Can't rotate Idler Pulley, but belt can

[ShadowClutch]

While changing my serp belt yesterday, I inspected all the pulleys for rotation and wobble. Everything spun smoothly, with ease, except for the idler pulley. I could barely get it to rotate. I marked the edge of it with a Sharpie, and put the new belt on. With the new belt on and the engine idling, it spins just fine, but the tensioner oscillates a bit wildly. Could the semi-seized idler be causing excess drag on the belt and then skipping?

I'm certain I'm going to replace the idler pulley, anyway, but I needed to test the logic of why I could barely spin it with the belt off, but the belt is able to spin it smoothly.

 

[The_Roadie]

The belt has more friction on the pulley and the power of the engine behind it. A seized pulley will burn the belt and then you lose cooling and power steering, so be quick about the replacement.

 

[ShadowClutch]

The belt has more friction on the pulley and the power of the engine behind it. A seized pulley will burn the belt and then you lose cooling and power steering, so be quick about the replacement.

Thought so. Thanks, roadie!

Is there any reason to choose the more expensive AC Delco part over the Dorman? I know, in some cases (like engine mounts), there are differences.

 

[MAY03LT]

i just want to say good job marking the pulley. i know a few "technicians" who cant grasp that concept.

 

[ShadowClutch]

i just want to say good job marking the pulley. i know a few "technicians" who cant grasp that concept.

Wow.

Thanks!

 

[floridafitz]

I purchased the Dorman tensioner assembly with pully through Amazon I think. The pully spins freely, as you would expect. It's a perfect fit and an easy install. Did all three at the same time...belt, tensioner and idler pully. All's good.

 

[ShadowClutch]

I purchased the Dorman tensioner assembly with pully through Amazon I think. The pully spins freely, as you would expect. It's a perfect fit and an easy install. Did all three at the same time...belt, tensioner and idler pully. All's good.

I went with the Dorman Idler Pulley from Amazon for $12, it should be here today. $12 isn't a significant wager, and all this thing needs to do is spin freely.

 

[jaguarjoe]

I didn't do the idler yet, but I did do the belt. I used an EPDM rubber belt. Being in service only a month or too, it's too soon to tell how wise this choice was, but it got a beating pounding I0-75 from the D to Tampa and back.

 

[floridafitz]

Depending on your miles, could be the tensioner spring is failing too in addition to the pulley. I'm high miles at 178k. Mine was bouncing around too much and was noisy at engine shut off. Maybe your problem is isolated to the pully. Either way, it's an easy fix.

 

[ShadowClutch]

I didn't do the idler yet, but I did do the belt. I used an EPDM rubber belt. Being in service only a month or too, it's too soon to tell how wise this choice was, but it got a beating pounding I0-75 from the D to Tampa and back.

I'm fairly sure the belt I just changed was the factory belt (if so, that's 142k miles); it had so many cracks it looked like a GY Gatorback, but like I said, no missing chunks or tears along the edge. I'll snap a pic of it when I get out to the garage to replace the idler pulley. I'm also not sure how long the IP has been seized, could be months, or it could have been years.

I never noticed any sounds I would have traced to the belt itself, or failure of any other accessories. Just recently, I noticed a subtle whine that sounded like an electric motor. I would describe it as half WHIR and half BZZZ that increased in pitch with increases in RPMs. This may be it, or it might be the wheel hub/bearings.

Depending on your miles, could be the tensioner spring is failing too in addition to the pulley. I'm high miles at 178k. Mine was bouncing around too much and was noisy at engine shut off. Maybe your problem is isolated to the pully. Either way, it's an easy fix.

I will see what happens after I replace the IP, if the Tensioner is still flexing too much, I'll go after that.

 

[ShadowClutch]

By the way... Ow. Changing belts/pulley is really frustrating when the engine is hot. I will say that with the new idler pulley, I'm getting a lot more feedback in my steering wheel... Guess my PS has been suffering for a while.

Interestingly, I discovered the belt on there was not the standard size, so it was not the factory belt.

Belt gore:

Also, the Dorman part that came in seems a little different from the idler pulley that was on there. Note the shiny section where the smooth side of the belt polished this seized pulley.

The size/shape difference was of some concern, as the clearances seem smaller with the Dorman part. I opted to use the reduction collar that with the Dorman part and the factory bolt.

It seems the mounting bolt sticks out, but the pulley is mounted and secure. Didn't get a pic of the pulley with the belt on, but it has clearance on both sides, and runs smooth. No wobble skipping.