A friend with Cummins M11 engine removed his steel drain plug from the engine’s aluminum drain pan to change engine oil.
I saw ALL the threads come out when the plug was reinserted. Now he had a serious problem.
I think it may be impossible to prevent eventual thread stripping, even by using a torque wrench to install a drain plug. Aluminum is just too soft to hold perfect threads over many years of removing a steel drain plug several times a year. I think all M11 owners should carry a new insert, drill & tap, so when it does strip, parts will be available for a tech or owner to install as the coach will be down until the right parts can be found.
Rubber expansion plug was first used as an emergency plug, but later it was learned that expansion plugs do not work. A few years ago, a Foretravel owner’s expansion plug slipped out with hot oil burning his fingers. So a better solution had to be found.
Cummins drain plug inserts part number 68749 ($49), drain plug part number 3055069 ($10.80) and brass washer part number 67946 ($2.90) was purchased. Drain hole drilled/reamed out to 1-1/4″ and NPT tapped, insert installed with Loctite and now there is a new steel hole to accept a steel drain plug.
It seems that there are two styles of inserts, with and without a shoulder for a wrench. Shoulders are preferred because they can be wrenched into place, locked against drain pan and can be held in place when removing the drain plug, to prevent the insert from coming out with drain plug. Cummins part number now does not have a shoulder, but we were told that Cummins used to have a shoulder insert.
Photo shows insert with the shoulder.
by Barry and Cindy 1997 U270 36′
Replacing your drain plug with an Engine Oil Drain Valve