Andrew_955

Can you post the pics of what they found? Agreed that missing bits of valve seat will give 0 compression, while even a completely missing stem seal wouldn't affect it at all.

Libast

Yeah a stem seal would just cause your Cayenne to smoke out the driveway on a cold start.

theprf

The 3400 RPM is very suspicious. That's where the 996 switches from low to high valve lift @ light throttle. Just saying....

Here's some stuff from the 996 forum:
https://rennlist.com/forums/996-foru...ermittent.html
https://rennlist.com/forums/996-foru...us-lifter.html
https://rennlist.com/forums/996-foru...quick-fix.html

Magdaddy

this is what they sent me…

Magdaddy

was also the point that BOTH in tank fuel pump’s ran, during the drive with the Indy’s computer hooked up.

Ryanschoolya

Holy carbon batman.

I have nothing else professional to add. Hopefully a pro can help you out.

EricV2003

All I see is carbon build up no missing piece of seat... nothing a good cleaning and a valve job couldn't fix...

Andrew_955

I wonder if top left of the first picture is in fact a small piece of seat missing, could be carbon buildup but hard to tell. It's outside the sealing ring at least which is why you have more than 0 compression.

Either way all that crud is probably close to the point of not allowing a good valve to seat seal. Sealing face on the valve itself doesn't look great either.

​​​​​

theprf

That's an awful lot of carbon, I do not see any missing valve seat parts though. I suppose checking the demanded and delivered pressures of the DI pump might be in order to see if it's overfueling, and the PCV valve assembly to see if it's sucking oil.
Someone needs to take the valve covers off and check if the intake lifters are working properly. The valve covers probably need to be resealed anyway.

Magdaddy

Talked to the tech at length today…cylinder #8 is now the most frequent one misfiring, and not #1. There was some discussion about aftermarket readers mis-numbering the cylinders…but we agreed #1 right front, #8 left rear, sitting in the car, or #1 front left, #8 rear right standing in front.

Regardless…it’s done there, $$ TBD after the service manager sharpens his pencil.

Topend work isn’t something that anyone local does apparently, reaching out to shop’s awaiting the reply. Best way is to drop the entire front assembly…motor/tranny/Xfer case with the crossmember. Likely add the clutch, and motor mounts in the mix, if and when I can find a shop to do it.

Libast

Are you limited to just Porsche indy shops or are there some VW places near by? The platform is similar enough to the Touareg/Q7 you might be able to expand your shop choices.

Magdaddy

My go to Indy has been VW/Audi for as long as the brands have been here in the States…no exaggeration needed. They eventually hit the wall where PIWIS comes in, and the depth of digging needed. When I was originally considering one of these, and called to ask if they thought they could work on it…there response was simply, if you get one bring it by.

First one I got in Jan 2019, there and up on the lift it went. Yep, this is a Touareg…we can work on it.

But just like every shop, there is a limit.

My local Pcar dealer is discussing not servicing 1st Gen Cayenne’s anymore. Too many coming in with repairs beyond their value. Both Syracuse and Rochester, NY dealership’s literally have one master tech, and one apprentice. They are backlogged with the current stuff, actually making the money.

The 993, and the Boxster are being trailered to Ct for the suspension work, and that well respected Indy has a lot full of Cayenne’s in various states of disrepair. He don’t want anymore.

These Brute Ute’s are a hoot… but when no one can fix, or doesn’t want to fix em, that’s when the attraction starts to fade. Tomorrow I continue my literally 5 month quest to address that rough running issue. The saving grace is that it’s a stupid high spec 6MT, so worth the investment.

jbrowning22

Looks like a lot of carbon, but the valve seat looks intact.

I’d go buy a few cans of Mopar Combustion Chamber cleaner, and have at it. Then drive the **** out of it as hard as you can. You got nothing to lose at this point.

Magdaddy

so far, from multiple different threads it’s been suggested:
-Mopar Combustion Chamber cleaner
-Swepco 502, a few hundred miles before oil change
-Liquid Moly engine flush

Anyone used the above? I’m always hesitant using any additives like these…

As I continue to send the pictures to other shops, the answers are all over the place. One common response unfortunately, they’re not interested in doing the work. Special tools apparently for doing the V8 timing chains, as well as a HUGE lift table needed to handle everything coming down and out as intended.

Follow up with a couple more today. One suggested that if the top end indeed need’s to be done, he had concerns about the bottom end having 155k on it. I should consider getting a new “long block” from Porsche. A quick look shows NLA, but even if one was sitting on a pallet somewhere…how $$ crazy would that be. Still feeling like I’m going down a mis-diagnosed rabbit hole.

I need a shop to step up, and give me a second opinion on this. I’ll just keep expanding my search for that shop outward I guess.

jeff spahn

You don't have to have the special lift table to take the engine out. My indy in Chicago area took mine out with jackstands, tranny jack and two post lift when we removed to change the motor mounts and all rubber bits that couldn't be accessed with engine in. $1900 for engine R&R.