Universal M25 Oil Leak

[Russ Williams]

I have a 1984 C36 with the M25 Universal engine. I have a small amount of engine oil that slowly leaks from what looks like a small breather cap/port on the rear portion of the fuel injection pump. The leak seems to get worse with increased RPM's. Over an hour or two it's enough to drip down the side of the engine and into the engine pan causing a small mess. Any ideas on what is causing this??Thanks,Russ

 

[Rob Sherrill]

Oil Leak

I had almost exactly the same thing on my Yanmar Diesel on my Hunter Vision 32. It turned out that there is an external oil line on the back side under the anti-syphone system. Over the years the "dripping" caused corrosion and cause the line to get a pinhole leak in it. Had the line replaced and works fine.Check to see if you have an external line that has been tie-wrapped with some other cables. Mine had causing all the water to drain to the mid-point and set which led to the corrosion. Of course it didn't appear before I bought the boat because the boat had been used very little. When I started sailing it at least twice a week the engine "shaking" worked loose the hole.Hope this helps.

 

[Gordon Torresen]

The leak you describe is coming from a stop mechanism adjusting screw. The stack up is: the adjusting screw, a sealing washer, a lock nut, another sealing washer, a cap nut and a cover.it sounds as if something has come loose. What you do, if you are willing to undertake the task, is pry off the round cover. It was installed by putting it over the cap nut and then staking it slightly. When this is off, try tightening the cap nut. If it moves at all, you have probably stopped the leak. Try running again before reinstalling the cover cap. If the leak is stopped, reinstall the cap at your convenience. If the leak continues, you will most likely have to replace the two sealing washers. You should try not to change the adjustment of the screw. The screw can be held in position by a screwdriver slot in its end. When breaking free the cap nut, have a wrench on the lock nur to keep the whole shebang from coming out.

 

[Russ Williams]

Gordon-Thanks for your insight. Your description de-mysifies the entire thing for me. The way the cap was staked but would turn slightly led me to believe this was some sort of "breather" or vent. It make sense now and I'm relieved that it will be a simple repair and will solve a nagging problem. I guess I should purchase the repair manual - It probably would have shown this arrangement!Thanks again,RussC36 #206Four Sail