Oil Drain PLug Gasket

[Joseph Munoz]

Can anyone tell me the correct oil drain plug copper crush gasket size for Lycoming 0-540 for my comanche. Many options available on aircraft spruce. Also am I correct in stating that those are once used then throw away?

[Clarence Beintema]

Hi Joseph,

There is normally no gasket on the drain plug, it should be a 1/2" pipe thread drain, either a plug or a valve. If you are referring to the suction screen gasket at the back of the engine, you require a MS35769-21 copper gasket. When you install it, the split in the copper faces the engine, you will also need some .032" to secure the valve. You are correct that the gasket is a one time use gasket.

Clarence

[Joseph Munoz]

Oh ok thanks. So is there another drain plug besides the suction screen gasket at the back of the engine. I witnessed someone changing the oil using that plug at the back of the ingine. Is it incorrect to drain from there?

[bernard nowlen]

you won't get all the old oil out of the engine if you use the plug with the screen as a drain port.

[9089P]

Hi

There is a drain plug at the bottom of the oil sump, about mid engine, on the co-pilot side. Most of those plugs have been permanently replaced with a quick drain valve making draining the oil a simple task. I'd recommend you do the same.

Don

[Joseph Munoz]

Thanks Don