My old boss in Phoenix swore by a specific torque sequence for Cessna 172 cylinder heads

He told me to always start from the center and work outwards in a star pattern, but to do it in three passes at 30, 60, and finally 90 foot-pounds. I followed it for years until a Lycoming service bulletin last month said their new spec is a two-pass method at 50% and 100% of the final torque. Tried it on a recent overhaul and the head gasket seal looked way more even. Has anyone else switched over and noticed a difference?

3 comments

3 Comments

roberts951mo ago

Got to clear something up here. That Lycoming bulletin is for their engines. The Cessna 172 uses a Continental engine, different maker. Their torque specs and sequences are not the same. You can't just swap one procedure for the other. @hugo_robinson25, you'd want the Continental manual for your cheat sheet. Using the wrong one risks a bad seal or worse. Always match the procedure to the actual engine model.

josephmartin1mo ago

Heard a mechanic say mixing up those manuals is the fastest way to an oil leak.

hugo_robinson251mo ago

Honestly my torque wrench skills are about as good as my parallel parking lol. But that new spec making a visible difference is pretty convincing. Might have to finally update my old cheat sheet.