Oil leak

Big Ed

Big Ed

N50247 - '79 Super D
Joined
Jul 20, 2020
Messages
1,938
Location
Tampa, FL
I flew acro last Friday for the first time in a few weeks. The next day I pushed it out of the hangar with my hand on the base of the strut. When I pulled it away, it was covered with oil. I had a pretty good mess. Oil was pooling in the bottom of the cowl and running down the side to the right gear leg and strut.

After discussing with my A&P, I bought an engine cleaning gun and a gallon of mineral spirits, and pressure washed every inch of the engine with it. Then I cowled it up and ran it for 10 minutes, then examined it closely.

Initial exam suggested the oil return line hoses as likely culprits. So today I replaced those, then went up and flew as few minutes of acro again. Landed and examined the engine closely. Bone dry!!
 
Yep, it's the little sucker at the red arrow below. Lycoming part number STD-1821: 2.5" section of 3/8 rubber hose. Pleasantly surprised at the price relative to many airplane parts: $10 for a set of 4.

I assume the heat in that location causes rubber to deteriorate faster? I would think replacing every few years is a prudent practice. From reading on the internet, most people try to fix minor leaks by cranking down tighter on the hose clamps, and wind up obsessing over the limitations of the clamps. IMO fresh rubber every few years is probably a less frustrating approach.

Zero need for any mechanical skill here; if you can repair your garden hose then you can do this. If not an A&P then get an agreement where you work "under supervision" and your A&P eyeballs it before placing back in service. I ran the engine on ground for 10 minutes and then inspected for leaks. No issues so went up and flogged it hard with some 10 minutes of acro and some inverted flight.


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I did it last year. Mine was a little less than ten bucks, but was not trivial - difficult to get in there on a couple cylinders.
 
Agree tool access could be tricky on the right side, especially if the hose clamp screws are not positioned to line up with an opening. I bought a couple of super long screwdrivers (36 inches) and extra long needle nose pliers with 90 degree tips for the next time. A little forethought when tightening the clamps should make the next time easier.
 
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