[Jake Raby]

Ok, compression and leakdown test results are in.. I have found some trend data that is leading me to believe the engine has a bent connecting rod.

Here are the compression and leak numbers:
#1= 270 PSI/ 19% leak down
#2= 235 PSI/7% leak down
#3= 230 PSI/5% leak down
#4= 220 PSI/7% leak down
#5= 235 PSI/7% leak down
#6= 230 PSI/7% leak down

The #1 cylinder was filled with oil when the spark plug was pulled for the tests.. A borescope test showed no signs of piston/ valve failure.

The high cylinder pressures of 31 are because the cylinder was pickled in oil, forcing the rings to seal off extremely, which is normal... BUT the high leak down numbers don't make sense as the leak down is entering the crankcase, as if the rings are not sealing.. This leads me to believe the engine had a failed AOS, it filled the #1 cylinder with oil and then hydro-locked thus bending the connecting rod. This would explain why dynamic compression is exceptional but static leak down is horrible.

The next course of action is to replace the sump plate, fill the engine with oil, replace the spark plugs and coil packs and then fire it up... If the engine has a rattle, we know its not the IMS bearing, because we know it is at stage 1 failure, but thats just a compromised seal.. If this rattle is found near #1 cylinder with the stethoscope then we can figure that the connecting rod is bent.

If the rod is bent, the engine will be issued a Death Certificate as the work to repair this on the 1-3 cylinder bank requires complete disassembly. If this is the case its a classic example of how an AOS can fail and create a secondary failure with enough collateral damage to kill the entire engine... Or the head could have cracked and dumped oil in the cylinder, or the scavenge pump on that bank could have failed, or, or, or.. it could be a new mode of failure we've never seen before.

So, after lunch we'll service the engine with oil, fire it up and see what happens... If it doesn't rattle we'll change the AOS then run the engine on the dyno, get it warmed up to burn all the oil out of the cylinders and then run a second compression and leak down test to see if the numbers on cylinder #1 are closer to those of the other 5 cylinders. Hopefully all 5 cylinders will be within allowable tolerances at +/- 10% differential across the board.

I'll report back...