Cylinder break-in

Bill Venohr · Post by **Bill Venohr** » Thu Sep 26, 2002 2:31 am

I just finished an annual where I replaced one of my cylinders with a rebuilt. I'm curious about break-in practices--my mechanic basically said to climb at full power, run at 75% power for at least 10 total hours, minimize power changes (and avoid cutting the power), and change the oil early and check the filter. Any other suggestions?

Post by **GAHorn** » Thu Sep 26, 2002 7:31 am

Do not minimize power changes. Make frequent power changes. But do run it "hard" (open throttle/high manifold pressure at low altitude, to insure high manifold pressure and good cooling) for the first several hours until the cyl temp drops and/or the oil consumption stabilizes. This high manifold pressure will place maximum pressure on the rings against the cyl wall and marry them up properly. "Babying" a new set of rings will allow the cyl walls to "glaze" and then you'll have an oil burner.
I prefer to use mineral (non-additive) oil for the first 5 hours or so until they break in, then switch to my regular ashless dispersant oil.

Alterfede · Post by **Alterfede** » Thu Sep 26, 2002 5:31 pm

I think i ve posted this before, but how in the hell

nobody never explained that, here in argentina, mechs and old pilots recommend to run the engines always at minimun power, explaining that doing this youll longer the life of the engine. Im thinking that ill have to do something to brake this "misteriometer" barrier, and show all that have been researched by manufacturers, owner, mechs, and pilots troughout the world. Wish me luck!!!

FEDE