1984 70 hp Evinrude black oil leaking out of the exhaust

[JohnT 1124]

So I was out to the lake over the weekend . We was fishing and tubing on Saturday , everything was fine we put the boat back on the trailer to come back to the camp site . Sunday morning head out to fish put the boat back in the water , idle out to the end of the no wake zone . the motor would never open up it sounded like it was running on two cylinders . So I stop and changed all 3 plugs , thought maybe I fouled one . Still the same . Turned around idle back to marina loaded boat back on the trailer and noticed a black oil leaking out of the exhaust hub , check the carbs for water , fuel lines , fuel pump was good , I just replaced all 3 coils , and fuel pump , rebuilt the carbs , new reeds , and gaskets and fuel lines , retimed the motor and carb timing . and it had been running good all summer . Took home checked compression top cylinder was 132# middle was 135# and the bottom was 119# , so whats your thoughts ? Any ideas ?

 

[F_R]

Re: 1984 70 hp Evinrude black oil leaking out of the exhaust

Gotta wonder what happened to #3, right? Presumably, it isn't firing and the fuel that went through it is running out the exhaust.

 

[JohnT 1124]

Re: 1984 70 hp Evinrude black oil leaking out of the exhaust

Thats what I'm thinking , I'm going to pull the head off and take a peak inside , it would cost me a couple gaskets and time . I was wondering could the power pack be break down ? I think with 13lb drop in the bottom cylinder it's a bad head gasket or with all the unburnt fuel is washing the cylinder walls down dropping the pressure down .

 

[JohnT 1124]

Re: 1984 70 hp Evinrude black oil leaking out of the exhaust

Took head off today and really didn't see why I'm my compression is dropping off 13lb to 15lbs . Unless it's a got a small crack some place . Does anybody have any other thoughts ?