The International Cessna 170 Association

Hi All
Where should my crankcase tube terminate?
Mine is about 2 inches above the bottom lip of the cowl. The cowl has a 1.5 inch lip.
Does this sound right?
Mine drips a yellow goo when shut down.

Dick Bryant
54 170B N2704C
26248

It is common to terminate the vent above the lip of the cowl to keep the vent in warm air to prevent the end freezing and plugging off the vent. There should be another hole in the vent tube somewhere 6” or more above the end of the vent to act as a pressure relief in case the end of the vent does freeze and plug off.

There is always water vapor and oil vapor exiting the vent while the engine is running. When you shut down, the residual water and oil vapor left in the vent will drip out, that is the yellow goo. Each plane will have more or less dripping depending on how much vapor the engine produces.

Some folks remove the oil filler cap after they shut down to allow the crankcase to vent some of the oil and water vapor still retained in the hot engine. With the oil filler cap removed and left off until the next flight fresh air can circulate thru the case possibly helping to reduce condensation corrosion. Without removing the oil filler cap, the engine is closed up and traps the condensation inside the engine. Removing the cap should not ever cause a problem because we all check the oil before starting the engine, correct?

Thanks
I do remove the oil cap and give it a shake to get rid of the condensate after shut down.

Dick