rush

Girlfriend has a 2000 pontiac grandprix gtp "supercharged" car has 60k miles syn. oil since new changed every 5k miles .anyway she starts car oneday and its missing badly buddy looks at and #5 plug electrode is bent, heputs new plug in runs fine but has taping sound now,I listen to it sounds like tapping under intake but hard to tell, so I pull valve cover off pull the roller rockers off see no prob. pull supercharger off "spin it" sound ok, pull lower intake off "has roller cam ck lifters ok maybe piston broke? I'am pulling head tomorrow. Any ideas?
Thanks Pat.

Vinny P

If the electrode was bent, something hit it. Most likely something is in the cylinder and now may be embedded in the head or piston. I work on alot of Gm 3.8 liter engines, unfortunetly, none are supercharged. So I cant offer you any insight to specific problems with supercharged engines. I dont know of any similiar problems related to this on the non-supercharged engines. For the most part, they have been good.

rush

Thanks for the reply, I have worked on them too and had very little prob. with them, something embedded sounds about right.

Vinny P

The question is.. what got in there any how did it get there? Is it possible a piece of the supercharger came off? I guess you will know when you get it apart. Good luck.

jeff32

3.8... In the top ten best engine worldwide.

Mike Paula

Somthing bent the eletrode. I am wondering if you lost a valve seat.

rush

Thing is, it runs smooth after the new plug just tics.

rush

THREE BROKEN PISTONS!! WTF, this car has been treated like a baby, now I wounder what caused this? and how can I keep it from happining again? their all broke in the same spot, upper right about half inch in and 1 inch wide.

Vinny P

Can you post a picture? Are the breaks in line with the spark plugs? Maybe detonation?

rush

all 3 pistons are broken like this right where intake valve is,they are broke down to the top ring like they where hit with a hammer. "sharp edges"no burn look, all pistons are black like they are getting enough fuel,lots of nicks in #1 piston,proly from the piston.