C-12 what went wrong? Blown engine

x2 on cam follower.

 

C12 like the C13 are very trouble prone.Could be a number of things.

 

Well that was bad advice, general rule of thumb on my hands is when hearing loud noises turn it off right away if in a position that allows.

We had a Newer glider in our fleet with a Detroit factory rebuild with 250 on it split a piston and bust a valve just rolling down a flat highway. So much destruction even though shutdown.

Couldn't exactly tell what came first, the chicken or the egg.

 

A 2 piece piston. Looks like it grenaded a skirt, steel piston slapped around, pounding the liner and taking everything with it.

hypothetical thought

 

I'm not really seeing hard evidence of valve contact on the piston crown. For a valve contact to cause that kind of damage I'm thinking you'd see the valve imbeded into the crown and/or some hard valve marks on there too.

I'm thinking more along the lines of oil jet issue if the C12 has them. Piston gets too hot, expands too far, stiction and metal transfer between the skirt/liner. Boom! Failure.

 

Didn't hear about it much on the 2KS C-12, but was a known problem on the MBL bridge C-12. If you have ever had one apart, you would find the wrist pin is not retained by snap rings but a teflon plug. Plugs were believed to wear out, wrist pin get into liner, crack skirt, and the carnage begins. Overheated engines seemed to be more common to issue. Two I seen both were #5 cylinder and wiped out ECM so no data could be viewed. Both were during warranty and Cat took care of both.

 

The possibility could be, steel pistons are pretty hard. Takes a lot of force to shove something through.

If the valve did drop as there is a valve in the picture, or stayed down, would possibly cause the steel crown shove down on an angle, break the skirt, ventilate the liner as the piston continues to go up and down.

A piston on an angle with no skirt to keep it center is wider than the bore so would bust up the sleeve.