Johnson 15hp no water coming out - blown head gasket?

[eminyan]

No water is coming out from the cooling system of a Johnson 15hp I just bought. I checked the water pump impeller and it seems OK. Compression seems to be leaking into the cooling sytem as fumes are coming out of the water outlet tube on cranking the engine. It also suddenly got difficult to start. It seems all the symtoms of a blown head gasket. What do you think? <br />Thanks and regards<br />Maurice

 

[ajohnston]

Re: Johnson 15hp no water coming out - blown head gasket?

pull plugs and check for water on the plugs one or more if water present sure sign of blown head gasket

 

[clanton]

Re: Johnson 15hp no water coming out - blown head gasket?

Model, serial number, or year. If it is a 80s model remove the thermostat housing, start engine, should pump a lot of water. If not a lot of water, the upper water tube grommet has swelled and blocked the water tube.

 

[eminyan]

Re: Johnson 15hp no water coming out - blown head gasket?

Thanks for your comments. There is no sign of water on the plugs. When I took the lower unit off and poured water though the thermostat housing water came out freely from the tube that goes into the pump and out of the outlet tube on the powerhead. What's making me think I've got a blown gasket also, is the fact that exhaust fumes are being pumped out of the water outlet tube on cranking.<br />Regards<br />Maurice

 

[Hooty]

Re: Johnson 15hp no water coming out - blown head gasket?

I'm not sure if I understand your posting or not maurice, but if I do, the water and exhaust are suppose to come out together.<br /><br />c/6<br /><br />Hooty

 

[sho305]

Re: Johnson 15hp no water coming out - blown head gasket?

I have had many motors not pull water well after sitting dry. Had to put deep in water as on a boat or use earmuffs to get water going fast enough to feel safe. Then it was OK. I like to force the water up there with earmuffs first, then try it in water. Sticking it in a tub of water up to the prop seems to not work well on a dry motor.<br /><br />Make sure the pee hole is not plugged too.<br /><br />Does it have a flush plug? Maybe plugged up w/ dirt?

 

[jgmilberg]

Re: Johnson 15hp no water coming out - blown head gasket?

Just a thought, but did you notice if the water pump impeller has it's keyway installed? If not the impeller will not spin. Also make sure that the tube from the top part of the motor is inserted into the water pump housing correctly.

 

[Boatist]

Re: Johnson 15hp no water coming out - blown head gasket?

If it is a early version of Johnson's 15 HP then no water is normal. No water comes out until the thermostat opens. Even then just a light spray and if you are running it out of the water all the water will exit out the lower water outlet above the cavitation plate. Later models with the pee hole should have water at the pee hole but still no water at upper water outlet until thermostat opens. Out of the water still exits at lower water outlet. If your model has the pee hole and no water is coming out I would check the water pump drive key in the water pump.

 

[eminyan]

Re: Johnson 15hp no water coming out - blown head gasket?

Thank you all for your comments.<br />Hooty - the exhaust fumes are actually coming out of the pee hole. If I blow through the pee hole pipe you can see fumes coming out of the spark plug hole. It wasn't very reassuring when I discovered that!<br />Sho305- The problem is that there is no space to put on earmuffs. It did pull up water for a while after I immersed it in a deep tank. Pee hole is definetly not plugged. I didn't check the impeller key though.<br />Boatist- Another problem is that I can't figure out the year of this motor. I've looked everywhere,transom plate, engine block, I've only got the serial no. The guy I got it from said it was a 1992 but I wasn't able to confirm that yet.<br />Regards to all Maurice