24 bent valves - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Smallblock454 · 07-30-2015, 09:41 AM

Vario Cam is adjusted by chain lenght - so we don't talk about Vario Cam Plus, which works competely different.

Vario cam is not comparable to VVTi from Toyota or other cars. It's a Porsche specific design.

Vario Cam only adjusts cam timing on intake valves, not on exhaust valves. The solenoids that adjust chain lenght are electronically adjusted. The full adjustment only works at high rpms at approx. above 5.000 rpms.

So the Vario Cam theory doesn't work on that.

So what could cause that. For example if the plastic glider on the chain ramp is broken. So the timinig could be OK now, but when plastic parts came between chain and gear timing was wrong and caused the damage on the valves.

The only way is to tear down the engine and check everything.

Regards from Germany
Markus

Topless · 07-30-2015, 08:55 PM

I gotta go with Flaps and Marcus on this. VVT does not explain intake and exhaust valve damage. Now if you were on a spirited drive, spun the car clutch engaged, and allowed the motor to actually turn backwards, that would do the trick.

I like the ramp-material-chain-snag idea the best. Drop the pan and have a look around for big chunks of something.

jsceash · 07-31-2015, 06:40 AM

Quote:

Originally Posted by Smallblock454

Vario Cam is adjusted by chain lenght - so we don't talk about Vario Cam Plus, which works competely different.

The chain length is not adjusted (actually not possible). The solenoid move the slack portion of the chain towards the cylinder and away form the cylinder which changes the relationship of the intake cam to the exhaust cam.

Worn chain carriers on the vario cam solenoid won't do this either. They would affect the intake valves but not the exhaust cams as others stated and only one side.

I can't imagine all 6 cylinder having loose connecting rod bolt at the same time so that isn't it either.

My bets go for the main chain tensioner failing, the sprocket is loose on the IMS shaft as other noted, the scavenge pump on the side with the bent intake valve ate something, or the motor spun backwards.