oil seeping out intake pipes

prkaye · #1 08-19-2014, 02:45 PM

I have oil seeping out my intake ports, some worse than others. The AME next door said this is not normal, and could be a worn valve guide, although this would be very surprising with only 217 hrs on the engine (O-320 from Aero Sport Power).
Pic attached. Any thoughts?

az_gila · #2 08-19-2014, 02:55 PM

Is it really from the intake tubes, or is it seeping downwards from the oil return tubes?

prkaye · #3 08-19-2014, 02:58 PM

Then big ones (such as in the photo) are the intake pipes, right? The AME (A&P) suspects oil might be running down the inside of the intake pipes and seeping out those rubber seals, as shown in the photo.

Mike H · #4 08-19-2014, 05:41 PM

Time to find a new AME. If oil were really leaking out of this joint, as in oil coming out from inside the intake tract, you would have multiple issues, such as massive intake leaks, oil fouled spark plugs, disappearing crankcase oil.....

That oil is running down the intake tubes and puddling in the seam of the intake tube coupler sleeve. Look for weeping rocker cover gaskets or oil return lines.

vic syracuse · #5 08-19-2014, 05:57 PM

Yes, the oil return lines that are right over the intake tubes are notorious for leaking. Look closely, and the hose clamps are probably either loose or overtightened.

Vic

rocketbob · #6 08-19-2014, 06:21 PM

I use automotive spring clamps on the oil return lines, and since they maintain tension they don't leak. Throw the hose clamps in the trash...that's why you never see them used anymore in cars.

prkaye · #7 08-19-2014, 06:31 PM

not sure i understand, please clarify. Are you saying that it's a leaking oil return line that is dripping oil down onto the outside of the intake tube, and there it is running down the intake tube and pooling on the coupler sleeve?

Quote:

Yes, the oil return lines that are right over the intake tubes are notorious for leaking. Look closely, and the hose clamps are probably either loose or overtightened.

If I understand correctly, the hose clamps are on the intake tubes, not on the oil return lines... not sure i understand what you are saying here.

Kyle Boatright · #8 08-19-2014, 06:34 PM

Quote:

Originally Posted by prkaye

not sure i understand, please clarify. Are you saying that it's a leaking oil return line that is dripping oil down onto the outside of the intake tube, and there it is running down the intake tube and pooling on the coupler sleeve?

Yes. Very common. Check your return line hose clamps. They are probably the most common source for oil leaks on Lycomings.

You'd need two failures for oil to come from inside your intake tubes. Failure 1 = an oil leak into the tubes. Failure 2 - a leak around the hose connections to the intake tubes so the oil escapes the tubes.

jimbo · #9 08-19-2014, 08:15 PM

This is peaking my interest. If it is the oil return line to rubber hose connection that is leaking what's the best way to stop the leak aside from just tightening a loose hose clamp?

Dbro172 · #10 08-19-2014, 09:51 PM

Is it leaking, as in physically dripping? My O-320 from aerosport has had oil sitting at that intersection since I took delivery of it one year ago. Now have about five hours flying it and it looks the same.

I think the oil came from when I removed the temporary plastic spark plug hole plugs and preservative oil dripped and flowed down the intake pipe. Mine is brand new and looks exactly the same.