Guess what I changed before this trip to FL? Checked records and did not find these had ever been replaced. 108k and they looked oem and were showing the tell-tale cracks beginning. We overlook this very cheap preventative measure, thought to throw out a reminder.


http://bmw.satservice.com/tensioners.jpg

I am surprised the pulleys are not made of metal

I am surprised the pulleys are not made of metal

they don't wear much. but i think it has something to do with dampening vibrations, as a reason for them being made of plastic

I guess none of you have experienced one of these failing? The plastic gets brittle from age, not wear. When it throws the roller, it then normally will take your fan blades with it. Then all of that spinning and flying debris leaves really nice marks on your hood, as well as wiping out all the plastics up front. If these have not been replaced on your cars, I would suggest doing so immediately.

The sound of one of these about to explode is very similar to a supercharger "whine" - only for about a second or two and then all hell breaks loose. You do NOT want to experience a fanblade explosion. That scenario will set you back almost $700 just in parts (not counting a hood which normally needs to be replaced. BEEN THERE, DONE THAT...

Hello

Thats a great prevntative messure as they do tend to build up play if fitted with tight belts. Also depends on how the car is driven and they tend to fail on high reved motors.

I am surprised the pulleys are not made of metalThere are some custom ones that want exploed! Too much to risk with the plastic IMO.

There are some custom ones that want exploed! Too much to risk with the plastic IMO.

you mean 'want to explode' or 'won't explode' ?

these are preventative maint items and should be changed around 90k or you will experience failure....

you mean 'want to explode' or 'won't explode' ?Will not explode within 150K Miles!

You have a link to use those custom ones with an 8er Eights?

The one's i posted will probably never expoled and as others mention will save you a bundle in preventive maintenance, Gerry at PhoenixMortorsports makes them complete with bearings anodized in the color you desire.

They are still only as good on the bearing they spin on.

Don't forget the tensioners because the spring shortens up with age.

True but i haven't seen a bearing fail, Only the plastic!

Plastic probably fails from the heat of a dying bearing. That would be the primary heat source unless in failing the bearing drags enough to slip the belt causing heat on the outside. Same root cause but a different failure mode:(

Hello

Thats a great prevntative messure as they do tend to build up play if fitted with tight belts. Also depends on how the car is driven and they tend to fail on high reved motors.


Mine failed at approximately 30 mph - I don't think that qualifies as a "high reved motor".

thats defiantley not high revs T.

Ive seen i happen to many small engines in the past and a few high milers.

Although i had a lose noisy NEW belt on my previously owned 190e 2.6.

from what I have witnessed, it's the plastic that ages and gets brittle. I have never seen or even felt a bearing loose or bad. Gerry's are neat tho, I think I will end up with those eventually. if you change this low cost item every 90-110k you will have no worries. watch one of my brand new ones blow up on the way to SE8!

from what I have witnessed, it's the plastic that ages and gets brittle. I have never seen or even felt a bearing loose or bad. Gerry's are neat tho, I think I will end up with those eventually. if you change this low cost item every 90-110k you will have no worries. watch one of my brand new ones blow up on the way to SE8!

knock on wood.

They are still only as good on the bearing they spin on.

Don't forget the tensioners because the spring shortens up with age.

The bearing in the anodized alloy pullies are replaceable and are only currently £15 a set. You have the safety of the strength of the alloy pulley with the economy of a replaceable bearing and if a bearing did go bad, the alloy pulley will never let go, just get noisier and noisier until the bearing collapses. If you ignore it that long you deserve the consequencies!

8Tech.

The sound of one of these about to explode is very similar to a supercharger "whine" - only for about a second or two and then all hell breaks loose...

My 91 - 850 make a short chirp sound just as I let off the accelerator, after I've had it floored, or when it upshifts (auto). I've always wondered what this sound was. Could this be the tensioner?

True but i haven't seen a bearing fail, Only the plastic!

Actually, it was the bearings that failed on my last E31 at 90k........and Terry's theory on the heat may be right.........

My 91 - 850 make a short chirp sound just as I let off the accelerator, after I've had it floored, or when it upshifts (auto). I've always wondered what this sound was. Could this be the tensioner?

Yes it could, when you unload the belt, the belt "whips" and if the damper is failing, the belt will go slack and chirp as it suddenly slips. More likely a tensioner failure than a pulley/bearing failure.

If the tensioner is excessively worn, it will increase the load on the pulleys so check them also.

8Tech.

Gerry.update your profile and prefs so you can get PMs plz... I want to put an order together. Better via the site?

Gerry at PhoenixMortorsports makes them complete with bearings anodized in the color you desire.

I'll take your advice on the preventative maintenance. Can you provide an address for Gerry at Phoenix Motorsports? Is he the sole source of the metal pully? Thanks,

Use the contact information in the top right corner of this Link.
http://www.phoenixmotorsport.co.uk/

Gerry.update your profile and prefs so you can get PMs plz... I want to put an order together. Better via the site?

How?:embarrasm

Up in the upper left of the top toolbar of this page....User CP, then, /settings & Options/Edit Options/messaging and notification/enable private messaging/checkmark by what you want elsewhere......... personally I like the enable popup notification if I'm here browsing the board, and it also shows first thing when you come back