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New belt tensioner pulley too big?


A while ago I replaced the drive belt, tensioner and idler pulley on my 02 Saturn SL2.

One thing that worried me was that the pulley on the new tensioner is way bigger in diameter and thickness (the area where the belt rests) in comparison to the pulley on the old tensioner. Both tensioners look different too, but the mounting holes are the same.

This is the ACDelco tensioner the store carries but it costs way too much for me, it looks identical to the one I had in the car. I am not sure if it was ever replaced though:


This is the new tensioner I installed:


Because of the differences in the tensioners, I popped the hood to check on the drive belt and tensioner with the engine running. There are no funny noises, but I can see the belt moving side to side in the tensioner pulley.

While checking the belt, I noticed the crankshaft pulley was wobbling. Is this caused by the new tensioner? Maybe the crankshaft pulley was wobbling before and I didn’t notice it. :roll_eyes:

Please help! thanks!

Parts get updated and/or modified all the time

Recently, I installed a tensioner on one of my vehicles. The part is updated and looks nothing like the old part, but bolts up the same. My belt tension is correct, and the belt doesn’t wander

The fact that your crankshaft pulley is wobbling is cause for concern. The first thing I would do is make sure the mounting bolt is properly torqued. if it is, then you’re looking at replacing the pulley, aka the harmonic balancer.


The harmonic balancer (crankshaft pulley with benefits) is possibly/probably shot. It shouldn’t wobble too much unless the material between the hub and pulley is worn out.

P.S. That’s pretty bold to install a part that doesn’t look right. I hope that so much force was not applied to that balancer as to ruin it.

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How easy is to replace a harmonic balancer?

I am trying to figure out if I can do this job myself. I have a Chilton manual and by reading the instructions, it seems that the job is just swapping parts, however I have seen people talking about timings being off and stuff about keeping the no1 piston in the top dead center in other cars.

Is something is missing in the manual? I have seen a lot of people swapping harmonic balancers and they never talk about timing?

Don’t worry about the timing

Swap out the balancer and move on


You are right… I am going to take care of that balancer ASAP.

Okay good, thanks! :sunglasses:

You’re sure it’s bad?

You are sure that new tensioner fits/works properly?

This can be challenging for a DIY’er. The tough part can be loosening the bolt that screws into the crankshaft. Do you have a puller and a way to keep the pulley from turning? (You can’t hold the outside pulley part of the new balancer to keep it from turning or it can be ruined.)

Are you assuming the new tensioner is wrong?

We all know that updated parts often look nothing like the old part

In the case of MY new tensioner, it looked completely different, yet it bolted up just fine. And the pulley diameter wasn’t the same. But my belt tension is correct, and the belt doesn’t wobble

Anytime I even think a new part may be wrong, I spend some time researching it. And almost every single time, the part is correct, after all

How can you tell it is bad? Moving the harmonic balancer back and forth with your hands? Let the engine run without the belt and watch for movement?

I am not sure if it is bad or not. I cannot hear any rattling or squealing noises in that area. I just found it was wobbling. I was wondering if this wobble was caused by the new tensioner. This is what I read in Saturn forums.

The tensioner itself seems to be working fine, but you can see the belt moving in and out if you watch the surface area of the pulley. You don’t see this belt movement in other pulleys. This is how I noticed the crankshaft pulley wobbling because it is right below the tensioner in this car.

Some people in the Saturn forums recommended using nothing but the OEM tensioner, that the problem is not the balancer. Where in the hell am I supposed to get this? I am assuming ACDelco is the closest alternative, since they look the same (in pictures) but also cost tons more. The one I have is either Gates or Dayco, I forgot.

I am not assuming, I am just looking for answers. That thing about the tensioner causing the harmonic balancer to wobble, I read that in the Saturnfans forums.

Some people noticed the harmonic balancer was wobbling after installing an aftermarket tensioner, they wanted to replace the balancer but several users suggested that the problem was not the balancer but the tensioner and suggested them to use only OEM. After replacing the tensioner the problem went away.

I don’t want to spend a lot of money. If the tensioner is okay to use, I will keep using it. If the balancer is indeed bad I will replace it.