Guys,

I have a 2006 Cayenne S with 81,000 miles on it. Well maintained. Runs great. No significant problems and none with motor.

I drove it and put it in the garage after dinner the other night.

The next morning I turned the key. It went "whoomp" and lost all compression. The car is in the shop and they are searching for the problem. Timing is fine. Everything is spinning the way it is supposed to but there is no compression in any of the cylinders.

It's a good shop and they know their way around Porsches.

Anyone have a similar experience? Or have some thoughts?

Thanks!

Greg

 

Good luck with the diagnosis. I would think that something causing no compression would be pretty simple to diagnose. There can't be but a couple of reasons it would happen.

 

Are you sure it is loss of compression on all cylinders at once? Nothing mechanically binding? If so, sounds like a blown head gasket from the symptoms given. The most common of which is engine overheating. Have you have any overheating issues?

Need more information, however, I am sure your shop is already well on the trail of finding the root cause. Please keep us updated.

 

Thanks Renn Man. That's what I thought too. No temp issues and the leak down is 60-90% on all 8 cylinders. The factory guys are looking at it now. It's gotta be some kind of engine block failure or something. We'll see.

 

No worries. I know you said that the timing was fine, but did you check the timing chain? You could have bent valves in the valve-train that is causing compression to leak out. Once they pull one of the heads off a bank, I think you will have your answer.

Strange since these engines seem to be very low maintenance. Interesting to hear what they find. Any ETA on the diagnosis?

 

Renn Man. I should have an answer sometime today or tomorrow. I use an indie shop so I had to move the car to the dealer to get Porsche involved. We held off on pulling the heads before now because of cost, but now we're into that.

G

 

Also (forgot to mention), we checked the timing and it's fine...timing chain intact.

 

Any update on the issue? Curious to hear...

 

Update: My indie was unable to diagnose the issue...just suggest a new motor. I've moved the car to the dealer (Sonnen in Marin, CA) and they're going to have a go. I'm not encouraged.

Will update when this is resolved.

 

Greg,

Sorry to hear that. 81,000 miles sure is a young life to have to replace the engine. From what I hear, there are others with turbocharged 4.5s still going strong with twice as many miles.

If you have any more information that you think would be useful to other members, please share it. It would be great to establish some sort of pattern.

And of course, good luck!

 

Here's the latest: Engine over-revved due to accidental downshift (loaned the car to my daughter). Valves floated and caused very slight contact between exhaust valves and cylinders. Needs new exhaust valves and a look-over of valve-strain, chains, tensioners, etc.

Estimate coming. Stand by.

 

Greg,

Thanks for the update. Now this is making more sense. A mechanical over-rev is brutal on valvetrains and tough to avoid these types of issues. Trust me, I have been there before... Sounds like you are getting good advice to inspect the entire valvetrain since their could be stress damaged components down stream.

I suppose I can add another notch in my for suspecting compression leak from valves coming in contact with pistons

 

Female drivers....

 

well i guess we now know what will break these beasts. sorry for your costs.

 

How can you over rev a cayenne on a downshift? Doesn't the computers prevent that from happening unless you have a manual?

But if I recall, there were no V8 manuals for the 955?