Quote:
Originally Posted by gottajalpa84
bad news...I believe i found the actual source of the problem.The oil pump that is driven by the cam (above the bell housing) "seized" and sheared off the keyway between it and the cam.That is what likely caused the timing to screw up and in turn allowed the exhaust valves on the opposite head to hit the pistons..(all 4 on the one head were making contact with pistons but it appears 3 are ok but may be bent.)I am now looking for a new oil pump and key.Is this oil pump strictly for cooling the oil? cause i looked at the oil pressure and it was normal befor i shut er down.
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Correct, the cam driven oil pump is only for the oil cooler.
As for the connecting rods being problematic, there is no concrete evidence of that. If the con-rod that “chewed” on your valves is still straight, then that should be a testament of excess strength and if it is bent you can’t seriously blame the con-rod.
To the best of my knowledge the con-rods are “sinter-forged”, which as a rule of thumb has 90% strength of a regular rod, which in turn is easily compensated by a 10% cross-sectional increase.
Interestingly Porsche 944/951 (and probably other models as well) have both cast and “sinter-forged” con rods and Porsche allows a combination of both in the same engine. On a major Porsche discussion board the “sinter” part of the description has disappeared, so owners there recommend to use the “forged” rather than the cast rods without having any evidence of the relative strength of the two.
Laust
04-24-2008, 11:06 AM
