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YOUR RESEARCHCooked Piston? Damaged oil spray jet!
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Use robots
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I have seen the vid about the engine build at Porsche, and they use robots on some parts.
Leading evidence: 'Use robots' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Use robots' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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While taking some bearing measurements I discovered a small problem!
Underneath a crank bearing journal the piston cooling jet for cylinder #2 was badly damaged.
There was a small aluminum (not ferromagnetic) shard embedded in the jet. It measures about 5mm x 2mm x .25mm and was lodged into the jet enough to require tweezers to remove it, in other words it didn't just "fall out" on it's own. No idea where that shard came from! Someone mentioned perhaps a manufacturing defect.
Once the shard was removed, I can see the hole appears to be totally damaged and is nearly completely welded shut, certainly severely limiting or even preventing oil spray for the #2 piston. You can see the damage clearly on old vs. new (and other functional jets).
Could this be the root cause for the (overheating and subsequent) oil fouling in cylinder #2 where it was the worst? And perhaps because of it's proximity and heating affects on #1 and #3, causing premature wear and failure or loss of oil control in those cylinders as well?
It is certainly a possibility. Being able to hook up an external oil pump and compare the output from that jet to those of the others could help one make a more certain determination.
While the flow looks to be restricted, generally the oil delivery produces a surplus of oil and what limits the amount of oil is the size of the actual jet or orfice that aims the oil at where it should be aimed.
Porsche claims the oil jets lower piston temps by 50C (122F) which is no small amount of heat considering the oil may already be at nearly 200F or even more in places.
I could imagine that if the piston was indeed receiving inadequate oiling from the jet due to the shard of metal that could be at the root cause of the engine's troubles.
Sincerely,
Macster.
For some reason, I'm having a hard time to believe that the shard would have came from the engine internals.
I would say it was on the jet when it was installed in the engine.
I have seen the vid about the engine build at Porsche, and they use robots on some parts.
