shantybeater said:
Well from what i've come across they all make the IMS rattle, some more prominent than others, but the volume of noise does not correspond to a problem, unless that is it suddenly gets a lot louder in a short space of time - correct me if i'm wrong Ken
Timing chain noise can range from very low to very high on these cars. Have over 280 turbo cars on our books and frankly the 997 make more noise than the 996 - which is funny since components were changed in the 997 to reduce the noise.
Frankly I wouldn't worry about it. The chain adjusters don't go wrong - it is a spring under tension and we have replaced these on the more loud cars without any improvement.
Again the plastic guide rails just don't go wrong. As mentioned we did receive a car after a rebuild had been done that had excessive chain noise but that was done to the guide rails being put in upside down - an easy mistake to make if you don't build these all the time.
So what does that leave...
well the sprocket for the cams
and the intermediate ring/gear
timing chains
The sprocket for the cams - unlikely although we have seen the slipper rings disappear from usage, but even then noise level seems unaffected.
So it leaves intermediate ring/gear - we have seen damage to the ring on an engine that had noise at idle but upon picking up the revs went away.
Timing chains - really unlikely
Think it is very difficult to be certain. You can rebuild an engine with all new chains, adjusters, rails and it is still as noisy. We have also on one of our own 996 turbo engines used 997 turbo chain related parts to see whether that made any difference - very little.
It is a little like excessive oil pump noise - is it the oil pump or the intermediate gear? Could be either that is the problem. Same concept, you take two turbos and fit a LWFW - one will be relatively quiet and the other loud despite using all the same parts and installation method - no real reason.
Just think some engines are more noisy than others.
Ken
