Chuck Z

Growing up, we had a HUGE strawberry patch and rhubarb that came back every year no matter how many times I cut it to the ground with the lawn mower!!! Good stuff!

Black Sea RD

Hi Chuck,

No way to really quantify how many thrust bearing failure (TBF) incidents have happened to 928 auto owners over the years. No such records have formally been kept kept by anyone and Porsche will never release this kind of data, if they even kept such data.

However it was enough to have Porsche issue a Tech Bullentin that TBF was due to improper TT R&R practices and not their fault back in the day.

We have also talked to more than just a handful of 928 owners who have had this unlucky experience.

There have also been more than a handful who have posted their TBF problems on this forum.

This discussion reminds me of the 996 Forums and their back and forth about IMS problems in M96 engines. Some 996 owners scoff at the problem and others post about their IMS mis-fortunes.

Chuck Z

Thanks Constantine. Lots of respect for all you've done for the 928 community!

Q: Is TBF failure more likely on 928s where the TT has been worked on?

I've seen several posts about failures but with the majority of 928s being ATs I cannot help but think it's not as prevelant as this thread suggests? If it were, wouldn't there be tons and tons of posts about TBF and folks searching for new engines?

I hear ya on the 996 IMS, had one, no issues.....

hacker-pschorr

If your shop thinks checking end play on a 928 engine is a lot of work, they should stick with $19.95 oil changes.

$600 or more to thoroughly check over an exotic car before spending 20 times that on the car itself sounds like a bargain to me.

"That deep"? Seriously? Pulling the heads to inspect the cylinder walls would be going deep into a 928.

What about a leak-down test? In other forums it's considered step 1 in a proper PPI. Not exactly a quick process either.

A good friend of mine considers a full alignment part of a complete PPI.

blown 87

I had lunch with another 928 owner today, one of his also suffered from thrust bearing failure, mine was in spec but was through the babbit and into part of the steel, his was .022 IIRC.

Constintine has a half bearing out of mine and both from Paul.

It is a real problem.

I doubt you will ever have a issue with it no more than you drive your car.

The higher the power, the more it is driven, and if driven hard, these are the guys that are going to have a problem if they do not address it.

Tom. M

Sorry... I'm JACA928O (just another cheap *** 928 owner) LOL....I don't need anyone to do a PPI for me... I'll take my chances...drive em hard..put em away wet....and if it breaks....I'll just rebuild or pick up another one...still enough bargains out there to be had... or using spare parts around the shop..I'll just cobble together something....

Chuck Z

....so, 5-speed cars are also a problem?

I see lots of 928s with 100k, 200k mi all the time, more than I hear about 928s with TBF? Sorry, I just can't help but think it's not that large of an issue... Is it more of an age related failure? Am I wrong?

You work on lots of 928s, so does Sean, so does Jim Burton and I've never heard Jim mention it and have never seen posts (don't always pay attention) from you (until this one) or Sean about TBF. Are there 928s that don't know they have a problem and if so, are there symptoms? Is engine failure eminent?

If it's that big of an issue, it could ultimately be the end of ALL 928s? No?

Black Sea RD

Hi Chuck,

Thank you for the kind words on our behalf. Same back to you for all you do for our community.

About your question, not really although some mechanics who didn't know what to look out for during a TT R&R have caused a few TBF'd engines. Very unhappy times for all involved...

There have been a lot of posts on Rennlist from owners who have suffered TBF problems over the years.

We also know some who are not on Rennlist and others who did not want to suffer publicly with their plight.

And Rennlist is a small universe of 928 owners. Since we have put out our shingle, we have been really surprised by how many non-Rennlist 928 owners are out there.

Kind regards,

blown 87

No, and I have no idea if yours is a 5 speed or not, if so then I need to edit my post when I mentioned your car.

Tom. M

just searched renny..... for "thrust bearing failure". Only 462 threads (and that doesn't represent cars that have had TBF)....

Total threads on rennlist 928 is around 66,000

so.. 0.7 % of the threads...

Im sure you can search for "crank end play"..not sure "TBF" would give accurate results

Question for the mechanics ...
how many tbf cars have you encountered in your years of working on 928s?

Im on the fence about "requiring" an end play check in a PPI.. For me it would be more of a "depends" answer..
Is the 928 an automatic?
is it a S4 or later?
how many miles?
has the torque tube or transmission ever been "messed" with?
what does the oil look like?
how does it crank?
what the hot oil pressure?

But if Hacker is going to pull the heads, do the end play check, check compression, do a leak down, and give it an alignment, and put it all back together after breaking the belly pan, exhaust bolts etc..for $300... I'm all for it LOL

Chuck Z

Thanks Constantine, how about the question regarding the likelihood of the problem surfacing after the TT has been messed with? Is it more apt to rear its ugly head on this car as opposed to one that has never had any TT work done on it?

Chuck Z

Thanks for all the other useful info in your post too!

tmpusfugit

A few observations as follows

Black Sea RD

We at Black Sea R&D don't have enough data to confirm this fact.

As a 928 community we do know that TBF does happen to mainly 928s equipped with automatic transmissions, there are known signs to look out for that can set it up to happen, like the drive shaft pullout at the front flex plate and there are a few remedies for this specific problem.

Because of this problem any work that involves the TT R&R on 928 automatics should be done carefully and the Porsche WSMs should be followed. A check of the crank shaft end play should also be done to confirm the health of the thrust bearing WYIT.

Cheers,

danglerb

PPI should be progressive, start with the most common easy to check items, and work your way toward the more invasive time consuming things, but stopping at some pre determined level of carnage.

What about checking the oil, MrMerlin often suggests dripping some oil on a sheet of paper and checking for shiny bits? Maybe pull the oil filter and cut it open?

The present situation with a PPI is a bit disturbing, but I don't see any solution other than the buyer getting a bit more education and telling the person doing the inspection what they specifically want done.

RE pie, German Chocolate pie is maybe my favorite, but as my FIL used to say, I only like two kinds of pie, hot and cold.