4-108 Starts fine cold, but not when warm

[rkurtz115]

My 4-108 starts fine when cold, but after motoring for 2-3 hrs. at 2200-2300 rpms it is difficult to restart immediately after shutting down. When you try to restart it sounds as if the compression is too low. It sounds as if it is turning over too freely. If I let the engine cool for 30-60 minutes, it starts fine.

[a64pilot]

Sounds like a vapor lock, except I don’t think Diesels are susceptible to vapor lock.
I would first start with valve adjustment. Contrary to popular belief, valves wear tight, and valve clearance goes away when hot, too tight, means leaking valves and low compression.
Plus it likely needs checking anyway and doesn’t cost money to do.
I like to start with easy and cheap first, before advancing to hard and expensive with trouble shooting.

[lonesoldier0408]

I second, the valve adjustments.