Oil cap removed

On my older Kitfox (with a pretty high mounted oil tank), I need to turn my prop for quite awhile (don't remember the turns...I should remember them), before I hear the "gurgle".  I understand it is necessary to go through this procedure at least the first flight of the day, to make sure all the oil in the engine is (pushed) back up to the tank.  For two really good reasons I can think of, to check for possible hydraulic lock in the cylinders, and to get an accurate dipstick measurement of the oil amount in the system.  I know with the varying levels of oil tank mounts, the physics of each individual system are likely not all the same.

Skot

Hi Gaston

If you are new to Rotax aircraft dry sump operations it may be you are simply not doing enough rotations.  The turning, in the correct direction, should be slow and push gently past compression on each piston TDC.  It may take 6 to 20 turns to get to hear the sound of air mixed with the oil return.   if you are not hearing it push the mixed air and oil into the tank, the glu,glu, glu as you call it, then you have not cleared the return line from the engine to the oil tank of the solid column of oil.  

https://www.google.com/search?q=how+to+burp+your+rotax&oq=how+to+burp+your+rotax&gs_lcrp=EgZjaHJvbWUyBggAEEUYOdIBCDY1NzVqMGo3qAIAsAIA&sourceid=chrome&ie=UTF-8#kpvalbx=_n4dDZsbjFu7v0PEPwpClsAg_32

Cheers

Technique may help speed the process- I pause, for a few moments, after each max compression.

The idea being that, some of the compressed air, from the combustion chamber, will leak past the rings, into the crankcase, speeding the crankcase pressure rise.

My oil tank, mounted within Rotax specified height, usually "Gurgles" after 1.5 - 3 full propeller rotations.

Hi Skot,

Think of each engine as its own personality. Some will gurgle after 3-4 turns and some take maybe 20 turns. The more turns just means you  have more oil in the bottom of the crankcase to push back to the oil tank with the air from the engine as you rotate the prop. It makes no difference how many turns, you just do it and like you said it rules out hydra-lock.