Noises from pulleys and drive belts

[Al Gray]

My 1992 525i is making noises that seem to be coming from the pulley and drive belt area at the front of the engine. I can only hear it at idle and the noises are present on the initial start up as well as after the engine has been running for a while. The noises sound like a rattling sound. (No, there is no presence of rattle snakes or any snakes for that matter.) I changed all the drive belts recently within the last few months with no difference. Is it possible that some of these drive belt pulleys may be worn or maybe an idler pulley? Any thoughts out there would be greatly appreciated.

Al Gray

[Jose]

Al,

Try some WD40 on your drivebelts, if the ratteling or squeeking noise persists, check your chain tensioner.

[AZ_Jason_S]

I know my tensioner rattles. I can put a screwdriver on it and feel the rattle while the car is running. I asked my indy about it and he didn't seem to concerned.

[tim]

Soap (like ivory bar soap) is good for cutting down belt squealing in general. I don't like wd-40 for anything except perhaps bolt and nut removal.

I've seen idler and tensioner pulleys completely shot that didn't really make alot of noise. In any case it's a quick and easy fix. When they go, they make a grinding rattling sound. Like rocks in a tin can trailing behind your car.

I suggest a process of elimination. Remove the belt, and hand turn everything attached to it ('cept the a/c which you'd have to be a gorilla to turn when the clutch is engaged). Try idling with and without the ac on to see if its the a/c clutch.

From what you are describing I would be thinking water pump bearing (look for dried coolant residue), or power steering pump seal, or finally, an alternator main bearing. None of these is that bad. If I had to bet, I'd say water pump.

[Al Gray]

Tim,

I replaced the water pump and drive belts within the last 12 months. I'll try the soap thing first and if that doesn't do it then I will remove the drive belt and start checking the other components.

Al Gray










Soap (like ivory bar soap) is good for cutting down belt squealing in general. I don't like wd-40 for anything except perhaps bolt and nut removal.

I've seen idler and tensioner pulleys completely shot that didn't really make alot of noise. In any case it's a quick and easy fix. When they go, they make a grinding rattling sound. Like rocks in a tin can trailing behind your car.

I suggest a process of elimination. Remove the belt, and hand turn everything attached to it ('cept the a/c which you'd have to be a gorilla to turn when the clutch is engaged). Try idling with and without the ac on to see if its the a/c clutch.

From what you are describing I would be thinking water pump bearing (look for dried coolant residue), or power steering pump seal, or finally, an alternator main bearing. None of these is that bad. If I had to bet, I'd say water pump.

[tim]

My last laso water pump lasted 4 months and 5000mi. Some last forever. There's no telling. Did your new one have a plastic impeller? Anyway, if you see coolant coming out of it, that's likely your problem.

[632 Regal]

valve adjustment?

[Al Gray]

My last laso water pump lasted 4 months and 5000mi. Some last forever. There's no telling. Did your new one have a plastic impeller? Anyway, if you see coolant coming out of it, that's likely your problem.



Tim,

No, mine had a metal impeller. No sign of any anti-freeze leaking. I think it might be a belt tensioner or other pulley.

Al Gray

[MicahO]

Similar sounds on my 525iT had been from the idler pulleys The noises started with the onset of cold temperatures and got worse with lower and lower ambient temps.

The pulleys are something like $14 each from BMA, and they're an easy swap (well, as easy as the belt is anyhow.....).

[liquidtiger720]

could be a bad bearing in any of the pulleys.

mine had all dried out so i replaced all of them. ran me about 150 bucks. 1-2 hours of work to be done.

[Derek A.]

valve adjustment?

Can't adjust valves on an m50 motor.

The belt might just be noisy. About the only dressing I have found to work on belts is silicone. It will actually soften the belt up and reduce the noise. OF course if the belt is already dryed out - you might just want ot replace it, coule help keep you off the side of the road