Geo Metro.. might be a bad alternator?? Please help

[fire-stick]

Any time anything electrical is turned on, (not the little stuff, just the big stuff like the lights, and the heater), a LOUD squeaking sound is made.

I thought, change the belt... I did... now it has a new belt and it's plenty tight, but it still squeaks.

The only think the alternator belt hooks to is the main pulley at the bottom, (crank), and the water pump.. and the water pump is brand new so I don't see it making much drag on the belt..

I just listened to it outside and it really doesn't sound like the sound is even coming from the belt (the belt isn't slipping it looks to be running the same rate as the pulley) The sound is seems to be coming from the back of the alternator. Plus whenever the alternator is engaged it kinda bogs the engine down..

So, could it be the battery, alternator, belt, belt tension, any connections? Please any input will be much appreciated.

 

[InTheDark]

Sounds like the alternator to me, maybe bad bearing? Sounds like you've ruled out everything else and have isolated the noise. A mechanics stethescope or piece of rubber tubing might help confirm your suspicions. It would make sense that the noise happens when you turn on any major electrical load because it puts more stress on the alternator. When you took the belt off, did you spin the alternator to see if it spins freely?

It wouldn't be a bad idea to check the battery as well, because even if you install a new alternator a bad battery can destroy it pretty quick.

 

[carbine15]

Such an easy swap too. get out yer leatherman and get to swappin that baby out!

 

[fire-stick]

i didn't check to see if the it spun freely... but i will do that just to check

i will also check the voltage on the battery..

what kind of voltage should i get

i know its a 12 volt battery but with it running what should i get

 

[Lynx_Arc]

under no load you should get 13-14v charging and about 12 - 13v on the battery with then engine off. probably got a dry bearing on the alternator like he said get a rubber hose and turn on the AC and headlights and listen under the hood and figure it out. It is possible though that the load is pulling on the belts causing an idler pulley to squeal too.

 

[shooter08]

When you do a charging system test you need to drain off the surface charge first. Just turn on the headlights for
30 seconds and then measure the battery voltage and take note. You then start the car and turn on most things electrical to put a load on the alternator. Then take a voltage reading it should be 1.5 volts above base voltage.
As to your noise a mechanics stethoscope would allow you to isolate each component from all the rest of the noise.

Dave S.