mechanical tensioner noise?

[davem]

Hey guys got a question about my 95 325is (m50tu). car makes a chirping noise at idle, 1st gear, reverse that goes away at higher rpms. I've replaced both belt tensioner pulley bearings and belts with no change. My m50 uses a mechanical belt tensioner for the wp/fan/ps/alt belt and does not use the idler pulley found on many m50s.

looks like this:



Using a mechanic's stethoscope i think ive narrowed it down to the belt tensioner as it sounds like something is banging around inside the housing through my ear pieces.

has anyone ever had to replace the belt tensioner on their 24v due to noise?

[dsobering47]

Yes, those tensioners crap out all the time. Unfortunately you will probably have to upgrade to the hydraulic unit....I would go with ECS tuning for the kit they sell. I think its around $140, but it includes everything you need.

[davem]

Yes, those tensioners crap out all the time. Unfortunately you will probably have to upgrade to the hydraulic unit....I would go with ECS tuning for the kit they sell. I think its around $140, but it includes everything you need.

are they that bad? if it doesnt crap out really fast then id be happy replacing them with the same one. if mine is original then its already lasted 144k miles. only $40 for an oem one from BMA Parts and that's with a bearing so i'd have an extra one of those too. how do they crap out? seems like a fairly simple mechanism?

[e30rapidic]

I just replaced the actual black pulley piece on mine, the bearing had taken a dump.

[davem]

I just replaced the actual black pulley piece on mine, the bearing had taken a dump.

yeah i've already done that... mine was definitely worn but not bad. just on the fence about ordering the tensioner. i think i will, it's only $40 and comes with a new pulley bearing so ill have an extra one of those.

[drken]

Hey guys got a question about my 95 325is (m50tu). car makes a chirping noise at idle, has anyone ever had to replace the belt tensioner on their 24v due to noise?

You are on the right track. The chirping noise comes from the "pivot" of that spring loaded tensioner. The constant vibration of the serpentine belt on the pulley causes a little back and forth motion at that pivot, and it starts to squeak. I took mine off ( on a 528i ), and got a good dose of spray grease into the back side of the pivot. You can't really see it, as the back side is covered up, even with it off the car. It quieted down for a few months, until the grease dries out/runs out. I suspect that noise is one reason why BMW went to a "hydraulic" spring loaded tensioner instead.
You know, if you carefully drill a small access hole in the right place, you could probably stick one of those little red spray tubes in through the hole, and make it easy to "re-grease" once in a while. Be careful, don't hold me responsible, etc., etc., etc.

Good Luck!

Ken

[davem]

You are on the right track. The chirping noise comes from the "pivot" of that spring loaded tensioner. The constant vibration of the serpentine belt on the pulley causes a little back and forth motion at that pivot, and it starts to squeak. I took mine off ( on a 528i ), and got a good dose of spray grease into the back side of the pivot. You can't really see it, as the back side is covered up, even with it off the car. It quieted down for a few months, until the grease dries out/runs out. I suspect that noise is one reason why BMW went to a "hydraulic" spring loaded tensioner instead.
You know, if you carefully drill a small access hole in the right place, you could probably stick one of those little red spray tubes in through the hole, and make it easy to "re-grease" once in a while. Be careful, don't hold me responsible, etc., etc., etc.

Good Luck!

Ken

thanks for taking the time to share your experience. ive done a lot of research and found very little info, i guess the hydraulic tensioner set up is much lower maintenance. i was going to order the tensioner but now im thinking i might check if the local pick and pull has the hydraulic set up that i can scavenge parts from...