How I found and fixed my fan belt squeak...

I've had a really loud squeak from the front of my '92 XJ I-6. It sounded like a dry bearing although I've replaced most of these (water pump, alternator, PS pump). When the motor was cold it didn't squeak but as it warmed the squeak would come and go and when warmed up all the way, squeak continuously. I figured it was the fan bearing since it was the only one I hadn't replaced and was preparing to give the dealer $100 or so for a new bearing/bracket assy. But I thought I'd give it one last look before tossing the cash.

Listening to it come and go it sounded like it came from the (new) water pump. It is hard to tell where sounds come from of course. I figured if it was indeed a belt squeak then I might lube it momentarily with Windex. I expected to squirt windex on the belt and hear no change in the squeak if it was indeed a bearing. But if it was a belt I'd hear the squeak change somehow.

Windex made the squeak go away for a few seconds until it dried out! Knowing this there are still two sides to the belt: the notched side and the smooth side. Squeak could come from either. But since it seemed to come from the water pump and since the water pump is driven by the smooth side I guessed smooth side. I simply held a bit of wax against the belt smooth side where the belt goes over the PS pump with the motor idling. Squeak went away and has remained gone for several days now.

I suspect that the PS pump isn't quite aligned with the water pump and that the belt slides slightly sideways as it goes over the water pump pully, probably jumping and not sliding smoothly thus making the chirping sound.

Ahhh the sound of silence... and my $100 is still here to have a good time with.

mhead said:

. I simply held a bit of wax against the belt smooth side where the belt goes over the PS pump with the motor idling. Squeak went away and has remained gone for several days now.

Ahhh the sound of silence... and my $100 is still here to have a good time with.

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Sounds brilliant to me. And it should reduce abrasion on the belt. What did you use--something like Butcher's Wax?

No, just some surf wax. I'm near the beach here in SoCal so there's plenty of it.

Someone suggested I should use some thread anti-sieze. This is a slivery goo that has silver or some other metal particles ground up within it. Don't know if it is better than wax.

I'd guess my surf wax is a lot like a simple candle wax. You could probably just use a bit of candle wax.

Right now I'm wondering how long it will go until I have to re-apply.

Belt must be squealing for a reason, is the belt tensioned properly. Masking the sound never fixes the problem.

I've used a simple crayon for tracking down belt squeals (Crayola Titian Red works best ). Just hold it against the pulley for a second while the engine is running, and you can effectively eliminate that pulley as the source.

I'm having the same problem with my 87 MJ 4.0 and I've replaced the water pump, power steering pump and both Idler pullys and the problem is still there, and I used a belt tention gauge so I know that's not it. I also used a strait edge to allign the pullys and that didn't get it. I did notice that at least one of the smooth pullys is now contaminated with clumps of a rubber like compound so my next effort will be to decon the pullys and install the new belt. I'll try that first and if that wont get it I'll try the sex wax thing, whatever works.