piston/wall damage

[ivan300]

well i blew a head gasket so i popped off the head to find out the cyl 2 piston and wall are slightly damaged, this is a rebuilt engine with je pistons, less than 5k miles on it. The exhaust valves were black on this cylinder and white on all the rest. what could have have caused this.

what should i do?

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[drewvr4]

looks like is sucked something into the cylinder from the intake, look at the top right of the wall and the top right of the piston....def. something foreign

 

[Zex4g63]

Looks like you had a detonantion issue on that cylinder, better check the rest of them while its apart.

 

[talon4lifetsi]

Most likly the valves where not opening. The ones that where black.

 

[Zex4g63]

They are black because it was misfiring do to low compression on that cylinder.

 

[tbonitz301]

Looks like it got real hot in there. Are you sure this engine has only 5000 miles on it. I cant see any signs of a cross hatch. What was the cylinder to piston clearance when you fitted the pistons?

 

[talon4lifetsi]

He said on the exhaust side not on both.

 

[ivan300]

melted the pistons, stock 2gnt ignition is too advanced and the knock sensor didn't do anything.

 

[rb25det510]

Looks like it got real hot in there. Are you sure this engine has only 5000 miles on it. I cant see any signs of a cross hatch. What was the cylinder to piston clearance when you fitted the pistons?

which is very weird cause even motors with high miles still leave the honing marks.

 

[ivan300]

yeah the engine has less then 5k miles, i rebuilt it.

it was machined specifically 0.020 over for je pistons by a very experienced shop.


http://img511.imageshack.us/img511/5843/dsc00522ig2.jpg
http://img145.imageshack.us/img145/6198/dsc00521xa4.jpg
(also before you guys say anything the rings were clocked properly and were not all lined up when installed haha)

 

[mekal]

do you have stock valves and retainers?

 

[ivan300]

yes why?

 

[brassc2007]

It would have been a good idea to upgrade the valves and the retainers. With a new bottom end why risk it, you already spent the money a little more wont hurt. Depending on the motor milage the valves and or retainers for that cylinder could have been sticking or if the cam had a low side it could have been holding in the pressure and never releasing it causing the cylinder to detonate. The pressure has to go somewhere.

 

[talon4lifetsi]

Exactly what i was goin 2 get into.Did you look at the head and see what going on on there??

 

[e36bmer]

That looks pretty rough.