Randy_S

iTrader: (1)

Here is the breakdown. I got a 408 in December and have since put 3,400 miles on it. I broke the #7 piston somehow and dont know why. It has had no spray or a charger on it.

Does anyone have a clue how this happened?

Here is the link to the pix.

https://ls1tech.com/forums/showthrea...20#post7293320

pcf_mark

iTrader: (1)

I have a dead LS7 here with a very similar looking case of broken piston. I took it to a shop for a sanity check and they indicated it had over heated locally (steam pipe not connected properly or air pocket) then the cylinder got out of shape and closed up the end gap of the piston. Once the ring went solid it scoured the bore until it broke off a piece of the piston crown then all hell breaks loose. I am still disecting the short block now but it looks EXACTLY like that. You should check for a cracked cylinder wall - I have one.

I think the cylinder walls get distorted then the rings runs out of clearance forcing the crown to crack. The walls look thin in the LS7s. If you have a sleeved 408 this should not be the problem.

LS1curious

tear it down to a short block and get pictures of all side of the piston cylinder wall and rod as well as the wrist pin. also the rod bearing would be nice to see as well as the 2 mains surounding this cylinder.

blkvett01

Well i feel your pain! I had a new 408 with a hole in the side of # 7 big enough to put your head in it. It only had 800 mile when it let loose! So hope it gets better for you but these things happen to these motor.