Help! Piston is oval shape! I can see the rings

[thedsmguy]

A couple questions.


I took off a head for a friend last night assuming he had a popped headgasket. Turns out headgasket looks fine and the piston itself is ovaled on the front edge and I can see the rings /ubbthreads/images/graemlins/ooo.gif. He was getting massive blowby but I didn't really put it together in my head until I saw the piston.

There is some scuffing of the cylinder wall.

How do I fix this? Can I pull just that piston, and put another used piston in there? I'm assuming I'd need to put a new bearing on the crank, do I need to put all new bearings? How do I get the light scuffing out of the cylinder wall?

Thanks!!

 

[GVR4_1057]

That is a melted piston right there. You have to for damn sure replace at least that piston . But when mine did that it also scuffed the bore too badly and it took a full rebuild. This is not a small problem..............

 

[Rausch]

^ The bore will have to be bored/honed. If the piston is ovaled, odds are the bore is as well. Bearings very well may be fine, but that is neither here nor there, as you're going to have to disassemble it anyways.

Stock bore? You will almost definitiely have to go oversized with the replacements. It's possible that you could still stay within spec, but not likely. If it were me, I would just purchase oversized pistons and head out to the machine shop.


Edit: of you're good with a bore gauge and depth gauge, you can check everything out once it's apart. That is really the best way to determine what is next.

 

[HHIVR4]

I the cyl wall is scuffed I wouldnt bother trying to replace the piston and get by..It wont last very long that way and will probably cause more damage.

 

[fivestardsm]

Quoting VRausch4:
^ The bore will have to be bored/honed. If the piston is ovaled, odds are the bore is as well. Bearings very well may be fine, but that is neither here nor there, as you're going to have to disassemble it anyways.

Stock bore? You will almost definitiely have to go oversized with the replacements. It's possible that you could still stay within spec, but not likely. If it were me, I would just purchase oversized pistons and head out to the machine shop.


Edit: of you're good with a bore gauge and depth gauge, you can check everything out once it's apart. That is really the best way to determine what is next.




+1 Might aswell upgrade while your already tearing down! /ubbthreads/images/graemlins/wink.gif

 

[thedsmguy]

Its not my car, Its a friend/customers that just wants it to run. He's not modding it so he doesn't want to build it by any means.. Very weird, most guys come to me saying they want it faster, this guy just wants it to run good. He's only owned the car 4 days now and drove it for 1 1/2 day before this happened. So, would replacing the block with a running one seems like it would be a quicker move then to pull this one and take it to a machine shop, buy new pistons etc. etc.

YUCK!
And this all started when he thought he blew his turbo, then I thought it was probably a headgasket, now this sucks, I'm supposed to be moving!!!

 

[GVR4_1057]

^ Yup. Replacing the short block with a good used one is the cheap quick way to get him going again.

 

[toybreaker]

Be sure to check the fuel system out thoroughly before sending him on his way with a fresh motor.

Sending the injectors out for a cleaning/flow test would be cheap insurance against a reoccurance.

A clogged last chance screen in that fuel injector could have caused that hole to run lean, and damage the piston.