My 35K mile 993tt had the engine dropped this week for it's UMW Stage 2 and Sachs Motorsport clutch upgrade. Sadly, it was noted that there was about 2.5mm fore and aft movement of the crankshaft. Sure enough as predicted, the #8 (thrust) bearing was shot and to make things worse, there is wear in the crank bearing shoulder - so I'm up for a new crankshaft and rebuild. There goes the early retirement plan.

So the questions I would like to pose are:
"Who else has had this problem?"
"How common is this?"
"What causes are know?"

I've had the car for 5 years and it has had a very tame life (akin to "the boy in the bubble" if you get my drift). I bought it as a six year old "near perfect" car although it had had a new clutch installed just before purchase at 14K miles. I guess that might have been a signal of a hard life initially? I am probably guilty of doing a percentage of my cold starts with the clutch engaged rather than having the car in neutral and clutch disengaged. I've now read that this can be an issue on the cold start as the trust surface is under stress with the clutch engaged, possibly at a time when oil flow is minimal. Perhaps it was a dud bearing in the first place?

In any case, I have to be philosophic and push on, but I would appreciate any comments as to cause, and prior experiences.

Thanks for your input.

Malcolm.

 

Is your car a 96 or 97?

 

Chris, it is a '96.

M.

 

Malcolm,

I've been seeing a number of these; both 993TT and 996TT's especially.

IMHO, the reasons are twofold:

1) Holding the clutch depressed when starting. The entire thrust load (the clamp load of the PP) rests against the bearing shoulders when lubrication is at minimum. For some people, we jumper the clutch pedal safety switch to allow the engine to be started without holding the pedal down. For the past 30 years, we NEVER had any issues with this (using far higher clamp load PP's, BTW) before the silly clutch pedal interlock was installed on all these cars.

2) Oil. Frankly, the 0w-40's and such light oils leave insufficient residual lubrication on the thrust bearing faces under the above conditions and its worse after the car sits for awhile. I like something heavier such as a 15w-40, 15w-50, or a 20w-50.

Hope this helps you.

 

Thanks Steve. I appreciate your comments. Perhaps it's a timely reminder to all to avoid the clutch in start. The vehicle's maual mentions this arther casually, but fails to impress upon the reader that this might be a very important part of proper care and maintenance.

Cheers.

M.

 

Hi Mal,

Im so sorry to hear about this. I agree with Steve on the oil.......I use Mobil 1 20W50 and I have always maintained a policy of starting the car out of gear. I hope it works OK for you.
Mine is in the garage at the moment as well. I am having a 24000km service and the boost controller is having a hissy fit! The car has spent this week on the dyno and it is boosting to 15psi and throwing out over 400hp at the wheels! Im getting a huge retardation at 5000rpm and it feels like someone has pulled the handbrake on. We are wondering about new ECU's or a trick external boost controller.......will let you know which way we go!
Anyway....keep me in the loop with your car, I would like to know how it turns out.
BR
Grant

 

Hey thanks Grant.

With the engine in bits I prophylactically have had 8 new exhaust valves and new all new guides placed. Now waiting on freighting a near new 996tt crankshaft from Kevin UMW with rods, and main bearings. A new 993tt crankshaft OEM here in Aus. is $9K and the only "good" second hand one available had had machining to the flywheel face and I thought best to avoid it.

So it will probably be a week before the parts arrive then a week to complete the rebuild. The right oil, clutch out/neutral starts, a kind run in for the engine and new turbos, and then we'll see what we have.

Still, its hard to look the wife in the eye without seeing that subtle shaking of the head!

Will keep you informed.

Malcolm.

 

Mal,

WOW - I must've missed this thread...

Sorry to hear about it - but it sounds like you have a good handle on it... those blokes in QLD better watch out when you get that baby on the track....

So are doing a full rebuild? A LWF and clutch is a big enough change let alone a fully rebuilt "NEW" motor. Who is doing the work for you ?

Dont worry too much about what the wife says - you should see the bill for my car right now - walls have a way of breaking things - LOTS of things...

Best,

Simon.

 

Simon, Simon, Simon....
I didn't know you were into demolition. Aghhh. That sounds terrible. Sorry to hear the bad news.
Still it did cheer me up slightly to know that I was not the only one suffering. Its a bit like the stock market - bad news everywhere.
Still, it's one of those amazing human traits that what's bad today never seems so bad tomorrow. We'll both be back stronger than ever!

M.

 

Mal,

Yes... it is one of my not very well practiced (but evidentlly I am good, I mean VERY good at it) traits.

Well it gives me the excuse to go Full GT2 conversion - you should see the wifes face when she sees all of the parts that just keep arriving....priceless.

Let us know how it goes - I am interested to hear more about the results,

Simon.

 

OK, OK........what is it with us and the looks we are getting from our wives? I am right there with you Mal, and Simon, I cannot even begin to imagine what you are going to have to stump up! I have a big new bill I am ever so proud of down at PR for the latest works to the 993 and then today I just bought a new Range Rover, but oooops! I forgot to sell the X5 and then to make matters worse, I bought a Norco full suspension downhill bike for no apparent reason! When my Mrs asked what the bike was for, I told her I was getting into shape to race the Porsche some more.........now we have very economic conversations around our place at present......oh well! Mal, I have a little plaque around my neck telling people to contact you if I have a heart attack whilst riding my bike! :-)

 

Is there something you're not telling us?

 

Chris, yeah, I forgot to mention I've added a couple of cylinders..... Ha Ha.
Make that 6 exhaust valves.
M.

 

Sad to hear about your guys problems down under. On the upside wifes do seem to take repairs better after being hit with them repeatedly.

 

i just read this post ..
why is it bad to start the car with the clutch in?
i thought the car needed to be clutch-in to be started?

from what i remember, my old 993c2 would not start unless it was clutch-in when turning the key.