New Idler Pulley Squeal

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Apr 12, 2018 | 04:36 PM

Thinlizzy13

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Tuned

Joined: Jun 2011

Posts: 355

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From: CNY

New Idler Pulley Squeal

My 87 F150 w/300 (A/C, smog pump, power steering) is having a bad belt squeal issue. I recently did some power steering work, bled the system, and put a new Motorcraft idler pulley and Motorcraft belt on (within last 2k miles). By process of elimination (the 'ol WD-40 spray and see what stops squealing) I've determined the new idler pulley is the culprit. I spray it and the engine runs nice and quiet.
Is the pulley something I can grease? Maybe I got a defective one or maybe the "new" ones aren't quite right? Anyone out there run into this issue and have some guidance? I'm about ready to put the original on, it sqeaked a little but not nearly as bad...

Apr 13, 2018 | 08:24 AM

Inside Man

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Joined: Jan 2012

Posts: 472

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From: Somewhere in the universe

Couple possibilities here.

Got a bad pulley.

Tensioner isn't putting enough pressure on the belt.

Some kind of contaminant on the new belt and or pulley causing it to squeal.

Ive learned over the years after installing any pulley to spray brake cleaner on a rag and give the belt surface of the pulley a good wipe down before installing the belt. However now days it wouldn't surprise me if you were unlucky enough to get a bad part.

Good luck, keep us posted

Apr 13, 2018 | 12:24 PM

Thinlizzy13

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Tuned

Joined: Jun 2011

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From: CNY

Thanks inside man. I ended up putting the old belt on and it ran quiet again. Looks like maybe the WD-40 or ATF messed up the new belt...

Apr 13, 2018 | 12:30 PM

Da_Lariat_Chariot

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Joined: Feb 2015

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Belts can get contaminated very easily. Dirt, coolant, oil, ATF, you name it. I've even able to save a belt or two if they didn't get soaked using some brake clean but usually it's too late by the time they get noisy.

Apr 13, 2018 | 12:53 PM

rla2005

Fleet Owner

Joined: Oct 2005

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From: Kentucky

Quote:

Originally Posted by Thinlizzy13

WD-40 or ATF messed up the new belt...

Chemicals and belts do not mix. Expensive lesson.

Apr 13, 2018 | 04:29 PM

TobyB

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Joined: Oct 2014

Posts: 946

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From: Carnation, Wah

The other thing on the 4.9- make sure the belt's not running against the flange on
the idler pulley. The idler arm wears, and then it doesn't align correctly.
That squeaks like crazy. Mine did it from when I got it- I changed the
idler pulley, and it started up again within a week. Changed the whole assembly,
as it was worn and not tracking right, and that cured it. I now have a spare idler pulley...

t

May 24, 2018 | 07:46 AM

Thinlizzy13

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Tuned

Joined: Jun 2011

Posts: 355

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From: CNY

So I thought the belt had fixed the issue, but it started again shortly after. Finally figured out it was the alternator. Put a new set of alternator bearings in and haven’t had any more issues...