Why does the head gasket keep blowing on a Komatsu WB140-2N with a Yanmar S4D106 engine?

[Robert M.]

I'm working on a Komatsu WB140-2N with a Yanmar S4D106-1FH engine, and I'm completely stuck on a head gasket problem. The machine runs and drives great, but after a few hours of use, the head gasket blows again - always on the same 3 cylinders. Has anyone here dealt with repeated head gasket failure on a Yanmar S4D106 engine before? I'm trying to figure out what could keep causing the same cylinders to fail even after all the machine work.

 

[James R.]

If it's always blowing on the same cylinders, I'd start looking for a warped head, liner height issues, or a crack in the block or head. Repeated failures in the same spot usually point to an underlying mechanical problem, not just a bad gasket.