F350 cracked piston

[Jokern]

Have a 350 with no compression on syl 6.
spark on syl 7and 8 wont come out

pulled the head tonight and piston is cracked on cyl 6
no mecanical cause to stuck spark, put on som solvent and check it tomorrow

what can cause cracked piston?

running lean?

[99yam40]

maybe water in cylinder could crack a piston.
is the rod also bent?
you say stuck spark, I guess that might mean spark plugs

[boscoe99]

Detonation would be my guess as to the cause of the damage.

What year F350?

[boscoe99]

Have you checked the ECU for codes?

[Jokern]

Thanks for replies guys

Can water in cylinder on a running engine cause this?
dont know abot the rod yet.
spark plug yes.
detonation, hmm

2008 mod i belive, flywheel, ECU and exhaust changed

have not checked ECU for codes, but no codes on display(tach)

[robert graham]

Just curious, but exactly where/what part of the piston is cracked? Crown area, skirt area, near piston rings?

[Jokern]

Just curious, but exactly where/what part of the piston is cracked? Crown area, skirt area, near piston rings?

Straight across the top

[TownsendsFJR1300]

There's a partial piston ring or valve seat imbedded in the top of the piston if you look close.

There's also some "impact" damage also to one side of the piston, on the top.

You have some other issues/damage is what likely caused the cracked piston

[99yam40]

I was thinking #6 was the lowest cylinder, and water ingestion up the exhaust maybe.
but I forgot this was a 8 cylinder, so never mind my other post

[99yam40]

There's a partial piston ring or valve seat imbedded in the top of the piston if you look close.

There's also some "impact" damage also to one side of the piston, on the top.

You have some other issues/damage is what likely caused the cracked piston

interesting.
the pic does not show the complete top of piston to see if there is a part missing to allow a piece of ring to end up on top, so maybe it is a piece of valve seat

[TownsendsFJR1300]

What it does show, (not even counting the crack) is very bad. Something came loose and cracked the piston with the head or valve.

A pic of the head would also be interesting..


Similar to a pic of my current zero turn mower (B&S) that spit out a seat and valve (common issue for the seat when over heated).
You can see part of the seat imbedded in the head(the top ring was squashed in the piston, but intact).

[robert graham]

Do these valve seats have any known history of coming off?….if so, why would that happen? …..

[TownsendsFJR1300]

Do these valve seats have any known history of coming off?….if so, why would that happen? …..

No idea for the 350 and we don't know yet if it even did W/O a FULL picture of the piston and head..


My "freebie", Toro (new head/piston and rings), 17 HP, B&S engine, the engines are known, for "over time" with little no air circulation (clumped up grass) spits out the exhaust valve seat (much hotter than the intake valve). Unfortunately, the exhaust valve struck the piston(broke in two), damaged the piston, destroyed the head however the cylinder was fine..

[99yam40]

No idea for the 350 and we don't know yet if it even did W/O a FULL picture of the piston and head..


My "freebie", Toro (new head/piston and rings), 17 HP, B&S engine, the engines are known, for "over time" with little no air circulation (clumped up grass) spits out the exhaust valve seat (much hotter than the intake valve). Unfortunately, the exhaust valve struck the piston(broke in two), damaged the piston, destroyed the head however the cylinder was fine..

I always use the leaf blower after mowing to blow the motor, oil cooler, and mower deck on the snapper Z mower we use for church grounds mowing.
I need to look up how old and how many hours it has on it, but I think it is 20 years or older .
it has been a good mower, but you have to take care of them.

OP needs to post up a better pic of the piston and a pic of the head also

[TownsendsFJR1300]

I always use the leaf blower after mowing to blow the motor, oil cooler, and mower deck on the snapper Z mower we use for church grounds mowing.
I need to look up how old and how many hours it has on it, but I think it is 20 years or older .
it has been a good mower, but you have to take care of them.

Sorry for the de-rail...

Mine is 16 years old and absolutely, it gets an electric blower taken to it after every use. The PTO was changed in 2015. It was sitting along side a guys house, which I noticed
(never being moved). I asked about it, said it "was broke,, take it."..
After digging into the locked up engine, found the exhaust valve inhaled (two pieces) and valve seat gone seat, piston top damaged badly. A new head, piston/rings, and a carb/battery, runs like a top. Replaced some pulleys, bearings, etc. I later went by and gave the guy a $50.00 Been running it for a year, love it!