Hello everyone. I show the photos of the caterpillar 931 78U engine. How is it possible that the piston opened like this? I found the system to remove the oil pan without removing the engine. I can now work from underneath. But I don't understand how a piston opened and broke like this ...
I also wanted to ask where this bolt comes from, I really don't understand where it came from, everything else is intact and the bolts are in their place, it looks like a 14 key bolt..
No photos of the cylinder head.?
Ok
And the broken pieces of the inlet valve.?
Here it is
Looks to me as though the valve head snapped off and fell in the top of the piston in just the right way to split both the crown and the skirt open. Certainly an interesting failure mode for the piston. The valve not so much.
Ya told me to runner till she stopped.. If it was a stuck open injector there would have been A LOT more carbon buildup.. (& smoke) Looks like rust got to the spring and it broke, sending the keeper flying and dropping the valve.. Thanks for the pictures..& good luck with the o/h..
A fair assumption given the general levels of rust visible in the rest of the valve gear.
Seems pretty open & shut. Valve dropped, piston smashed it. Piston split open because of the valve being wedged into it.
I see that quite often in the PFR style pumps. (Cassette) And for the life of me I can’t figure out HOW the rust is getting into the oil system.?? Any ideas.??
The bolt you found came from the piston. These precup engines have a bolted in hotspot where the precombustion chamber shoots its load out onto the piston. I’m sure there’s a technical term for it.
What’s not technical about, “Shooting a load out.?” Lol
Ill ask the wife