Detonation
Or does it happen when its cold also...?
You should take it for a drive when its cold...let it warm up for at least 10 minutes of driving.....then do a smooth WOT run. See if it DOES NOT detonate.
Then:
Wait till its all the way up to operating temp and then do a WOT run and see if it DOES detonate...?
If it does it only AFTER its hot....then your pistons are all gummed up with burnt oil thats stuck onto the piston. After the engine gets HOT that oil starts producing little hot spots that pre-ignite the fuel as the piston is still coming upward, before reaching TDC, thats the detonation.
Detonation kills the rod bearings by crushing them and then you have engine failure from a snapped rod. The rod is moving upward when the fuel/air detonates before the spark plug fires and causes the explosion...which tries to push the piston back down when its still coming up....so the rod bearings take a beating.
I had this exact issue. I pulled the heads, cleaned the VERY nasty pistons and the problem was 100% gone.
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Last edited by LS6427; Jul 28, 2015 at 09:24 PM.
Or...remove all 8 spark plugs and fill each cylinder with SeaFoam liquid and let each cylinder soak overnight to try to eat the oil away.
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