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Discussion Starter · #1 ·
I have been always impressed by the technical skill and knowledge of the M5 members. So here I turn for help for something quite unexpected with my '02 M5.
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:crying2:At just under 80K mi the double pulley tensioner broke off while driving about 50mph. The flying tensioner punched a 1.5” hole in the radiator, bent the Crank Pulley and the spinning fan got entangled with the belt and took out all the fan blades which also went flying around the engine bay cutting holes on the power steering and radiator hoses.<o:p></o:p>
<o:p></o:p>
Here is the kicker....The cause of the flying tensioner is that the tensioner mount broke off from the lower timing cover. The stealer says the lower timing cover must be replaced which requires removing the engine from the car and pulling the cylinder heads, cost will be $8,900. <o:p></o:p>
<o:p></o:p>
Has anyone ever heard of this happening? I think there must be an alternate way to mount the tensioner or replace the tensioner at another location with a different style and/or re-route the belt. The car runs perfectly with the exception of no cooling, alternator or power searing.<o:p></o:p>
<o:p></o:p>
:1zhelp:Any advice / ideas on how to approach this problem would be much appreciated.<o:p></o:p>
 

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First of all,sorry to hear about your problem.

The lower timing chain case can be changed without removing cylinderheads and engine from the car.Even upper chain cases can stay!

T-stat,vibration damper and water pump have to be removed.
The bolts on the bottom are all removeable after removing the lower oil pan.

The dealer quotes the BMW repair manual TIS.
It says to remove all that stuff.

But this is BS.

I know that it works my way as I have done it quite a few times...

If the dealer does not want to repair it that way,find a good BMW indie who can do it...

BTW,is not a popular failure....
 

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Bugger that!

You can change the front cover without removing the heads and with the engine in the car - there are several threads on replacing timing chain tensioners that cover this, just takes a bit of lateral thinking rather than following TIS.

And the cover is "only" $466. I reckon I could do the job in 8 hours or so.

HTH

PS Bloody Raikku beat me to it again :)
 

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Case repair

Though obviously dependent on the exact nature of the extent of damage to the lower case, I would be
very surprised if I wasn't able to repair the case itself.

A competent machine/welding facility with TIG equipment and an oven (for preheating prior to welding
and subsequent stress relief after repair), would likely be more than able to accomplish a perfectly
satisfactory repair. Cost should be well under $150-200 range.

Regards,
Alan
 

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Discussion Starter · #5 · (Edited)
Thanks ALL!

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As I thought... I found several good threads on removing the lower timing cover. <o:p></o:p>
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Looking at the alternator bracket, where the top tensioner bolt goes, there appears to be plenty of metal to possibly mount a different kind of tensioner and still have a similar belt routing. I was thinking of using one that has a single bolt mounting point that rotates about the mounting point. I might even be able to use the old style double pulley set up. I'll let everyone know which way I go. <o:p></o:p>
 
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