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Idler Pulley Question

Dead Eye

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How far should the idler pulley stick out on the 4.0Liter engine? mine sticks out about a .5 an inch compared to all of the other ones. The reason i ask is because the belt keeps slipping off the c/s pulley. we have reason to believe that the idler is bad because the tensioner was replaced, and it is the third idler i have gone though. it could be the brand. has anyone had problems with the orielly line of idler pulleys? Im thinking of just buying a oem idler pulley.
 


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straycat

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Well..it is a 1990 Truck, Bro. It could be yours is ready to be replaced...the belt shouldn't slip off. Does it looked twisted a bit, or too loose? Any noises at times? How many miles on the pulley and has it ever been replaced before?
 

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Half an inch is way too much. You should be able to stick a straight edge across any two given pulleys and have them be flush, or very close to it.
 

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Here's what you really need to know.

The pulley is metal and has a bearing pressed "so far" into its bore.

You can replace that bearing, it's probably a 6203xx series, readily available.

Chances are that your idler pulley's bearing has walked out of that bore or was pressed in to the wrong depth. It's simple to see, but you need to remove the pulley. Take a socket that fits inside the bore and rests on the bearing outer race and tap it with a hammer lightly until it sits further/less into the bore to get it properly aligned with the rest of your serpentine system.

If yours are plastic pulleys, ditch that and get metal ones. Last one I bought was about $18.
 

Dead Eye

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ok thanks. yeah. it is sticking out 1/2 inch from the tensioner pulley, and the tensioner looks flush with the fead. but we suspect a flange is on the engine side of the fead. so im going to pick up a motorcraft pulley if i can, and if not, i will try what you said earl. the last couple of pulleys that i pulled off looked like the bearings where not flush with the pulley itself. so that sounds like a good idea.
 

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Wrong tensioner? But that doesn't matter if you can correct the idler pulley alignment yourself...(no sense in wasting more money buying the correct tensioner unless the idler pulleys keep failing)
 

Dead Eye

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and it has been less than 1000. just replaced the harmonic balancer. the tensioner has the same amount of miles. and it squeaks, squeals. that is, before the belt jumps on top of the harmonic balancer flange.... and starts to destroy itself.
 

Dead Eye

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well. i tried hammering on it for a good 30 minutes. but nothing. right after i took it out, i looked at it, and it did look like the bearing was put in funny. one side was sticking out, and the other was in.... it looked about 1/32 of an inch off.... so i think im going to purchase a oem pulley and not buy the ones from orielly anymore.... its only like 25 bucks which is 5 dollars more than the aftermarket, so its not that bad. but i will inspect it out of the box.
 

Dead Eye

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Ok. i ordered it. turns out it was like 32 dollars. but still 12 bucks more for a perfectly manufactured pulley. that is not a cheap chinese knockoff.
 

Dead Eye

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ok. so i got the new pulley, looked at it. and it looks like the old one. so the bearing is not supposed to be perfectly flush with the pulley?
 

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is the bearing offset from the center? if it is, maybe you had it installed backwards. a 1/4 inch offset will throw it a half inch out if put on backwards.

AJ
 

Dead Eye

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well. we figure now that the crankshaft is back against the engine too far. we are going to pull it out, and see what happens. we just took the idler pulley and pushed the bearing forward toward the front of the car. the squeaking and squealling has stoped for the most part. i don't know when we are going to pull the crankshaft out a .5 an inch.
 

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