Cooked Piston? Damaged oil spray jet!
12-08-2011, 02:18 PM
#1
Three Wheelin'
Thread Starter
Cooked Piston? Damaged oil spray jet!
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?
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?
12-08-2011, 02:40 PM
#3
Rennlist Member
Casting flash from case or heads?? I always grind down excessive flash, usually some in the chain area of the heads. Sure chewed up that squirter!
12-08-2011, 03:36 PM
#4
Race Director
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?
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?
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.
12-09-2011, 02:23 AM
#5
Pro
Join Date: Aug 2010
Location: Finland
Posts: 529
Likes: 0
Received 0 Likes
on
0 Posts
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.
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.
