be replaced. Beav posted a how-to for rebuilding the alternator for cheap. A search will find it.

dannmarr · #3 12-02-2005, 09:37 PM

I had the alternator bench checked by Pep boys. It works fine, so what else could stop the battery from charging? Could the internal voltage regulator on the alternator prevent it from charging if the battery has a low output? (if the battery has a bad cell?) I say this because when the car stoped, the alternator was cold. As I mentioned earlier, the plug to the alternator has voltage and voltage is going to the battery. I don't know if the voltage drops while I drive and maybe triggering the voltage regulator. Any ideas?
I also need to mention that the dash lights go on and slowly fade.

UberRoo · #4 12-03-2005, 01:51 AM

In addition to not accepting a charge, a bad battery can kill an alternator. I would suspect the battery. Have it tested. Also, a loose belt can cause problems too. The obvious can be easy to overlook.

dannmarr · #5 12-03-2005, 06:41 PM

The battery is good and the alternator is good. But then again, they were bench checked and not checked on the car. Does this make a difference?

dannmarr · #6 12-04-2005, 03:55 PM

The alternator keeps the constant charge at idle, but when something is on (lights,etc) the voltage drops and the alternator does not replemish the lost voltage . I tried other cars and the alternator keeps the voltage at a steady high voltage even after the initial drop. As I mentioned before, the alternator passed the bench test. What gives?

oab_au · #7 12-04-2005, 08:19 PM

Quote:

Originally Posted by dannmarr

The alternator keeps the constant charge at idle, but when something is on (lights,etc) the voltage drops and the alternator does not replemish the lost voltage . I tried other cars and the alternator keeps the voltage at a steady high voltage even after the initial drop. As I mentioned before, the alternator passed the bench test. What gives?

There is a small wire that plugs in to the alt on the steering pump side, of the alt, that tells the alt what the battery voltage is, if this has a bad connection, the alt will think the battery is fully charged.

Harvey.

dannmarr · #8 12-05-2005, 07:22 PM

My mechanic found out that the alt will start charging only when the RPM hits 5000! After that all is o.k. He really doesn't know if it's the regulator in the alt or the small wire with the plug end going to the alt. Anyone have any ideas?

Earthworm · #9 12-05-2005, 07:28 PM

5000RPM for the engine or alternator?

dannmarr · #10 12-05-2005, 09:31 PM

In other words; I need to rev the engine to 5000 RPM to engage the alternator.

dannmarr · #11 12-06-2005, 09:13 PM

Finally the problem has been solved! The alt had a bad voltage regulator. The guy who rebuilt the alt will replace it for free. My battery also got fried because of this problem, but I got a free replacement. The one thing the guy at the alt shop didn't like, when he looked under my hood, was the alt wire mod. He said it was overkill and advised not to add additional wires. He didn't elaborate on this. Thanks for all your inputs, especially Harvey!

dannmarr · #12 12-07-2005, 08:14 PM

If anyone needs an alternator rebuilt and you live near Lodi, New Jersey, I highly recommend RAYELCO generator and alternator shop. They went out of their way to help me solve my problem.

SVXRide · #13 12-07-2005, 08:47 PM

Glad things worked out for you! Another thing for folks to check when they run into "alternator problems" is the entire wiring bundle that feeds into the alternator. With time, the bundle sees enough heat and vibration that its insulation can become brittle and result in small internal shorts that can "eat" alternators.
-Bill (bowing in the direction of Cumberland, MD in recognition of SVXFiles who came up with this observation...)

SvX001 · #14 12-07-2005, 08:51 PM

desperate for a alternator , mines about to poop out, if you have any links so that i can purchase one that would be great