1985 20HP Johnson Water in Cyls, Carb flooding.

We have a 1985 20HP Johnson model J20CRCOS outboard with a manual primer. The problem were having is the lower cyl is taking in water. The motor will run until it starts pumping water then promptly shut down. When we pull the plugs the upper cyl is flooded with fuel and the lower is mostly dry with water droplets on it. The carb also has fuel pouring out of it. Not from the bowl vent. The carb has been rebuilt with a new needle, seat and gaskets. We also adjusted the float as specified by the instructions in the sierra rebuild kit.

Where do we start? I'm leaning towards blown head gasket, but this is nothing like a chevy 350. It has compression and runs smooth and on both cyls until it starts pumping water. Then slowly boggs, shuts down and will not restart until we blow out the plugs, cyls and dry the carb.

Re: 1985 20HP Johnson Water in Cyls, Carb flooding.

I suspect it is a blown head gasket letting water into the cylinder. There could be other problems causing the water intrusion, but the head gasket would be a good place to start. The fuel pouring out of the carb indicates a stuck float. Hope this helps

Re: 1985 20HP Johnson Water in Cyls, Carb flooding.

Thanks for the quick reply. I was wondering if the coolant/water entered that part of the engine. I thought it may only cool the cyl walls and never actually enter the head...

I noticed that theres a line 1/16" line that goes from the primer to the bottom of the block. Could there be a chance that the fuel is coming from the passages inside the block and flooding both the upper cyl and the carb? The float seems to work fine. We pulled the carb off more than 5 times to check it thinking the float was sticking. Its free inside, and can hear it moving if you shake the carb. Could there be a chance the fuel pump is providing too much pressure and over filling the bowl in the carb? If we prime the primer bulb I noticed fuel coming from the brass tube in the center of the carb. If you prime the bulb one more time fuel will exit the bowl vent...

Re: 1985 20HP Johnson Water in Cyls, Carb flooding.

Did you change the float valve seat and gasket when you had the carb apart?

Re: 1985 20HP Johnson Water in Cyls, Carb flooding.

The water will circulate through the head when the thermostat opens. And water can get into the cylinders because of a faulty gasket.

I am suspecting that the new carb kit you put in has a thicker gasket under the float needle seat. I had that problem with a sierra kit before. If you still have your old parts, compare them with the new parts. The float level should be exactly parallel with the carb body when the float is closed and the carborator is upside down.

Re: 1985 20HP Johnson Water in Cyls, Carb flooding.

If it's not the head gasket where the water is coming in the cyl it could be the exhaust cover gaskets or a burned out exhaust plate.

Re: 1985 20HP Johnson Water in Cyls, Carb flooding.

oldcatamount said:

Did you change the float valve seat and gasket when you had the carb apart?

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Yes I changed the seat, the gasket and the needle that attaches to the float.

Cofe said:

The water will circulate through the head when the thermostat opens. And water can get into the cylinders because of a faulty gasket.

I am suspecting that the new carb kit you put in has a thicker gasket under the float needle seat. I had that problem with a sierra kit before. If you still have your old parts, compare them with the new parts. The float level should be exactly parallel with the carb body when the float is closed and the carborator is upside down.

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The parts look Identical except the new float valve has a rubber tip and the original is all metal. I adjusted the float to sit level with the carb upside down. Then adjusted the little tab to make the distance from the float to the carb 3/4".

boobie said:

If it's not the head gasket where the water is coming in the cyl it could be the exhaust cover gaskets or a burned out exhaust plate.

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That sounds viable. When we used compressed air to dry the cyls out I noticed the lower unit would blow bubbles. It only bubbled when we blew into the bottom cyl. Which is the one that is getting water.

Re: 1985 20HP Johnson Water in Cyls, Carb flooding.

If the head gasket is bad between the botom cylinder and the water jacket. Blowing air into the lower cylinder will also cause the lower unit to bubble.

Re: 1985 20HP Johnson Water in Cyls, Carb flooding.

Well looks like the only thing to do is pull it apart and see whats wrong.