Milky Oil 20 HP Mercury

I bought a older 20 HP mercury engine(1976). I then discovered the lower end had no oil. I serviced with oil and ran (water muffs) to find the oil milky after a short run. I then changed the water pump and ran it with water muffs and but the oil still goes milky again after running for a short time. The shaft seal by the water pump is new and seeing as how I'm using water muffs I don't see water getting in through the prop shaft seal. I'm confused and would appreciate some suggestions as to my next move. THANKS

Re: Milky Oil 20 HP Mercury

water could still be leaking down into the midsection from the cowel and you will get water around the driveshft seal

Re: Milky Oil 20 HP Mercury

Shift shaft seal could be leaking as well.

Re: Milky Oil 20 HP Mercury

Here's a question for ya. When you fit the muffs on the motor, do they cover your vent plug as well? If you didn't replace the small seal gasket on the vent and fill plug and the muffs cover one of them it could be forcing water into your LU.

Re: Milky Oil 20 HP Mercury

New seal defective or improperly installed(?) Shift seal as Silver said(?) and an oddball but very thoughtful suggestion about the vent screw! Prop seal would have to be insanely trashed for a little exhaust spatter to make its way in there. Pressure/vacuum test will tell ya. Don't have the tools and don't wanna hit the shop?--You can try my poor-man's test. Start by cleaning well around all seals including the drain & fill. In the evening or early morning while the unit still cold crack the vent screw and retighten, then put it somewhere it'll get direct sunlight. In the afternoon after it's been cooking look for any leaks and crack the screw again. If no leaks and it has pressure, now let it sit & cool and again crack the screw and listen for a hiss indicating it held a vacuum. If it passes both you need to buy (or make) the tools or take it to a shop. And flush the milk out asap so you don't make rust!

Re: Milky Oil 20 HP Mercury

Only one place to get in the water, pump seal.Check the shaft for excessive wear.Any grooving will allow this.
Profile? You might be close to someone who has a pressure tester.J