Oil Leak

[Jbroz04]

We have a cherokee 140 with a O-320 in it. It was overhauled in June to factory specs. It is under warranty as well. After flying today noticed a oil leak in two spots. Both leaks were coming from where the oil line enters the cylinder. It was cylinders 1 and 4. It was leaking at the blue joint that is threaded on. Was wondering if this is something we should send back for warrenty work of if the blue joint just needs tightened.

[Roger, Roger]

The blue fitting may need tightened, but in my experience something more common is the plate covering the end of the cylinder (known as the rocker cover). The gasket that seals that tends to leak. I would have your mechanic check those fittings and tighten the rocker cover and see if that does the trick.

[Jbroz04]

Well another thing to add is that it looked as though oil was coming up through the blue fitting immediately after shutting down the engine. You could see alittle puddle on top the blue fitting. I guess that could have dripped down from the rocker seal though. Are the blue fittings pressure fittings or do they have o-rings in them as well?

[Roger, Roger]

Originally Posted by Jbroz04

Are the blue fittings pressure fittings or do they have o-rings in them as well?

The blue fittings are just pressure seal, no O-ring. All that they are is drain oil from the rockers and the valve stems back into the sump. Because of that, there is very little pressure on them, so I would think they'd have to be very loose to actually leak. But I don't know, they could be. I do know that pretty much every single engine we have come into the shop has at least one rocker cover that leaks a little bit.

[trafficinsight]

The blue fittings are called "AN" fittings. They seal by virtue of a flare on the tube and the end of the fitting.

In that location they're not under pressure as it's the gravity oil return from the rocker box.

[Jbroz04]

We noticed a little oil around the blue fasteners before the flight so we tightened them before we took off. New oil was there after we landed so they aren't loose. I'll have the local mechanic take a look at the seal on the bottom the cylinder.