M156 reliability
M156 has head bolts and soft cam lobes to watch out for, plus other less severe issues. If engine replacement or major rebuild is in your budget, go for it. If not, watch out.

M157/M278 cylinder scoring, chain related problems, oil in harness and valve guides = engine replacement (scoring) or major relair (guides, chain, oil in harness)
M17x seems to be avoiding scoring, piston cracking and bad valve guides so far, but it’s early for this engine.





