L98 knocking
09-03-2015, 07:22 AM
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L98 knocking Ive been called on to diagnose what sounded like a terminal engine knock on an L98 fitted to an Ultra 4
Background is thus...
Brand new crate engine. New camshaft fitted and the DOD removed initial fire up and run in seemed fine.
Off to the dyno for a tune.
Trailer the car home and then off for a proper test drive.
Warm up, get out on the road and give it a bootfull and then starts this knock.
Torn down to a short so far. Some metal in oil but very fine and doesn't seem to be bearing.
Noticeable wear on several valve stems but nothing really on rockers, lifters or cam.
But. There is evidence that it badly over fueling combustion chambers are black on one side and washed clean the other.
Plugs also seem to be quite a hot range as the electrodes protrude a fair bit.
Bottom end seems fine.
Any ideas ?
http://vid155.photobucket.com/albums...lo%20Knock.mp4
Background is thus...
Brand new crate engine. New camshaft fitted and the DOD removed initial fire up and run in seemed fine.
Off to the dyno for a tune.
Trailer the car home and then off for a proper test drive.
Warm up, get out on the road and give it a bootfull and then starts this knock.
Torn down to a short so far. Some metal in oil but very fine and doesn't seem to be bearing.
Noticeable wear on several valve stems but nothing really on rockers, lifters or cam.
But. There is evidence that it badly over fueling combustion chambers are black on one side and washed clean the other.
Plugs also seem to be quite a hot range as the electrodes protrude a fair bit.
Bottom end seems fine.
Any ideas ?
http://vid155.photobucket.com/albums...lo%20Knock.mp4
