Broken Valve Spring on the 3.6

[tholyoak]

Well just confirmed what I had suspected. The engine had devolped a tick in the fall.

Tore down the motor and found this on #3 intake valve


Don't think that using only the inner spring is closing the valve very efficiently
Oh well at least I confirmed that the engine had the cylinder update with the sealing rings done (it is a '90 based motor)



Oh well, now just to decide how much of the 'while I'm in there' disease I will succumb to it is already going from the 964 injection to the 993 MAF system....hmm wonder how much I can get a set of 3.8 P/C's for....cams?.... oh boy

Todd

[Jeff Alton]

I think if you get EBS to bore your cylinders and get JE pistons the 3.8 upgrade will be around 2000. Cams.... not sure if you can regrind the 964 cam, but new cams cam be had from camgirnder for around 600 i think. Regrinds, if it can be done, are around the 300 mark.

Jeff

[CBRacerX]

Todd,

Tough break. (Hey, somebody had to say it first!). Good luck with the upgrades, I'll be interested in how you might bump up the displacement. I've done the 964->VarioRam, so if you have any questions feel free to ask.

Cheers,

Chris

[Shuie]

Any idea what caused it? How many miles on the swap? Can things like this be detected without tearing the motor down?

Im getting ready to do a 3.6 swap and I dread the idea of getting a motor thats been overreved or is in need of an overhaul.

good luck

[tholyoak]

I think it was just fatigue that caused it. No sign of any other damage, don't remember over-reving the motor etc. I was pretty sure it was broken before I pulled the motor, since when I pullled the cover to see if the tap was just caused by a loose valve adjuster, it was easy to push down on the rocker and actuate the valve since with just the inner spring it is pretty light on spring tension.

Car has done about 12k miles since the swap, motor had a documented approx 95k on it when I got it. Obviously the top end has been apart previously, most likely warantee work by Porsche to do the cylinder head update.

Todd

[Shuie]

Pushing on the rockers is a good idea. Would a compression or a leak down test catch this?