Upper AC/Alt Idler pulley used as Lower AC/Alt Tensioner Pulley

So I have had an issue with the bearings on one of my pulleys. I figured I would go ahead and replace the upper idler pulley because it was the cheapest of the two. 60 for the upper and 150 for the lower. Well it turns put the upper was just fine, and its the lower tensioner pulley making all the noise.

I decided I was going to use my old upper as my new lower.

I examened the lower and noticed on the back side, it has a lip to keep the pulley pulled off the tensioner bracket. I found a washer that was the same thickness of that lip and threw it behind the old/new replacement and that solved the issue of running into the tensioner bracket. The upper pulley is a little bit larger in diameter, but the belt length isn't changing so that doesn't matter. Luckily enough on our cars, mits gave us plenty of tightening and loosening adjustment on this pulley.

I must say, if you ever need to replace the lower pulley, save yourself the money and just buy the upper and add a washer or two to match the lip that keeps the pulley off the tensioning bracket. Much cheaper solution.

Suggestion is good! Actually did this today, I have a spare DOHC so I just took my chance and replaced both, voila, horrible noise under load gone!!

I am positive the SOHC 3.0 and 3.5L Diamante's have the same pulley's I will find out later on in the week. I am going to get a few spare if they are!

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Originally Posted by TUFFTR

Suggestion is good! Actually did this today, I have a spare DOHC so I just took my chance and replaced both, voila, horrible noise under load gone!!

I am positive the SOHC 3.0 and 3.5L Diamante's have the same pulley's I will find out later on in the week. I am going to get a few spare if they are!

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What kind of noise did it make? Mine makes a "shchhk shchhk" type noise lol only when flooring it or in a high gear at low speeds.

I'm pretty sure mine made noise (a rattle while revving, and at a certain RPM). I never got around to replacing them. Great tip!

great idea, i'll have to keep that trick in mind. had to replace my lower a while back, but luckily i had a spare. i have a dohc 6g72 and 6g74 sitting out. i'll compare them later
is the lower pulley more expensive because it comes with the tensioner? or is it really 150 just for the pulley? that's way too much for a pulley.

It is the pulley and new bolts, aka tensioner bolt/lug and mounting/locking bolt. Austin@STM quoted me $130 @ 10-11-2010 for the lower for the guys that still want the correct/stock setup.

The pulley would make a terribly loud whine. I mean you could hear the pulley over the exhaust, even under boost. I have straight pipe turbo back, gutted cats, and no muffler. If you were to spin the pulley in your hand, and hear the faint (on a good one) noise of the resonance of metal itself, amplify it by 100x. It would also have the bearing locking up for fractions of a second, sounding similar to an AC clutch, but worse. It would also have belt chirp. It would change about every 15 minutes, except for the whine, that was ALWAYS there. This is the 2nd set of pulleys I have had, well now third, the first two had the identical whine, but I know it isn't from over tightening. I am very picky about my belt tension being perfect.

wonder why its so much
cherry hill mits its even 140

because mitsu can charge whatever they want for it even though all pulleys are pretty much the same, if they say its 3 times more than it is.

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Originally Posted by Austin@STM

because mitsu can charge whatever they want for it even though all pulleys are pretty much the same, if they say its 3 times more than it is.

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And this is when it takes ingenuity to save money!!! That and some common sense so you don't do something stupid or unsafe.