[B25Flyer]

The Rocket has been slowly increasing oil consumption for over a year. I could see that the problem was on the left side of the engine based on the soot on the left side of the belly. The compressions are all in the mid-70s so it either had to be an oil ring or valve guide.

I flew to TX last week and in 4 hours I added 3 qts so I decided that it would not wait until winter, so I pulled the cowl and pulled the plugs on the left side.

#4 was oily so I pulled the exhaust. 2 and 6 were nice and tan and 4 was coal black and sooty, so I pulled the cylinder.

As the Cylinder came off pieces of the oil ring feel out on the floor.... There is a gouge in the ring groove where the broken piece was located. The cylinder looks good!!! I think a hone job and new piston will solve the problem....

1100 hours and everything else looks good, and nice and clean inside.....

Tailwinds,
Doug Rozendaal
F-1 Rocket

 

[pierre smith]

I'm curious....

...as to how and why an oil control ring can break while it's seated in the groove...hmmm.

Was the oil consumption good, early in the engine's life?

Best,

 

[B25Flyer]

I bought it with 300 hrs and it has about 1100 now. It has always used some oil, but it has been on the increase for the last year.

My Mech. said that this is pretty common...

Doug Rozendaal

 

[Walt]

Just an FYI, cylinders are usually replaced in opposing pairs (to keep the engine inertia forces balanced). If you do just one piston, you need to get one as close to the same weight as the one you are replacing as possible.

 

[B25Flyer]

The parts all came from Barrett and I am hoping they have a record of the piston weight and can match it....

Doug Rozendaal

 

[rocketbob]

...as to how and why an oil control ring can break while it's seated in the groove...hmmm.

Was the oil consumption good, early in the engine's life?

Best,

If there is a pronounced wear step on the cylinder at the bottom and top of piston travel, that can/does cause the rings to flutter and eventually break. Broken rings aren't uncommon.