1996 Johnson 50 hp no compression in lower cylinder

[bkruger]

The subject says it all. Bought used boat 2 weeks ago that had been sitting unused for 6 months in the water. Have only ran motor about 1 hour and it ran rough, but replaced old gas and it seemed to smooth out. Noticed yesterday that I wasn't getting the power I had the day before and also had an audible alarm go off so I immediately shut off motor. I pulled the carbs and cleaned them, still nothing. Found hardly any compression in lower cylinder. Still runs on top cylinder just fine. Local boat mechanic says that I need a complete rebuild. Anyone here have some thoughts on this? BTW, I have no idea what the alarm meant. The water pump is working fine it appears that the oil pump is working (seperate oil tank).<br /><br />Thanks

 

[R.Johnson]

Re: 1996 Johnson 50 hp no compression in lower cylinder

The only way you are going to know what you have is to pull the cylinder head. Anything else is just a quess. Could be just a head gasket.

 

[Solittle]

Re: 1996 Johnson 50 hp no compression in lower cylinder

Before you pull the head do a decarb on the motor followed by a compression test. You may just have a stuck piston ring.

 

[bkruger]

Re: 1996 Johnson 50 hp no compression in lower cylinder

How do you decarb? The stuck piston ring was my first thought. I've rebuilt many a small engine, but first time on an outboard. Just a guess on the compression right now, but I'd say between 5-10 lbs. at the moment. I'd really like to try this decarb first. Any help?<br /><br />Thanks.

 

[R.Johnson]

Re: 1996 Johnson 50 hp no compression in lower cylinder

Decarb is not going to bring a cyl. back with that low of compression.Pull the head then you know.