Mercury 75HP 2 Stroke Oil Leak

[markjuk]

Hi, I have a 2003 2 Stroke Mercury 75HP. Ever since I bought it I have had problems with the 2 stroke oil resevoir leaking from the cap. I have tried ensuring that the o-ring and the top of the tank are free from oil and using a new o-ring but it still leaks when the engine is raised. Any tips on how to stop it?

 

[lncoop]

Re: Mercury 75HP 2 Stroke Oil Leak

How high are you raising it? I have the same design on my '02 90, but it only leaks when the motor's tilted way up.

 

[ufm82]

Re: Mercury 75HP 2 Stroke Oil Leak

Is the cap cracked? My 150 leaked under the cowling and I looked everywhere for the leak to no avail. I took that cap off several times and it seemed fine- I never saw a crack. However, I finally got frustrated and bought a new cap just to say I did. I put the cap on and the leak stopped. Figuring the cap MUST be cracked, I put it back on the reservoir and really cranked it down- that's when the tiny crack appeared. It was only 1/2 and inch long but it was such a fine line that I couldn't tell if it was a crack or a casting line. Turns out it was a crack. $18 dollars later I was leak free.

UFM82

 

[markjuk]

Re: Mercury 75HP 2 Stroke Oil Leak

Thanks UFM82. I can't see anything wrong with the cap but maybe I should just bite the bullet and buy another one.

 

[markjuk]

Re: Mercury 75HP 2 Stroke Oil Leak

Incoop - quite high, but it needs to be quite high to bring the engine out of the water.

 

[Dave1027]

Re: Mercury 75HP 2 Stroke Oil Leak

Mine has always leaked but I'm cheap bastard so I just never fill it up so much. A full tank of gas uses less than half the oil tank any way. I simply add more oil every time I gas up.

 

[longshanks]

Re: Mercury 75HP 2 Stroke Oil Leak

I have the same motor and mine leaked around the cap when the motor was fully tilted up. I put a stop to it by tightening a stainless steel hose clamp around the outside of the reservoir and cap, which slightly constricts the clearances around the filler cap and has completely stopped the leaking. A better solution than buying a replacement tank, which is no different than the original one. I suspect that it slightly warped out of shape from sitting above a hot engine.

 

[markjuk]

Re: Mercury 75HP 2 Stroke Oil Leak

What an excellent idea. Many thanks for that.