24 bent valves

[Brett 986]

Thanks everyone for your thoughts.
The engine is a 2.7 standard issue.
Our first thought was was something done wrong when the ISM was done, but 7000 km since should rule that out I think.
When we put the car on the hoist the timing was the first check.
As Gelbester said there has been some magic because for all valves to be bent the timing must have been incorrect.
A suspicious person might fairly say that the mechanic is not being totally honest with what they found. But the mechanics are a straight up team, I'm confident I'm getting the real storey.
It's Sunday in australia today and I will be visiting the mechanic tomorrow for further discussion.
We used a scope to look into the cyclinder first and there was a sludge type stain on all cyclinder walls.
The oil was only 5000km old and still golden.
What is being said is that they seem to have these problems with the low km cars.
Thanks for eve ones ideas
Cheers Brett

[flaps10]

If it was timed correctly before, and is timed correctly now, and the valve marks are fresh then my theory is that you had a chunk of something take a ride around the primary chain that goes from the crank to the intermediate shaft.

It has happened before. In one case it was a rod bolt that came out. Could be a chunk of plastic chain guide too.

Either way, plan on that tear down

[mikefocke]

How much experience have your mechanics going inside and rebuilding M96 engines? How many Porsches are they working on right now? Are you better off buying a engine from a wreck? Or a rebuild from an expert?

I presume you know about Forums - PFA

[Gelbster]

Flaps - brilliant speculation !
The rod bolts are a well known weakness. I replaced all mine with ARP when I did the rebuild.
The need to pin the IMS sprocket is equally well known.
Looking forward to the"rouges gallery" tear down photos.

[Brett 986]

Hi all
Further update is
Once heads striped, not all valves bent
All exhaust valves bent and 2 inlet valves only.
No other visual clues.
Theory at this stage is the when starting the engine had a lean backfire and the engine rotated backwards .
The engine has VVT so I am thinking that this is possible.
Once the electronics don't know where the mechanical parts are we have problems.
I remember when I started the car I was in a hurry and when I heard it fire I let go of the ignition key, basically a tentative start.
This could have made the perfect conditions where almost start on a cold morning, just enough to kick back.
Is this a big stretch or plausible
Cheers Brett

[flaps10]

I'm not a fan of that theory. The vario cam solenoid only varies timing of the intake can to the exhaust cam. They don't wander. They are commanded to rotate above a certain rpm.

The exhaust cam is a slave to the rest of the can chains. You say the exhaust valves are all bent. Keep digging.