Knocking from drive belt area

[adamcontreras]

Hey all, I recently replaced my head gasket and of course some oil/coolant got on the drive belt. After installing everything I started the car and heard this loud belt squeal and some inconsistent knocking from the engine. I ordered a new belt and while I had it removed I started the car and it was as quiet as ever. Installed the new belt and it no Longer squeals but the knocking is worse!

I grabbed my mechanic stethoscope and the noise sounds loudest at the Power Steering pump. Has anyone here experienced this? At idle the pump pulley moves in and out like it always has so I don't think that's an issue. The car does have a Rotrex Supercharger installed but it does not sound as loud when listening there.

A/C belt is not installed during any of this as of yet.

Any help is appreciated, thanks everyone.

Adam

[pbonsalb]

It must be related to your HG job. Hopefully you did the HG right and everything inside and the problem is external. It did not knock before I assume so go back over your work. I once had knocking with a supercharger but it was a Dinan Powerdyne kit and the key that fits in the blower shaft and locks the pulley in place had broken. The Dinan has a dedicated blower drive using an extended crank pulley with extra pulley. The Rotrex drives from the main accessory drive and I don’t think the pulley is the same type but am not very familiar with them. I’d look at the blower drive and and tensioners.

[Eric93se]

If you have the mechanical belt tensioned check that its good , could explain all three belt slip, noise and overheat.

[pbonsalb]

I don’t understand the power steering pump pulley moving in and out, though the OP says it did before. If the pulley was moving in and out, the belt alignment would be wiggling rather than consistent. But if it did this before with no knocking then you would not think there would be knocking now.

I tend to agree wilth Eric93se that it is a belt tension problem. Just don’t know the source. A tensioner assembly is possible as is an accessory that is not bolted on correctly and allowing movement that knocks or results in slippage that causes knocking. A pulley or tensioner assembly not installed right is another possibility. Routing the belt wrong? If the supercharger or bracket was removed, not reinstalling with correct spacing or attachment points?

[Addamcontreras]

Thanks for the responses fellas. On my break today I’m going to pop the belt back on and see if I can tension the belt more or less by getting a socket on the tensioner and messing with it while it’s running to check for changes in the noise.

another thing is my power steering pulley has a bunch of belt remnants on it even though I just cleaned it when I put the new belt on.

with the belt off it’s dead quiet, I just don’t understand what would have changed since I don’t have to remove the belt to do the head work?

I’ll check the tensioners and pulleys again and verify nothing is coming into contact.

[pbonsalb]

Belt routing wrong? If wrong they might not provide the correct wrap to provide traction or take full advantage of the tensioners. I don’t have a diagram for an E36 with Rotrex. There are also some E36 with mechanical instead of hydraulic tensioners that may route differently due to one less pulley, but it has been years since I saw one.

[adamcontreras]

I've had the belt on and off that thing so many times. I drew a diagram I keep on my phone to make sure it's always routed correctly. That car eats belts though. Not too sure why but it drives me nuts. seems to need a new belt every few thousand miles.

From research it seems I have the mechanical style that seems to be spring loaded? It has the 16mm head to fit a socket on for releasing tension on it.

This is off the Active Auto site and how I have it routed. http://images.activeautowerke.com/pd...%20Routing.jpg

Not seen in the photo but about 80% of the SC pulley is wrapped with the belt. Alternator as well. Power steering only wraps about 40%.

If I can get a change by messing with the tensioner I'll order a new one. Maybe getting coolant and oil on it caused damage some how? If I can figure out how to post a video on here I'll do so later on today.

[pbonsalb]

I doubt the tensioner is damaged, but usually the black dust is from belt slip and belt slip can occur from insufficient tension or improper belt routing. Oil leaking on a belt can soften it up and eventually cause it to fail, usually by shredding ribs.

Could you bypass the blower to rule it out and use a stock belt or is that not possible without removing the blower assembly?

[adamcontreras]

I would need to remove the blower and its bracket to reinstall the factory hydraulic tensioner and tensioner roller. On my break I confirmed no noise with belt off. Reinstalled the belt and no noise was present for a bout 2 minutes until it started to warm up and the the knocking progressively got louder with heat. I applied tension on the mechanical tensioner and the noise would go away when tensioner loosened or tightned weirdly enough.

There is belt material all over the tensioner as well. I'm going to replace it tonight and see if that solves the issue. At the same time I'm going to clean all of the pulleys so they have no belt material on them and hope for the best. I was able to get an INA tensioner ordered for today.

I'm very particular about oil/coolant leaks on this car. Since I had the engine built 8 years ago I never let any leaks get out of hand.

I really appreciate your insight on this. I know you have a lot of knowledge on these cars and cars in general. I've seen your name on this forum for a very very long time.

Adam

[Eric93se]

Glad to hear your going with INA, was going to suggest it.

- - - Updated - - -

Rare for a belt to fit and be routed wrong.

[Floxer]

If one of the pulleys is moving in and out maybe it's doing that when the belt is installed, too. You could try if you can see it moving with the engine running and belt installed.

[Elbio]

Same issue here, knocking, using stethoscope the power steering pump seems to be the source. Hope the tensioner replacement solves the issue.

[pbonsalb]

Probably the PS pumps wear out with age and mileage. A lot of us have replace water pumps and alternators and tensioners and idler pulleys. I have a cold start squeak that seems to be coming from my PS pump though I am not certain it’s the source. Rebuilts for S52 are hard to find. You can rebuild yourself but I have not done the job. Are seals the only replaceable parts or are there bearings or rotors in there?