Oil Leaking from Pitot Tube Inlet on Gear Case

[Tacky79]

Q1: what would cause oil to leak from the speedometer pitot tube 0.25-inch diameter inlet on the leading edge of the gear case of 2017 Mercury 150-HP FOURSTROKE engine?

[jimh]

When the engine is operating and creating forward propulsion, water will be forced into the pitot tube. If the outlet of the pitot tube—usually a hose connection—is not sealed or is not connected to the pressure input port of a speedometer gauge, then the water is pushed upward and will be spilling out somewhere; from there the water is going wherever gravity takes it, perhaps collecting somewhere higher in the midsection or cowling pan. There the water mixes with grease or oil. Later it flows somewhere else—perhaps when the engine is tilted up—and then flows by gravity back down the pitot tube path and out the inlet on the gear case.

Q2: is the pitot tube outlet connected to a speedometer or sealed with a cap?

If not, find the outlet hose and install a cap on it.