1977 85hp electric low compression on port cylinders

[leckbass]

83EL77S
J4758585

I was messing around with my old engine this afternoon and decided to put in the new plugs that have been sitting around. When I pulled out the lower Port plug, it looks pretty clean. All the rest of the plugs had a distinctive old 2-stroke look. I put the plugs back & torqued them down, then started the motor. The motor was running so I pulled off one of the plug wires and the motor slow down significantly, pretty normal... then I pulled off the lower port side plug wire and had no change.

One thing led to another and I did a compression test on the motor. Sure enough both port side cylinders were at 60 PSI and both starboard side cylinders were at 90 PSI...

The only work I did to this motor recently was removing the carburetors and changing the fuel lines. I've run about 36 gallons of fuel through this motor over the last few weekends. Never had any running issues at all.

Maybe a head gasket? Open to suggestions.

[316jughead]

Could be head gasket, between cylinders. Wouldn't hurt to pull the head and take a look, with both cylinders at 60 pounds it's very possible.

[leckbass]

I have to assume that nothing I did involving the carburetors or fuel lines would have caused this.

When removing the cylinder head, do I also have to remove the cylinder head cover and get that gasket as well? Or can I just remove the cylinder head?

[316jughead]

Just remove the head.

[ChampioNman]

If you are going to pull the head off you'll need a new gasket, so while you're in there replace the water deflectors on that side.

[leckbass]

Is that the little rubber tube that connects the two cylinders together?

I can't believe the head gasket is 50 bucks for this engine...

[ChampioNman]

You're looking in the wrong place then. Suggested retail is $27.29 Part number 0318358 www.marineengine.com has them for $19.38 each. Yes the deflectors go in the water passages of the block. # 0322411.

[leckbass]

You're looking in the wrong place then. Suggested retail is $27.29 Part number 0318358 www.marineengine.com has them for $19.38 each. Yes the deflectors go in the water passages of the block. # 0322411.

I keep coming up with part #0318662 for the head gasket

[leckbass]

Got home today and decided to give a couple squirts of oil into the plug holes and do another compression test. Compression went from 60 to 68 on both cylinders.

Seems minimal to me.

I pulled the head off... don't have a clue what I'm looking at. But it sure looks nice and clean to me.

The cylinder walls seem very smooth with a slight bit of lines at the three position on both cylinders. The head gasket looks like it's in very good condition as well.

[leckbass]

pic host

picture url

[ChampioNman]

Sorry my mistake. And I apologize. I was looking at the 115 HP you're lucky the parts are still available. My apology.

[316jughead]

To me it looks like that side has been running cold, may have some carbon build up on the rings. A good decarb might help a lot.

[leckbass]

To me it looks like that side has been running cold, may have some carbon build up on the rings. A good decarb might help a lot.

I really think the picture is deceiving, because I couldn't believe how clean it looked, very little carbon

[leckbass]

I will try to take a better picture cuz it really does not look dirty at all

[omcforever]

To me it looks like that side has been running cold, may have some carbon build up on the rings. A good decarb might help a lot.

I still have some 85 HP heads, gaskets, misc parts lying around. I unique crossflow.

[leckbass]

I don't know if these pictures show any better, but again they had was so clean, I really couldn't believe it.

[316jughead]

When a motor runs cold a problem called coking occurs at the rings. Carbon fills the rings and they begin to stick. In the mid 80's we had a terrible time with that problem, I have seen and overhauled many of these motors. I could almost do two a week and had plenty of work. It is hard to see the rings in your pictures, but I think I saw enough to think what I posted. Your oil in the cylinders test indicates that you have a ring problem. A good decarb is in order. Good luck.

[leckbass]

When a motor runs cold a problem called coking occurs at the rings. Carbon fills the rings and they begin to stick. In the mid 80's we had a terrible time with that problem, I have seen and overhauled many of these motors. I could almost do two a week and had plenty of work. It is hard to see the rings in your pictures, but I think I saw enough to think what I posted. Your oil in the cylinders test indicates that you have a ring problem. A good decarb is in order. Good luck.

I'll give it a try, what should I do?

In the end of August, I picked up two cans of Evinrude engine tuner and sprayed it down the carburetor throat and did my standard decarb. I just did this for standard maintenance.

I'm thinking I should spray it right on the cylinder Rings while the head is off and I will tilt it up.

I'll give anything a try at this point.

[leckbass]

I still have some 85 HP heads, gaskets, misc parts lying around. I unique crossflow.

If you have the head gaskets, I'll buy them off of you. Send me a message

[ChampioNman]

That was my mistake the 85 and 115 are the same block and when you get old, you forget tech bulletins. The 85 HP is NLA, but www.marineengine.com has them for the $53.00 price I'd get them while I can.