Cracked Piston

[87gnturbosix]

I'm putting my engine back together and found a cracked piston. Would this crack cause a light knock. The knock sounded like the knock the GM pickups make when you first crank them up. I haven't found anything else in the engine. Does anyone have a stock turbo piston they would like to sell?

 

[wants a tr]

i'd have them all checked...the stock pistons are prone to crack where the 2 different types of metal meet around where the wrist pin goes...I dont know if thats the right termilogoy but hopefully you understand.

All 6 of mine were cracked after some serious detontation...

 

[Hacksaw]

That picture shows the crack at where the long part of the skirt begins.

Detonation & overheating can cause piston cracking. Overheating can come from both coolant flow and oil flow problems.

You may already know & have done this, but:

Check every piston very carefully for wear (mic them, don't just throw them back in!) AND cracks. Also, check the cylinder bore the cracked piston is from. You need at least 4 internal mic readings to check a bore: 2 @ 90 degrees apart at the bottom, and 2 90 @ degrees apart near the top of the bore. The cracked piston could have caused some weird wear after it cracked. Too loose a piston in a bore can also cause piston damage.

TRW used to have a big lineup of stock style pistons, but I don't know there status in the auto parts field now.

Fully grooved main bearings will help oil flow to the rod bearings and cylinder walls. Main bearing #1 tends to be looser on the V6 from the factory for some reason. And if you don't have a improved oiling system, it may be worth upgrading it.

-Mike H.

 

[1FASTV6]

I have a set. Pm me if you are interested.