E36 M3 timing chain whine.

[MLee 35]

Hi guys,

I recently replaced the primary chain-tensioner in my M3 (S50B30) with the chain-tensioner from an S50B32.

Apparently this is a common upgrade for S50B30s, and many other BMW engines that had early flawed tensioners.

The results were fantastic. Engine was smoother during all running, especially at lower RPM, and most of the rattles that could be attributed to VANOS noise were eliminated.

But now they've all been replaced by quite a distinct whine - which to me sounds like an overly tight timing chain running against a guide, not too dissimilar some sort of supercharger or straight-cut cam gears. Increases in frequency and volume with RPM and only began after changing tensioners.

Most people who have switched tensioners haven't mentioned resulting whine... Has anyone had any experience with this?

Worst case I'll have to go back to an original tensioner.

Cheers.

[MLee 35]

That's what I was thinking.

I've taken it out and reinstalled it once already as I thought that might have been the case... If the slot wasn't seated and was instead pressing against the rail it would add another 9mm or however deep the slot is to the tension.

But then I've also read that it won't be able to screw in if it isn't seated properly?

[euroriffic 607]

Might be a belt idler bearing starting to go and just a coincidence it's happened with the timing on the new chain tensioner? I'd try pop the two belts off and start it up for a few seconds and see if that makes it disappear

[MLee 35]

The chances are super slim, but you're right. I should check it.

Will do so tonight.

[MLee 35]

I did cop a feel when I removed it last... I'd say the guide moves approx 10mm with a small amount of pressure? Reasonably easily. I thought this would be about right.

[MLee 35]

Primary piston is fine, the secondary piston appears locked in to the first with the apparent circlip and spring assembly (as in it's still all in one piece). Oil passage appears open as new.

[MLee 35]

That's the one! I believe the cylinder which slides in and out of the main body of the right one actually consists of two cylinders which contain a spring and are secured together with a circlip.

Some people have had problems with the circlip having come undone while it was it was being shipped about.

http://www.bayareamotorsport.com/tensioner.html

[MLee 35]

Thanks for your help either way mate!

I changed the tensioner back to the old beast... Rattly chain again but no whine, so almost definitely the chain. I'll run it like this for a while until I decide what's going on here.

Maybe I'm just paranoid, but it was a decent whine.

Has anyone else done this to their S50B30? Or played with a B32 tensioner?

[KwS 2425]

as you know i did the B32 tensioner to mine. Replaced the 210,000km original one. Silent as a dead mouse.

how much wear/scoring is there on the end of the old tensioner piston?

[KwS 2425]

actually, does anyone have another B32 tensioner you could try? Plenty of googling has revealed a couple of other people with whine after doing tensioner (albeit on different BMW engines, but same theory). One of them said it went away after a drive (eek, risky) and the other said it went away when they tried another replacement tensioner. is it possible yours is faulty and is creating too much tension?

Alternatively if you havent already, try taking your B32 tension apart, thoroughly cleaning everything and reassembling? might now be complete together correctly?

Edited March 2, 2015 by KwS

[MLee 35]

There is a bit of wear at the contact point of the old tensioner... doesn't look too extreme though. What I'd probably expect from being 139k old. A little bit of wear on the piston also... But not quite as much as you had. Definitely rattles away with the old tensioner installed.

Even though it looks like SweetM3 has an Evo, I'll Pm him and see if he found any interesting noises.

Admittedly I did end up driving from the Kapiti Coast to Wellington and back on the new tensioner, wasn't too worried at first... But became more worried when it didn't go away.

B32 tensioner is clean as a whistle, although I haven't yet separated the primary and secondary pistons as I've read this is not usually meant to happen.

I'll try take a couple of videos comparing sound of old vs. new to see what you guys think.

[KwS 2425]

id be inclined to disassemble it as per the link you posted earlier, and reassemble and see if the tensioner operates better then. Could be something as simple as that circlip being slightly out of place.

http://www.bayareamotorsport.com/tensioner.html

[MLee 35]

I'm hesitant to pull it apart unless I need to, as I'm sure I've read somewhere that the ones that come apart during shipping don't necessarily go back together all that well? Although there are obviously plenty that people have reassembled and seem to work fine.

Not even necessarily a spare B32 tensioner to borrow (although that would be ideal)... Does anyone have one out of car that they can squeeze on and tell me how easily and smoothly the secondary piston retracts?

Mine seems to work - the secondary piston can be pressed in to the primary piston, albeit a bit notchy. I imagine this is normal as there seems to be a pretty hefty spring in there. But if anyone could confirm how theirs feels it would be a great help.

[MLee 35]

Thanks Dave, sounds like mine. I might be wrong, but I highly doubt the tensioner is faulty.

Have a listen... Maybe I'm just being paranoid. On second thoughts it sounds like it whines with the old tensioner too, but the new tensioner adds a buzzy saw-tooth timbre, and increases the volume.

Old:

New:

And new again:

Edited March 4, 2015 by MLee

[KwS 2425]

i had a quick listen before i went off to work, and ill have another listen after work but from what i heard, i didnt hear anything abnormal? Could be my speakers, so ill try some earphones tonight.

[MLee 35]

I'm not sure that the video makes it very obvious, but it is quite noticeable in reality. Maybe take out some of the bass? *doof doof*

I've heard a few other S50's on youtube that make a similar sound, so I'm considering continuing running it with the new tensioner and keeping an eye on it. Worn chain-guides, over-sensitive ears?

I've also seen other forums mentioning various BMW engines that whine with new/this specific tensioner. I'm starting to think it isn't a big issue.

Edited March 5, 2015 by MLee

[KwS 2425]

i think i hear what you mean in the second of the new tensioner videos (the one with the link), its especially noticeable as you decelerate near the end. Im sure i also hear it in the first one too, just not as loud or as much, but the test conditions in that video arent the same (revs arent as high or held as long). If you can do the same conditions as that last video for the old tensioner, i think you will hear it there too.

My gearbox had a whine that sounded like that in first gear, and apparently its fairly common in 3.0s.

[Allanw 1071]

I could hear a slight supercharger-like whine between some other noises.

Sounds like a Honda cambelt, when you don't trust the honda tensioner and do it just a touch tighter... then wish you hadn't, when you start the engine....

Are these things known to wear the sprockets a bit, maybe???

[MLee 35]

It wasn't very scientific was it...

I'll see if I can be bothered swapping them out again. In which case I'll make better videos under test conditions.

That's exactly right Allan, I hate these sorts of noises.

It could be... Although getting up in K's the motor isn't very old at just under 140k. It would have to be something to do with the chain/sprocket/guide assembly, I can't see how a fresher tensioner would make any difference to anything else.

I suppose I'm happy to run it for now on the basis that a bit of a whine is better than a chattering chain on deceleration.

Edited March 6, 2015 by MLee