Fuel Pump Oil

That’s not normal. Sounds like a gasket or o ring leaking probably from crankcase pressure. Still able to burp normally?

Yes she "burps" very easily, after just a few turns.

Sean,

I have a 912UL on my Kitfox. The fuel pump vent has a clear drain portion with a bend at the pump and a small amount of fuel oil mix can be seen in the elbow after each flight so I changed the pump. I still see the same amount and added a collection test tube to the drain. After each flight the tube is checked and a few drops are there.

Charles

Hello Sean

The Corona pump vent was developed to capture any fuel or oil that got into the atmospheric area of the pump under the diaphragm so they could be directed away from the engine.  it is very normal to see a few drops of oil but it should not be enough that it is dripping.  If you feel it is excessive I would suggest you do a crankcase pressure check of the engine.  (installation manual shows it) The only way oil can get to that area is from pressure within the gearbox pushing past the O-ring or seal on the pump shaft in the pump.  If you have high crankcase pressure this will push oil past the shaft seal into that area.  

Cheers

I attached a published paper from EAA done by Brian Carpenter that has a very good description of the pump and what leaks.  It has been shown on a few of the Rotax owner threads on pumps over the years. 

Thanks Guys,

I am reassured that a small amount of oil is normal and does not indicate the failure of the Garlock seal.

I guess "small" is subjective - I catch what comes out of the breather tube, so have a way of checking for oil/fuel and any increase in leakage. 

My "catch can" is a recycled kids "Pop" drink bottle, is transparent, for ease of checking, can be had for the price of a child's drink. They appear to be hydrocarbon resistant and the top can be modified to allow for a snug fitting tube. Be sure to drill a large number of small vent holes around the neck. They come in diffrent sizes & shapes - choose one that fits your purpose. Secure to any convenient structure in the engine bay.