greggmorton

Sounds familiar. Check my thread. I’ll keep you posted on my progress...

deilenberger

Hi.

Just sort of stumbled across this thread, and was curious - the engines that failures were observed in - what their production date was? 2010-2011?

There are two Cayenne threads that might be of interest: https://rennlist.com/forums/cayenne-...cam-bolts.html
And: https://www.6speedonline.com/forums/...s-failure.html

A bit more went on behind the scenes encouraging NHTSA to convince Porsche a recall was the right thing to do.

Thing is - the old bolts were replaced with new aluminum bolts. The problem wasn't the material the bolts were made of - it was the design of the bolt. The ones that failed had an anti-tamper pin in the center of the Torx recess. Swaging that pin in place while making the Torx fitting put some stress into the aluminum that caused failures where the head attached to the shaft. This problem was limited to the 2011 V8 engine'd Cayennes (a few early 2012 also may have had an issue.) Funny thing is - BMW was using the same manufacturer (the variocam adjusters were not made by Porsche - and neither are yours) anyway - BMW was experiencing the same failures on some of their engines that used very similar Variocam adjusters made by the same manufacturer. BMW issued a "Campaign" so when one of the cars showed up for an oil change, it took a bit longer than normal since the bolts were changed.

The replacement bolts were made of aluminum, the way to tell bad from good was to see if the bolt had the anti-tamper pin in the center of the Torx recess. If it did - bad bolt. If it didn't - good bolts.

I imagine ANY engine using this sort of Variocam (or whatever they want to call it) device made by the company that made them for everyone, made during that time period would suffer from this sort of failure.

That's why I'm curious about the date range for engine manufacture - wouldn't surprise me to see the same range as the V8 Cayenne engines.

lawlence

At least yours starts! Mine turns over but won't fire. I'm like a month outside of the 4 year warranty... of course...

okie981

The two cars are both GT4s, so the earliest they could have been built is early 2015.

But interesting info on the Torx head bolts in the Cayennes.

aryork

If the OEM bolts break on the track (think worst-case $15k repair bill), I wonder if 4.5L conversion 1) is still possible and/or 2) costs more? Maybe that's a question for Rick. I don't recall him saying they replace the valves for the conversion, but maybe so.

lawlence

My GT4 suffered the same failure recently. The photos the dealer sent were nearly identical to those in the OP, including a sheared bolt lodged in the same location. The use history of the car fits the description in first post as well by the previous owner. The car was meticulously maintained and failure happened at around 7800 miles.

All the bank 1 intake and exhaust valves were bent. There were metal particulates in the oil filter when disassembled. Porsche ended up replacing the bank 1 cylinder head and camshaft actuators on both banks. The valve cover got damaged from the sheared head bolts flying around, so they replaced that as well. The engine was fully flushed with the oil pan pulled to ensure there was nothing stuck in the oil pump pick up screens. It would've been great if they had replaced the whole engine, but I think the miniscule amount of particulates wouldn't do any long term damage, especially knowing that the bolts are soft aluminum. They had my car for about 6 weeks.

No idea if the new part was updated. I will be putting in steel bolts after I put a few more miles on the car to ensure there are no lingering issues from the engine-out procedure. Porsche was gracious enough to good will the repair and my local dealer and SA went to bat for me. I had only owned the car for about 3 weeks before this happened, and the car was just outside of the original manufacturer warranty.

I don't think I'll be so lucky next time. Replace your bolts, folks. Especially if you track your car.

TDT

Wow, sorry to hear this, but at least it got sorted by Porsche.
Makes me glad I did mine a couple months back.... hopefully will dodge this bullet.

okie981

Can someone post a photo of the Torx socket of one of the OEM bolts, ideally one that hasn't failed?

Luca Paindelli

Here's a picture of the intake cam sprocket that incorporates the variocam actuator. You can see the Allen steel bolts that Rick used before reassembling our 4.5...

okie981

Thanks, good pic of the sprocket and new steel bolts in pristine condition, always helpful to see the parts in question, but I was seeking the same view of just the head of the OEM aluminum bolt.

Luca Paindelli

I should have them back in a couple of weeks when the car is done...

BGB Motorsports

Hope this helps!

okie981

Thanks. Are those the steel bolts in the sprocket on the right or the OEM aluminum ones? The recessed part of the Torx portion is too dark to see if there is the protrusion-like feature mentioned in the earlier post of this thread.

Spyerx

Wait. Porsche had same issue of cam actuator bolts backing out on the 997.2 gt engines.... fix is higher spec bolts and red loctite.
guess they haven’t learned.

aryork

So I am reading that Porsche used the same parts that failed to fix your problem - is that right? Doesn't that seem strange? Maybe there has to be a TSB or something like that issued for them to do anything different than an OEM repair.