Cambelt "Wander"

[paultv]

I have a new water pump, cambelt, tensioner all fitted about 6K ago.

There's a constant issue with the belt being squeeky/screechy when the engine is cold - it comes from the bottom front pully - so I stripped out the belts and removed the bottom
harmonic balancer - now I can see the front edge of the cam belt has wear marks.

The noise is still present with all ancillaries and belts off.

So although the cam belt was "central" when fitted, it has drifted to the outer edge (front) of the gear train, and is obviously contacting the outer edge of the bottom main gear.

As the tensioner is new, any observations on why this occurs - idler wheel and associated lay shaft?

It's not the end of the world, giving the edge surface a touch of silicon makes it silent, but I'm not happy having the cambelt touching anything other than where it should.

Also if i turn the engine over by hand, at the front, the bottom crankshaft toothed cog/cambelt are really noisy - dry screechy belt sound.

So..... any thoughts or observations before I start replacing possible culprits.


Paul

[paultv]

Nobody?

Paul

[reggid]

could you have over tensioned the belt, they squeal like a .....if you do? the tensioners do go bad sometimes and might be throwing alignment off

[paultv]

Thanks for your comments,

Well I guess it's possible, but the tensioner and belt are new, well at least I fitted them after the head gasket replacement and top end rebuild over the winter - I'm beginning to suspect the idler which is original as far as I know - but have no time to open everything up and investigate - I've done a number of cam belt /water pump changes on E30's so have experience and don't think I have screwed anything up.

Paul

[stones]

Although it's new it could still be the tensioner, link to a post by Brianmoooore

viewtopic.php?f=2&t=277960&p=2955278&hi ... r#p2955278

and this one

viewtopic.php?f=2&t=267844&p=2894767&hi ... d#p2894767

HTH

[reggid]

belt rubbing on things when it shouldn't is a recipe for premature failure. at some point you would want to investigate further

[DanThe]

Ive seen several M20's with worn oil pump drive bearings, if the drive is pulled over to one side then the belt will move forward, but id expect to see a decent sized oil leak also. If the oil pump sprocket is the flimsy pressed type then you should replace it with the revised forged one

There is also the 'riveted' tensioner which could be the problem

[paultv]

Interesting, thanks guys, I remember that the oil pump sprocket looked pressed, maybe that's the problem, there's no oil leaks.

Time for it all to come out, at least it's been quiet since I applied a bit of silicon to the front edge of the belt, and the belt condition looks fine, so maybe it's a small problem. However considering the mileage I do, I best get it sorted.

Paul

[paultv]

I've stripped the front end out to replace the oil pump drive gear on my car car which is the old "pressed" steel type to upgrade it to the new Sintered gear.

Measuring the front to rear on the old worn gear shows almost 0.2mm diameter difference, the outer edge is worn smaller.

Meanwhile I took the cambelt tensioner out and found it wobbly and noisy - this after 13000 miles since the last install. So my question is:
I've always used Contitech belts and pulleys - these cost around 38 euro's for the set whilst buying the same from BMW is 110 euros - the Contitech is
always quoted as "OEM" but appears to be short on lifespan - Are the BMW items, whilst more expensive, actually better? Is the tensioner pulley equipped with
better bearings? or is the expense just a BMW price hike?

I'm not best pleased with finding this level of wear after only 13K miles - considering BMW suggest you change the belt and tensioner after 60K miles.

This'll give you an idea of the bearing condition:



I wonder if anyone has an actual BMW tensioner pulley - and could post a shot of it - I'm interested to see the difference - maybe non!

Paul

[martauto]

Sounds to me that the bearing (if there was one ever ! ) is about to let go mate !!
Throw it in the bin Paul.

Mart.

[paultv]

Yeah it's gone Mart ! New one feels fine, but then it's also the same product - so that's why I'm curious if there is in fact any difference between a 70 euro BMW tensioner and a 20 euro Conti one??

Nice day today, in the garage, radio on, mug of tea - fiddling with the car - pissing down outside!!

Paul

[martauto]

The quality of the bearing makes all the difference, I have worked on machines where the spindle bearings which have run for 24/7 were nearly 25 years old !
Maybe you get what you pay for ?
At home with beer .!!

Mart.

[paultv]

I reckon I might pick up the real thing from BMW whilst it's all apart and see how it goes

Enjoy your beer!!!

Paul

[paultv]

20190818_150005.jpg

I reckon I might pick up the real thing from BMW whilst it's all apart and see how it goes

Aaah, found one in my store, BMW packaged, Contitech belt but with BMW part # printed on it as well as the BMW logo

I wonder if the "cheap conti's " are cheap repros??

Enjoy your beer!!!

Paul

[martauto]

Beer is going well Paul
See how it goes mate .

Mart.

[paultv]

Here's the crankshaft drive for the cambelt - see how the shoulder is worn from the belt pushing up against it - caused a horrible screeching sound each time you stopped
the engine, and the old cambelt is worn on the outer edge.

main shaft drive_1.jpg

Paul

[paultv]

IMG-20190818-WA0000.jpeg

Old pressed steel beer bottle top oil drive
And new sintered item

[martauto]

That pressed steel one should not be allowed
Why did BMW even think about using garbage like this ?

Mart.

[paultv]

I agree - only thought I'd look into this as a result of information on here - it never occured to me that there was an alternative BMW "upgrade"

Mine measures about 0.4 - 0.7mm thinnner at the outside edge - probably responsible for the wear and damage to the main drive gear.

Anyhoo - it's all new and rebuilt - went out for a thrash - got rid of a minor oil leak as well - cam seal - even though it was replaced 23K Km ago - NEVER use anything but BMW parts for these critical items - you're just pissing in the wind for saving a few quid - then have to strip it all out again.

Lesson learnt.

Booger me - it's hot today!

Paul

[martauto]

Good advice Paul

Rather nice here in Leeds as well

Mart.

[steve_k]

paultv, where did you get the new pulley? also how much? just wondering as i know i've got to do an m20 cambelt soon.

[paultv]

I got it from Leebmann BMW parts supplier in Germany, it was 64 euros and well worth it, I found a number of pictures of the old "tin" ones that had fractured.

Try to check the condition of the main shaft pulley when you have the belt off as a precaution.

And a lot of cars have had them changed in the past.

Paul

[steve_k]

I got it from Leebmann BMW parts supplier in Germany, it was 64 euros and well worth it, I found a number of pictures of the old "tin" ones that had fractured.

Try to check the condition of the main shaft pulley when you have the belt off as a precaution.

And a lot of cars have had them changed in the past.

Paul

thanks for that

[paultv]

So here's the heap of junk off to be recycled, I'm hoping this is "case closed" for my little cambelt issue.

Next up the rear end trailing arm bushes as I find I have +40 min toe out at the back so that's no good is it??

20190826_123837.jpg

Paul

[TurtleDesignTech]

Hi Paul

I am glad you posted a thread about this. Currently have a timing belt squeak on my M40 engine E30 when at idle, once the engine has warmed up.

At least I know roughly what to look out for now.

Thanks

Harry

[paultv]

Squirt a bit of silicon into the bottom timing gear - if that fixes it temporarily, you may have a similar problem,

good luck!

Paul