Squeaky Alternator at Startup - Loose Belt?

[kjarrett]

...that's what I'm guessing, since I just installed this alternator a couple of months ago:

Cold: http://bit.ly/gEexXh

A mile or so later: http://bit.ly/gFuB5s

I know how to tighten the belt, but how do I know it's tightened the right amount?

TIA,

-kj-

[Mike Gerber]

"how do I know it's tightened the right amount?"

You should have about a 1/2 inch deflection at the center of the belt's longest span.

That doesn't sound like a belt that's slipping to me. That noise may be coming from the alternator itself. You may have tightened the belt too much and caused the bearings in the alternator to fail, or the alternator may just be defective. Try removing the alternator belt and starting the car for a minute to see if the noise goes away. It could also be a water pump that's on it's way out. You can remove each of the 2 accessory belts to determine which accessory is making the noise. You can also try listening with a mechanic's stethoscope or a piece of garden hose. Start the car and then place one end of the garden hose in your ear and move the other end around to all the accessories. In either case, if it is the alternator it should be under warranty.

Mike

[Zembonez]

Take a spray bottle filled with plain water and spray the belt when it is making the noise (obviously keep clear of the belt). If the noise goes away, it's the belt.

[kjarrett]

Originally Posted by Zembonez

Take a spray bottle filled with plain water and spray the belt when it is making the noise (obviously keep clear of the belt). If the noise goes away, it's the belt.

Awesome. Thanks. I'll try this first thing tomorrow and post the results!

-kj-

[Zembonez]

Steer clear of moving parts and try to spray the water on the inside of the belt where possible. It's not a fix, but it will temporarily quieten a squeaky belt. If it doesn't at least change the pitch of the noise substantially, the problem is likely something other than the belt.

[Mister_Perkins]

I would check to make sure that its sending back the proper amount of voltage to the battery.

[dave1811]

I am with Mister Perkins on that, what is the voltage output? If you don't have a volt meter, you can normally get a digital one for around $20-$25 at Autozone, O'Reilly's, Walmart, etc. I would think the voltage output should be in the neighborhood of 13.5-14.5, somewhere in there. That's what my cars normally are. Sounds like a bearing noise to me though but definitely check the belts first. If you take the belt off the alternator you should be able to determine if it is the belt, alternator bearing or one of the pulleys that is driving the Alternator.

Good luck and let us know the results!

[kjarrett]

Ok. Autozone's tester reports it's putting out 14.72v (no load) and 14.66v (loaded).

Squirting water on the inside of the belt SEEMED to help a LITTLE but it quickl dissipated and started wailing again.

The AZ tech said they'll replace it if I pull it and it screams for them on the bench. Not really into going through all that work to probably discover it's fine.

He said it might be the idler pully. Any way to check? Sure don't feel like sticking a hose or any other kind of listening device down there with the engine running.

What I don't understand is why the engine heating up eliminates the noise. Someone school me, please.

TIA!

-kj-

[Mister_Perkins]

Stuff expands when it gets hot, so the pulley bearing may be expanding and going slightly off angle making it have a squeaking noise. That's my guess

[kjarrett]

Originally Posted by Mister_Perkins

Stuff expands when it gets hot, so the pulley bearing may be expanding and going slightly off angle making it have a squeaking noise. That's my guess

I hear you but that seems to be the reverse of what's happening. It squeaks when it is cold, quiets down when it warms up.

[kjarrett]

What about the power steering pump?

[dave1811]

You can eliminate the Power steering possibility by taking off the PS belt and see if that eliminates the noise. Just need to loosen two bolts on the PS unit to check at least that issue and eliminate that as the culprit or not.