Porsche Enthusiasts Club Forum

After Mike Dowie took his engine out,



He was faced with the truth that he had indeed got thrust bearing failure in his 1985 S2. For anyone who hasn't seen what it looks like............those of a nervouse disposition and weak wallet, please look away.

I've seen it on Triumph straight 6 engines as well. On these it is the poor design that causes the issues. On the 928 something has to give, but you'd have thought that Porsche could have designed a better solution?

Blimey Steve Jones has just had this problem as well

Hi

With the sort of power my Nitrous produces, there was an obvious answer...a couple of spots of weld.... then no problems ever again....

All the best Brett

Hi Jim

Porsche changed a LOT of scrap engines under warranty in the 90`s due to this problem...they never did design a fix for it though...

All the best Brett

There are at least 2 permanent solutions from the US in shape of a clamp which fits behind existing flexplate clamp, preventing any forward creep of the torque tube towards crank.

Annual release of the existing bolt (and torqueing it to 10% over the spec in manual so 88Nm) also eliminates the risk. It is a very quick and easy job, though initially awkward on cars with cats as have to drop exhaust by an inch to remove rear bell housing bolts. After that first time you just cut the bolts down or omit them and then no need to disconnect exhaust.

The problem is that Porsche did not include in original annual maintenance schedule (but a check for condition is in the manual when torque tube installed). They couldn't subsequenly issue service bulletin to do it annually, as that lay them open to possible compensation demands from people whose engine was lunched!

Unless a 928 has been owned by enthusiast and/or serviced by experienced mechanic it's unlikely the flexplate pressure has been released. But if the end play is still within spec then subsequent annual release eliminates the risk (a bit like a few years after giving up fags your risk of smoking diseases reduces to that f non smoker!)

I have just suffered form this failure and I religeously performed my flex plate release & check every 12 months. It didn't save me here.
After talking this point over with PAul Anderson, it was noted that some cars suffer movement of flexplate movement after a few weeks or months and others don't suffer at all. Paul says he can't work it out as to why this happens with different cars & different times when the flex plate moves.

Having had to spend almost £5,000 on a replacement engine for my S4 this summer I have taken the radical step of spot welding the clamp onto the spline so it doesn't move - on Paul Andersons recomendation! He does this on all his race cars so he never sufferes from Flexplate problems.

Have to say the new engine is a dream to drive and kick-down is shear ecstasy - warp speed 5

Someone told me that this was only an issue on cars that have had the torque tube replaced. Anyone know if there is any truth to this?

Hi Mike

I seriously doubt that, as mine has never been changed (and I have most receipts from new)

As said...the ONLY real answer is a couple of spots of weld...it will NEVER EVER move again....

All the best Brett

And did your car suffer from TBF?

Just I read a comment on another board a while back as well that seemed to back up the statement by implying that incorrect torque tube replacement/repair was a possible cause but the poster didn't really elaborate.

Hi Mike

No, mine never has and now its welded it never will....

I dont think its physically possible to fit an incorrect TT to a 928.... but would need to ask Paul A next time I am up there.... which may be for HID lights...my brother has just had Paul fit them to his 84 - 928S...

All the best Brett

I thought this was only an issue on 928 auto boxes so why would Paul A do this on his manual box race car ?

Hi,

Is there anyway, either listening with Vehicle stethoscope or driving the 928 if TBF is happening or at risk please

cheers
Neil

Hi Neil

If you could near a noise with a stethoscope by listening near the rear bottom of the engine and IF you heard anything....then its too late and you are in SERIOUS TROUBLE....


This is all about PREVENTION really.... once its happened your engine is junk


All the best Brett

The engine in the pictures made no noise or showed any signs until it started cutting out when hot. When cold, she run as sweet as a nut........damn thing. I posted pictures in this forum from when I used to put mine on a ramp and release it every 6 months. There are tolerances, Adrian will know specifics as his memory is better than mine, but once your play is out of the tolerance then the engine is only good for a coffee table.