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Old 12-07-2018, 04:28 PM   #16
jeffnhiscars
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The tensioner has a bearing but the stamped idler pulley does not. They, along with the stamped cam gear, were prone to fatigue and fracture. I'd check for a split gear which would easily cause a thrown belt.

The "broken" belts I've seen has stripped teeth, but remained in place.
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Old 12-08-2018, 04:05 AM   #17
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Yeah tensioner is dead and on the piss
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Old 12-10-2018, 06:45 AM   #18
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Tensioner would also be my guess.
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Old 12-10-2018, 06:58 AM   #19
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M20 is hateful and committed suicide.

Time for a proper twincam
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Old 12-10-2018, 12:48 PM   #20
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M20 is hateful and committed suicide.

Time for a proper twincam
shut your whore mouth

Also, Simon, if you have all these pics and the part was new out the box, you can contact the manufacturer and they might compensate you for the damage
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Old 12-10-2018, 02:58 PM   #21
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shut your whore mouth

Also, Simon, if you have all these pics and the part was new out the box, you can contact the manufacturer and they might compensate you for the damage
I have the receipt and would love for someone to compensate me so I can get some head lol a WOT head to be specific ... ya filthy bastards
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Old 12-14-2018, 01:15 PM   #22
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Originally Posted by jeffnhiscars View Post
The tensioner has a bearing but the stamped idler pulley does not. They, along with the stamped cam gear, were prone to fatigue and fracture. I'd check for a split gear which would easily cause a thrown belt.

The "broken" belts I've seen has stripped teeth, but remained in place.
This snippet of information just cleared up a long standing question I had with the history of my engine. The timing belt had failed exactly as you said, stripped teeth. In my case it was on the lower crank pulley, which I imagine typically occurs during the initial start-up of the engine?

The low speed "break" would explain why my bottom-end made it out okay.
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Old 12-18-2018, 07:48 AM   #23
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Had it happen to a locals' car we just did a rebuilt head on. Tensioner failure.

Will point Varg to this thread, it also happened on his car, and have a customer car in the shop right now we did a head on a few months ago that is complaining about belt squeak. Varg just sent me pics of yet another local with the same issue.


Seems as we have a bad batch of belt tensioners?
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Old 12-18-2018, 08:04 AM   #24
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You are not alone, Simon...

https://www.r3vlimited.com/board/sho...&postcount=246
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Old 12-18-2018, 09:34 AM   #25
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I've worked on ducati motorcycles for many years and they use a similar timing setup with an adjustable tensioner. Over the years i've had 2 or 3 that pushed the belts into the timing covers and it was always a bent or mis formed tensioner. The pulley was not square to engine.

I wonder if this is what is happening here, a poorly formed tensioner bracket.
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Old 12-18-2018, 03:20 PM   #26
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OPs case is cloudy, he is yet to post any pictures of his tensioner area or provide any details on its condition. To wear the belt like that, from the outside in, the tensioner had to be stuck solid, unless it was rubbing on something else.

As far as the other cases go....bad batch of tensioners is pretty disturbing news.
I wonder if anyone with TB walking issues put the dial gauge on the tensioner and see how much play one has.
Typical reason for the belt walk is the overtensioning the belt. Too much tension can deflect the pulley (tensioner pulley) and makes the belt walk side to side. Did the installer make the spring do the job?
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Old 12-18-2018, 03:44 PM   #27
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The tensioner has a set spring, that's the perfect amount of pressure after a few rotations. The OP has been around the block with e30's. Perhaps it was a mistake, but I would be inclined to say no. The tensioner is merely riveted on the bracket. If they aren't stamped properly, the belt will slide off the pulley, just like a band saw, or sanding belt.

Very disturbing news. We warrantied the job here at the shop since we installed a rebuilt head, it included a timing belt kit we installed, and provided the parts. We always use Contitech, and have done so for a huge number of m20's over the last few years.
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Old 01-30-2019, 07:50 AM   #28
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any more reports on these issues or updates from OP ?


Just a heads up on ContiTech belts, I got one with my last order.
Anyway, my new Conti belt teeth were full of rubber crap/dust, a byproduct of belt teeth forming/cutting. I actually had to use stiff brush to clean all that shit out, about 1/4 cup full. Looks like all teeth got cleaned up and consistently shaped to the eye but I do not trust this belt and Conti quality control for their aftermarket cuz of this now. Used Conti for years on vw and bmw, never seen this bs.

PS.Anyone ordered Conti belts recently and noticed anything similar? You can't miss it, it will make a mess just by handling the belt.

Last edited by zaq123; 01-30-2019 at 08:02 AM.
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