911 Rod

Call me cynical, lol, but image the one he would have come up with if it didn't start?

Rob Page

Looks like I might be reviving an old thread...

Considering taking on something like this, but with a 2009 Cayenne Turbo S. I have extensive DIY experience, but perhaps nothing quite like rebuilding a Porsche Turbo engine. Been looking for as much info as I can find on the subject, but as noted in many other threads, Cayenne engine rebuild info is hard to find/non-existent. Anyone around (@Jonathon Rolstin?? ) able to offer advice as to best places to go for how-tos, etc on the subject? Does Alldatadiy repair manuals give enough info?

Any reply would be much appreciated.

Jonathon Rolstin

well apparently I have email notifications on for this thread!

would be happy to offer advice etc. Factor Porsche workshop is what I used. I think I still have it and I would be willing to share. I’m surprised to hear of a turbo needing a rebuild - what’s failed (or failing) in the motor?

and thanks for the trip down memory lane!

JR

Rob Page

Thanks Jonathon. I appreciate you getting back to me.

To be honest, I don't even own the car yet. Diagnosis so far is an engine knock at idle, which sounds like it's in-line with the cylinder scoring problem that has been so well documented over the past years. Could it be something else, like timing or valve problem? Maybe, but it seems that the scoring problem exists in all engines up to and including the 2009 Turbos. Ultimate reason for this problem happening is still up in the air.

At this point, I'm doing as much diligence as I can before pulling the trigger to decide if this is something I want to take on, and also to determine what my purchase price point should be (ie. extremely low).

Your offer to share resources is fantastic, and I may take you up on that... More importantly for me is the information you had to chase down, because it wasn't mentioned or had poor coverage. (ie. Cylinder clearances, torque specs, etc).

theiceman

borescope should confirm bore scoring if its present. I would never buy a modern Porsche without one ...

Adamant1971

It's odd that the 4.5/4.7/5.0/5.4 928 allusi blocks almost never suffer from scoring. I wonder what Porsche changed to make this so common on later models.

The scoring can only be one thing really, piston skirts contacting the bore. Maybe it's just the tighter tolerances of more modern engines?

Imo000

I think it's the tighter piston tolerances driven by tighter emission regulations causes it. The 928 is a very loose engine. You will notice this as soon as you boost it.

theiceman

yeah really the very first i had heard of piston scoring in Porsches was this thread all those years ago. Oh how the world has changed.. not Just Porsche either, seems quite a few modern engines are suffering from this .

500

Colder climates definitely exacerbate this too...

I noticed when the new 9A2 engines came out (for the 992), the cylinder wall surfaces were changed to a plasma wire arc deposited iron... and I have wondered if that was (partly?) a move to tackle this issue in a more fundamental way.