2004 Mustang Cobra Serpentine Belt Squeaks - Ford Mustang Forum

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post #1 of 9 (permalink) Old 03-02-2008 Thread Starter
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2004 Mustang Cobra Serpentine Belt Squeaks

My 2004 Cobra just turned 50,000. I had a performance tune at 36,000 - crank pulley replaced, idler, Predator tune with dyno. 425 hp at the wheels. Love it!

The serpentine belt started squeaking a couple months after tune. The shop replaced an idler and the belt, but the squeak came back. Tried one more belt, same result. Haven't tried any soap or sprays - shouldn't need that, right? That's where I'm at now. Sounds like loud crickets!

Any suggestions?

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post #2 of 9 (permalink) Old 03-02-2008
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You might want to look at this, it increases the belt wrap around the supercharger snout.

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post #3 of 9 (permalink) Old 03-02-2008
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Have you checked your alternator or wpump bearings? Those might be out. Mine used to squeak a lot before.
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post #4 of 9 (permalink) Old 03-18-2008
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Just a slight misalignment of the pulleys is enough to make a ribbed serpentine belt make noise. Also a belt that has been slipping due to a faulty/weak tensioner will cause the rubber on the belt to harden and form a "glaze" on its surface. Even after installing a new tensioner once it's glazed it will want to slightly slip and make noise.

Check the pulley alignment and tension. Check also to see if anything is leaking onto the belt's surface and that there isn't any crud built up into the belt's grooves.
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post #5 of 9 (permalink) Old 04-01-2008
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Also, do not use anything other than a Gates belt! I have had 2 cobras and both made noise with the Goodyear belt. Also, go with the tighest you can possibly fit. I put a new belt on after pulley swaps, as well as many of our mustang group, and all have had the same chirping issue like you. Once we figured out the tighest possible Gates belt we could manhandle on, we have all gotten rid of the noise. So far so good. So if your pulley combo calls for a certain size belt, try to go with something at least a 1/2 inch smaller. But be ready to fight it on! You can also notch your tensioner in order to get more room to fight it, but all worth it in the end.
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post #6 of 9 (permalink) Old 07-04-2008 Thread Starter
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Originally Posted by The Greek View Post
Just a slight misalignment of the pulleys is enough to make a ribbed serpentine belt make noise.
Right on Greek! My mechanic puzzled over this and finally found that the Metco crank pulley was a hair forward out of alignment. We sent it out for a little milling (I think .003") and no squeak!!

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post #7 of 9 (permalink) Old 07-06-2008
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I might have to try a new belt. When I bought the car a few weeks ago, it didn't make any noise and all of a sudden I got the crickets. LOL

After paying attention and realizing mine wasn't doing it at idle, but only after you hit the gas, then I realized it was probably a belt. I did try "Belt Conditioner" from CMC, but when I sprayed it on, it seemed to make the belt squeak more at idle. LOL

After that maybe it helped lessin' it a bit, but it's come back. So, I might have to try a new belt. It just drives me nuts to hear my car squeaking like that when you drive by a bunch of other cool cars. LOL

Thanks for the tips here.

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post #8 of 9 (permalink) Old 08-02-2008 Thread Starter
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Metco 2 Piece Crank Pulley Misaligned 0.030"!

After milling 30 mils from the Metco crank pulley, the belt squeaking stopped permanently, didn't even need a new belt.

By the way, I tried some Gates spray on belt conditioner. It made the squeaking much louder, more like screaming. Bad idea!!
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post #9 of 9 (permalink) Old 08-03-2008
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belt squeel

Like BlkJak said. Do stay away from the belt sprays and soaps. Look your belt over very carefully and check your pulleys with a straight edge against one another. Check to make sure all pullies are good and snug. Odds are it will be your belt. Go with a smaller gates belt. Just a tad smaller than what you are running now. Good luck.

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