Is my Johnson finally dead?

[bellboy120]

I have a 1977 Johnson 35 hp motor. This motor has been used in salt water for at last 5 years that I know of. Last weekend took the boat out. It started up just fine and we were leaving the harbor, but the motor was running at half speed at full throttle. After about 5 minutes it sped up to full throttle speed, then slowed down, then spend up. While in transit it then died. Started it again and it died again. Checked gas lines vents all that jazz. I continued to try and start it with no luck. Then it did fire up and ran for about 2 minutes and died. <br /><br />Later that day I pulled the carb off and cleaned it will air pressure (had it rebuilt last year). While in the driveway it wants to run for a few seconds but dies. During the repair process I had the plugs out and notice water mist was coming out of the top cylinder? How could that be. The motor never got hot and water was flowing through the pisser hole. I rebuilt the head a couple years ago. It was the first time I ran the boat since last season. The compression is 50lbs for both cylinders. I’m trying to take the flywheel off for inspection to see if timing is off or something of that nature.

 

[fixdamote]

Re: Is my Johnson finally dead?

make sure you got an even gas flow, and its clean.<br /><br />also check for any grounding, or fouling out.<br />also air intake. or bad gas line.<br /><br />you'll figure it out. just takes time...<br />

 

[joaklay]

Re: Is my Johnson finally dead?

50 lbs of compression is bad. Remove the cyl head and see if the gasket is NG to begin with.

 

[tashasdaddy]

Re: Is my Johnson finally dead?

could be head gasket, exhaust gasket. was it winterized this last year?

 

[Ranger01]

Re: Is my Johnson finally dead?

While i dont know a great deal about your particular motor, i know that 50 lbs isnt a good number for compression, Not that i have ever heard anyway. i think that joaklay and tashasdaddy are on the right path with the head gasket/cyl head suggestion.

 

[bellboy120]

Re: Is my Johnson finally dead?

Thanks for the advice guys. What should the compression be? I could not find the compression info in my manual. I've never winterized it before. I'll usually try and let it run once a month for 15-30 min during the off season. The head gasket won't be a problem to check, but the exhaust gasket will be problematic. More than likely I will snap some bolts trying get them off. There a very rusted and corroded nightmare. Any other ways of checking that the exhaust gasket it is blown? I'll turn a wrench this weekend let you all now what I find. Thanks agin.

 

[Solittle]

Re: Is my Johnson finally dead?

I would try a different compression gage before heading to the dump. Are you sure that what you saw was water mist and not fuel? If water pull the head & have a look see. If not my guess is that all you need is a carb rebuild - blowing it out with air won't cut it and having it rebuilt a year ago doesn't mean much now.

 

[BoatBuoy]

Re: Is my Johnson finally dead?

I have a '77 35 hp and it pumps about 140-145lb. of compression (elec. start).

 

[marinemech1]

Re: Is my Johnson finally dead?

compression spec is not published in older omc manuals for a good reason as oil film will mask compression results<br />remove head and inspect gasket top of piston and cylinder wall<br />that should tell you whats wrong