[928uk] Thrust Bearing Failure

[go928]

Thanks Smiffy - Helpful advice as always.
 
I never specified the oil - they chose 5W-40 - but neither did I ask them to
check thrust bearing clearance.
 
Having said that, when I raised the subject of flex plate they told me that
they were very familiar with the problem, which also affects 968 tiptronics.
 
Cheers.
 
Graham.
 

-----Original Message-----
From: 928uk-bounces at lists.928.org.uk [mailto:928uk-bounces at lists.928.org.uk]
On Behalf Of Paul R Smith
Sent: 20 February 2012 00:47
To: 928uk at lists.928.org.uk
Subject: Re: [928uk] Thrust Bearing Failure


TBF is caused when the pressure from the flex plate exceeds the film
strength of the oil, so thin oil makes it more likely. If the engine had
10W-40 in it, did they chose that, or did you?
Did they check the thrust bearing clearance, or just release the flexplate
pre-load? 
Did you ever ask them to check the clearance? (This is where a 928
specialist is going to know what to do, but a "porsche specialist" probably
won't.)

A loose pinch bolt certainly suggests shoddy work, but didn't cause the
failure.

Cam sprockets wear. They will wear faster if the belt is over-tensioned or
loose. Was the belt tension checked, or just a guess based on the wear. It
the tension was checked, there should be a figure quoted.

ATF is an acceptable substitute for gear oil "if the correct grade is not
available", so ATF in the diff implies extreme laziness or incompetence.

I would suggest finding a few articles on flexplate TB checking, print them
out and show them to the garage. This will show them that it is common
knowledge amongst specialists that it is important to check the TB
clearance.
When they have had time to absorb that, point out how much money you have
paid them over the years, and ask them if they would like to make a
contribution to the repair replacement of your engine.

If you went to court, you would have a very difficult time proving that
anything they did caused the TBF or that anything they didn't do could have
been expected to have been done.

Smiffy


On 20/02/2012 6:19 a.m., go928 wrote: 

Late last year my S4 auto suffered terminal tbf - the engine is probably a
write-off.  

Briefly, I've owned the car about 10 years, covering about 6,000 miles a
year.  She has 130k on the clock.  Throughout the last 10 years she has been
maintained and serviced annually by the same firm and a flex plate check has
been specified at each service.  Over the last couple of years I have had a
series of problems with difficulty starting, stalling and uneven running.
She has been back to the specialist on a number of occasions and fuel pump,
MAF and ISV among other things have all been replaced.  Each time the
immediate problem has been resolved, but the car was not running quite
right, although it was hard to say precisely why.  I now suspect this was
early symptoms of the pending failure.

My view is that the Porsche specialists who look after the car should bear
some responsibility, but they do not agree and have washed their hands of my
situation.  Maybe I am not being as objective as I should be so I would
welcome any thoughts.

My reasons for blaming the firm who looked after the car are: 

*	Everything I have read about tbf seems to suggest it is unheard of
where the flex plate has been checked and released regularly. 

*	The engine finally seized only about 2,000 miles after the last
service/flex plate check. 

*	When the tbf was diagnosed (by a different firm) the pinch bolt was
only finger tight. 

*	The firm admit that they do not change the pinch bolt when they
check the flex plate. 

*	The cam belt rollers are damaged due to overtensioning of the belt.
(As they have changed the cambelt twice since I acquired the car, to my
mind, even if they didn't cause the damage they should have spotted it and
changed the rollers). 

*	ATF in the diff. 


The last two points have no direct bearing (ha ha) on the thrust bearing
failure, but do indicate a questionable level of care.

My questions: 

*	Is it fair to pursue the firm for a contribution towards the cost or
should I accept (as they claim) that the thrust bearing can fail at any
time, even if the flex plate is regularly checked? 

*	If I do have a claim, any thoughts on how best to get them to do the
decent thing?  I will take them to court if necessary but would prefer to
avoid all the hassle if possible. 


Thanks in advance. 

Graham 
(91 S4 auto) 



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