55773d exhaust cover/gasket leak

[dirtleg]

Hello fellow johnsonrude's..I have a 1977 55hp evinrude 55773d. I have had this motor for about 3 years now and I love it! It doesn't push my pontoon quite as fast as I would like but I love the engine and can't bring myself to replace it. it has in the last couple of outings been really hard to start, and when started must be sped up slowly. once moving good it runs strong except at the top end where it will run then lag, run the lag...the lag jumps in for a few secs and jumps out, if you have run your fuel tank dry and as those last drops in the tank rock back and forth across the intake and the engine surges then slows...that's the feeling just not as pronounced. My boat mechanic is a great guy...and a good mechanic and he and my research have led me to believe that my inner exhaust gasket cover is leaking and allowing moisture into the cylinders...either from corrosion, a gasket leak, or the cover itself is warped which I have read is not unusual on a 70's rude.

At this moment my first question is, do I have to lift the powerhead to remove the exhaust covers. logic tells me I do because the bottom bolts are so low in the lower motor cover that I don't think there is room for them to come out, but I am hoping there is a way to drop the lower motor cover down the shaft instead...my mechanic tells me that some good ole boys will drill holes in the lower motor cover and pull the bolts straight thru the cover to save on labor and then plug the holes in someway when done....I really don't want to do that but I really don't want to fight the powerhead or pay my mechanic the labor to fight the power head. Is there a better trick? thanks for reading and Float on!

 

[Daviet]

Re: 55773d exhaust cover/gasket leak

Have you tried pumping the primer bulb when this is happening, it will bypass the fuel pump, you might have a fuel pump going out.
Have you checked the high speed orifices in the carbs, a plugged or restricted orifice will cause the problem you are having.

 

[dirtleg]

Re: 55773d exhaust cover/gasket leak

the carbs would explain some, but do you think that would cause the water in the cylinders?

 

[Daviet]

Re: 55773d exhaust cover/gasket leak

By reading your post, you don't know for sure that you have water in your cylinders.
If it runs strong until you hit top end I would question water in the cylinders.
I would do some easy checks before I tore it down.

 

[dirtleg]

Re: 55773d exhaust cover/gasket leak

I'm sorry Daviet you are correct my original post is a bit cryptic...my mechanic told me when he did his checks that there is water droplets on the plugs when he pulled them. He had the boat in the shop and went through the fuel system, I picked it back up and used it over the holiday and now I am trying to figure the best way to address the problem

 

[dirtleg]

Re: 55773d exhaust cover/gasket leak

The motor behaves in this way.....

it will fire and crank and shut off
then it won't crank for several attempts with the warm up lever in any position
then it will fitfully crank but when shifted into gear shut off
then it will crank, and warm up but with the warm up lever lifted it will sound as though it is dropping a cylinder
then if I lower the lever and gingerly shift it into gear it will slowly accelerate as I throttle up a little bit at a time
once up and running it does fine at 1/4 all the way through 3/4 power but at the top end it isn't happy

 

[Daviet]

Re: 55773d exhaust cover/gasket leak

Have you run a compression test, maybe you have a leaking head gasket?

 

[dirtleg]

Re: 55773d exhaust cover/gasket leak

both were perfect