audipwr1

Please let me know.

Also let me know if you know of a motor going with the bolts loctite'ed or tied off.

misterwaterfall

Do a search on here and you'll find some reports of issues with both loctite and wired. I believe they are the original versions that reported but the tied failures atually sheared off the bolt heads per the report.

modoz61

Mine werent the latest version but they were loctited and a custom 5 tab locking tab washer fitted

tore the heads of 3 Ti race grade bolts, 2 went out through the newly created hole in the cam cover and the other took a journey through the oil pump.

The resonance issue causing the backing out of bolts is what needs to be rectified first, or at least mitigated.

There is a link on RL for destructive torsional forces (nearly always on the first page within 997 GT3 forum) and a damper used to mitigate resonance

https://rennlist.com/forums/997-gt2-...cking-out.html

I have no affiliation with the seller but I have installed one of these dampers on my newly rebuilt engine before it turned over for the first time.

The damage internally due to resonance on mine was many and widespread, cams, pistons, cylinders, valve stem guides, lifters, bearings, flywheel interface to crankshaft, crankshaft and the list goes on, my story is in the link as well

That said I now do not believe rebuilding the cam actuators was the best option, the bolt holes were most likely galled from resonance and as such they should have been replaced. This would have only masked the problem until either they or something else/worse let go eventually, and something would have let go, the valve stem guides were ovalised to the point that there approx 0.001" between inlet and outlet valves in cylinder 6. Another shop also noted that the actuators are laser etched in alignment and they take this as a guide as to the accuracy of assembly of this part and do not recommend altering them in any way and if the bolts back out, replace them. Easy to say at $8K a set!

But as per above this isnt the problem, just the manifestation

audipwr1

Thanks for responses, i have not heard of a failure on the latest revision so am trying to understand if that has greatly reduced the issues

Please do share your information

That was a poll on failures, but they didn't ask if these were all on original actuators

Protocav

Do you know if the installation torque was increased when you changed out the factory actuator bolts for these Ti bolts and locking washers?

Jamie@dundonmotorsports

Improved variocam assemblies don't eliminate the source of the harmonic... If they don't spit out bolts to "release the stress" then something else will go.

Many 4.0RS had issues and many guys making 4.0L from 3.6L had issues with oil pump gears, and other "mysterious" issues until a damper was installed, then the oil pump gears stayed together...

mooty

why doesnt porsche fix the resonance issue once and for all ugh....

MC 968CS

From all the research I've done this is still an issue for the 3.8L and larger capacity engines. Not the lovely little old 3.6.

I assume thats still correct?

modoz61

Torque was slightly increased but as was pointed out to me by an experienced mechanic afterward the holes were possibly galled initially and this too should have been address rather than simply assuming the bolts had backed out.

Valid point in that the loctite wouldnt have had a proper binding surface.

But the astonishing fact to me was that the locking tabs were opened up, that would have meant significant torsional forces by the bolts attempting to rotate, this would no doubt have weakened the bolt heads as well.

All in all, not pretty but thankfully identified lots of other problems before they went catastrophically - although the bill wasnt small just the same