Quote:
Originally Posted by cstreit
Well I found it...
#1 Rod bearing spun. Almost completely gone, nothing left but a paper thin shell. The crank bearing surface checks in spec, tomorrow I'll check the rod for ovality. Certainly the damage on the other bearings is as a result of the loss of oil pressure because of the spun bearing.
Now, why did the #1 bearing fail. More than likely because of a couple missed shifts in the last 3.5 seasons and a few 'caught it' money shifts. The bearing just slowly broke down untill the loss of oil pressure caused it to fail completely.... ...however I'd entertain other ideas!
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Generally speaking, #1 or #6 rod bearing failures are due to dirt in the system.
Debris and dirt, from anywhere in the system, will lodge inside the crankshaft passages and since the crank gets oiled from each end, thats where it remains to do the damage. One also finds such contamination inside the case oil passages which is why each & every oil galley plug must be removed at overhaul for proper cleaning.
The crankshaft oil passage plugs must get removed and everything scrubbed out when you find such things (as well as at overhaul time).
FWIW,....when 911 engine starve of oil (provided everything is nice & clean), it causes failure of the #2 or #5 rod bearing as thats the last part of the engine to get oil.