Alternator belt problem...

[RaiderGrad78]

Hey guys,

Can any of you give me some ideas on what to check here?

1995 Ford 302 (50FAPHUE)

-Alternator belt works fine at idle.
-Anything over 1000 rpm and there is a loud squeeking noise (doesn't sound like belt slippage but it could be I suppose) and the belt starts burning up, leaving black residue everywhere and smelling up the whole place.
-After this happens the alternator pulley is very hot to the touch. I guess it could be from the belt but could it be a bearing inside the alternator?
-Alternator pulley spins very smooth and freely, not any play it it if I try to wiggle it.
-Belt becomes blurry when the rpms are increased, almost like it has a little side-to-side vibration at a very fast rate.
-Bought a new belt and this is still happening.
-Alternator is about 4 years old but boat has been sitting for two years.
-Everything looks (to the eye) like it is aligned well.
-I tightened the belt as good as I could get it by hand, didn't help.

Uh, help?

 

[RaiderGrad78]

Re: Alternator belt problem...

I did want to note that the pulley does seem to be a little rusty. Not horrible, but not perfectly smooth either.

 

[Don S]

Re: Alternator belt problem...

Start it up and look and see what isn't turning. That will probably be your problem.

 

[RaiderGrad78]

Re: Alternator belt problem...

Everything seems to be turning without any trouble.

 

[Lyle29464]

Re: Alternator belt problem...

How many belts do you have on the engine? What do they run?

 

[RaiderGrad78]

Re: Alternator belt problem...

Three belts. They run the power steering pump, impeller, and alternator. Thanks for the responses guys, I know it's not easy to diagnose problems on a forum.

 

[Don S]

Re: Alternator belt problem...

If the belt is loose, the alternator at rpm is putting more load on the belt than anything else, therefor that is what is probably screaming, it also has the smallest pulley.
Clean the rust off the pulleys and paint them with some rustolem paint and let dry for a couple of days. put on a new belt and tighten to specs.
The rust rubs the belt just like sandpaper, that's why the belt is loose, it's a little narrower.

 

[RogersJetboat454]

Re: Alternator belt problem...

When you install a new belt, how much of the slot on the alternator bracket do you need to use in order to tension the belt? If you need to move the alternator all the way over to the end of the slot, you may not be adding enough tension, and need a smaller belt. A shaking (blurry) belt would say to me that you may not be tightening the belt as much as it should be.

Whats your static battery voltage with out the engine running? What is the voltage when the engine is idling, and what is the voltage when the belt starts slipping (if you know)?

Have you checked the alignment of your pulleys? You may be able to eyeball the alignment, or put a strait edge on the pulleys to see if they are off.

I would also clean as much of the rust off the pulleys as you can. A little surface rust will be cleaned off by the belt and is fine. If you have big chunka's of flaky rust, they need to be removed, or the pulley needs to be replaced.

 

[fishrdan]

Re: Alternator belt problem...

I tightened the belt as good as I could get it by hand, didn't help.

Explain further...

You need to use a pry bar on the alternator, to set the belt tension,

 

[RaiderGrad78]

Re: Alternator belt problem...

Explain further...

You need to use a pry bar on the alternator, to set the belt tension,

Well I was on the lake and didn't have a pry bar so I loosened the bolt on the bracket and pulled the alternator as tight as I could while re-tightening. After reading the responses I suspect that my belt may still be too loose. There is still a little play in it so I will try to tighten it again using a pry bar. I'll also take a wire brush and clean and repaint the pulley while I'm at it.

Thanks again guys!

 

[benjh1028]

Re: Alternator belt problem...

Same exact engine, same exact problem. I tried tracking the problem down over two seasons. I tried everything - different belt, balanced pulleys, coated pulleys - nothing worked. Spent lots of $ with a mechanic with no results. Finally,even though the alternator tested "good", I replaced it and the starter. Haven't had a problem since.

Ben