charging problem...

[jamie]

hmm..

when i take my car's RPM's up under load to about 2500 and above, my voltage meter goes down into the yellow. from 14 volts to whatever the middle of the yellow is. the higher the RPM, the lower the voltage goes. so 2500 would be at like the beginning of yellow, and 5k would be neard the middle of yellow, maybe lower. when in neutral, or park. its like 3500 for it to start dropping. i'm not quite sure what the problem is, but i think i isolated it to the belt possibly slipping.
i just took the car in not to long ago for overheating(was the thermostat). but they took my belt off to manually turn my water pump to make sure that it was working. i'm thinking that they might of not tightened up the alternator pully all the way, or whatever you need to tighten. i had my mom rev the car up and i watched the belt spin around, but i'm not totally sure what slipping would look like.
if it is slipping, how would i tighten that up? i don't really feel like going to my shop about this if it is just slipping. but they would tighten it for free for me anyway.

does anyone else have any other opinions. has this happened to anyone else?

also, how much voltage would the battery put out? isn't it odd that the voltage would drop so low?

well any opinions/help is welcomed. thanks.

[rockotman]

There is no method of tightening the belt.

There is a spring-loaded tensioner pully that keeps the belt at the proper tightness. To remove the belt, you use a 3/8" drive breaker bar (or something similar) to move the tensioner in the direction that relaxes pressure on the belt, then slip the belt off of the alternator pulley.

The proper way to check the system for charging is to do a laod test on the alternator, but without the proper tools, it is kind of hard to do at home. One way that you can get a good idea as to whether or not the alternator is charging properly is to use a voltmeter at the battery.

With the car turned off, connect the meter to the battery - you should see at least 12.6 volts - probably higher for a properly charged battery.

Next, start the engine. With the engine at idle, the voltage should be higher than it was when it was shut off. This is a good indication of a properly functioning alternator.

Next, rev the engine to see what the voltage does (when checked at the battery with a voltmeter). Again, it should stay above the value it was at when not running. If it dips, then there is a possiblity that the alternator is bad, but first you should verify that it is not the belt.

Check the belt for visible signs of cracks or wear. Replacing the belt is cheap and easy (about $16 parts and will take you all of 5 minutes). Pay attention to how it is routed, and put the new one on the same way that you took the old one off. There should also be a small diagram located somewhere on the cowl above the radiator that shows the routing of the belt.

If the voltage doesn't dip (when checked at the battery with a voltmeter) when you rev the engine, then you may just have a bad connection in your dash that is causing the meter to act goofy.

If the belt doesn't cure the problem, then I would yank the alternator for testing at Autozone, or take the car to someone who has the proper tools to check the output of the alternator.

BTW, the alternator on the 96 3.8 is real easy to replace yourself, if it comes down to that.

[ August 07, 2002: Message edited by: rockotman ]</p>

[jamie]

well i broke down and took it to a shop. my mechanic said that my tensionor pully has gone bad, and so has my idle pully. he could move the belt on the idle pull, and the tensioner pully wasn't snapping back like it should.

any suggestions?

[rockotman]

Uhhh - replace them.

[jamie]

obviously. i meant as in "does anyone have any other thoughts on the matter?"