Yeah but do NOT jump all over rrgrassi, he's talkin about Ford 460's anyhow.

Otherwise yer right, blown HG wont generally wont compress into oil and coolant galleries - but oil and coolant WILL seep into combustion chambers. Seen this myself with M180 inline 6. Meanwhile coolant bein more pressurized than oil fills the sump through entering oil passages and provides false readings on stick as if oil level aint dropping.

gdemoss tell us the truth, what exactly are you workin with here? Was the engine run outa oil and/or driven how long with blown headgasket? Gotta pull the head to inspect bores first thing. What the hell are you waitin for? Pulling cyl head on 616 is easy. Skip the compression test says me.

Meanwhile diesels do NOT rebuild easy. 22:1 compression ratio with 350 lbs per jug you understand. Backyard build might last 60k miles if engine's been severely abused. Personally, I will never buy an MB diesel where seller boasts of "rebuilt" engine. Gimme an original decent running Stuttgart engine and i dont care how many miles it's got.