LML Knock and 150 psi

ikeG

Oughta Know Better
Apr 19, 2011
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Western PA
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Got a lml in that makes a knocking noise. Balance rate on cyl 7 was 10. Had codes for that and cyl 6 injection timing. Compression test showed 150 psi on 7 and good on all the others. Could see piston top damage with borescope. Tore it down today to find this.
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NC-smokinlmm

<<<Future tuna killer
May 29, 2011
5,040
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At Da Beach
Probably just the pistons cracking. Look at the spray pattern, the chunks missing are right where the fuel is hitting the piston.
 

TheBac

Why do I keep doing this?
Staff member
Apr 19, 2008
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Mid Michigan
That piston was coming apart for sure. Look at that crack across the bowl from the broken out chunk. Ike, are there divots in the cylinder walls besides that one on the very top?
 

ikeG

Oughta Know Better
Apr 19, 2011
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Western PA
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Cylinder walls are fine except for the pics I took. Head is beat up but should be fine. I agree that a chunk of the piston broke out, and did the rest of the damage we see until it made its way out exhaust valve.
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