This happened to my friends 03 Lumina. After installing the heads and cam it was used for about a month and then he saw oil in the coolant. After removing the heads, both pistons 5 and 7 were badly damaged and the head chambers as well.
I suspect a lean condition in both cylinders caused by dirty injectors since it had an occasional miss, but wanted to have more opinions.

 

First of all those plugs are junk. I wouldn't put those in any car. I'm sure the coolant entered the oil through the crack ring land. And, the coolant entered through the damage on the head. I would say the injectors had to go to a really lean condition to cause that. It should have missed really bad with it running that lean. By the way cylinder 3 looked it was running lean too. Is it a stock cam or aftermarket cam?

 

Cracked or broken piston tops are the usual failure mode for detonation in GM engines. The banged up heads and spark plugs were likely a product of the broken pieces of metal flying around in the cylinder. So the question is: what caused the detonation? Certainly a lean condition under power could. But also timing errors caused possibly by a faulty sensor. I had a case of detonation and miss once when water leaked into a damaged O2 sensor cable shorting things out just enough to throw the AFR way off. Have you scanned for any current or pending DTC's? That might provide a clue. Also just wondering: he wasn't using any kind of FI or nitrous was he?

 

He use Torquer v.2 Camshaft 232/234 114 +4 & he didn't use any kind of FI or nitrous.

 

Too much timing and not enough fuel was the cause. Does the PCM have a custom Tune or stock tune??

 

 

fixed sorry about that

 

We've scanned it and it was giving timing retard of 2-5° at part throtle when the converter locked up. Otherwise on WOT I've not seen any retard. It did occatioally idled very rough and stalled, which shouldn't be he case with a mild cam. The block and liner are cracked on that #7.

 

03 Lumina?

 

Basic Holden like the GTO's etc but for the middle east. http://www.chevroletarabia.com/

 

That was a definite detonation and severe at that. Who tuned the car? or was it a stock tune?

 

The car wasnt on the bottle? Cracked ringlands definately make me think lean with severe detonation. It would have to be pretty damn bad to do this N/A.

Also, When did the NGK iridium plugs become junk??? I perfer the copper ones for price and short replacement, but i didnt think the IX were junk...

 

Might want to check the wiring and connector to the injector, and maybe replace the injector as well. I had a similar situation of randomly occurring knock and misfire on my '03 truck, and when I was disassembling the engine the injector connector fell off in my hand. Fortunately I was lucky and no damage occurred.

 

It was tuned by a knowlageable local guy. Part throtle was 14.7:1 and wot 13:1, and no notrous just driven hard 2 or 3 times.

 

Here's video for the car run with the problem & before we open the heads
http://video.ls1tech.com/video/f8f7a...ae010f027b.htm