Possible Water Obstruction in Cooling System?

[Jon Boat Jim]

The pee stream on my 1990 25 HP Johnson all of a sudden stopped. I thought that it might have picked up some debri and that I have something clogging the cooling system. I blew air into the pee hole and I get plenty of bubbles from the water pickup ports. Does this prove that that is no blockage?
Is there some sort of "back-flush" method to force air or water through the cooling system (top/down) to check for or dislodge any debri?

 

[oldcatamount]

Re: Possible Water Obstruction in Cooling System?

Take off the lower unit and look at the impeller. When you have the lower unit off, hook up a garden hose to the copper pipe that feeds water up to the motor. Remove the thermo-stat cover and blow water up the pipe and thru the motor with the hose. If the impeller is missing a vane, that could be your problem.

 

[Jon Boat Jim]

Re: Possible Water Obstruction in Cooling System?

I was hoping that there would be some way to flush without taking the lower unit off. What about pumping water with a small hand transfer pump attached to the pee hole (rubber hose) or to the thermostat? I could also remove the thermostat and check for blockage.
I'm trying to eliminate "blockage" as the problem before I get into the lower unit and replace the impeller.

 

[dew2]

Re: Possible Water Obstruction in Cooling System?

If you back flush it any particals will end up in the water pump housing anyway,Just drop the lower and flush as stated above.

 

[Jon Boat Jim]

Re: Possible Water Obstruction in Cooling System?

An update: I was able to clear the debris from the engine using a "Multi-Use Transfer Pump" (Harbor Freight Item 66418) to back-flush thru the pee hole line. I was able to slip the outlet hose over the pee hose from the engine. I pumped (back-flushed) clean water through the cooling system. After a while, I started the engine and had a trickle out the pee hole. I repeated the process several times....back-flush, start engine, repeat until I had a strong steady stream.
This process saved me from removing the lower unit and perhaps from removing the thermostat.

 

[j.b.b.]

Re: Possible Water Obstruction in Cooling System?

hi i have a 1957 johnson javelin. Just put in a new impellor but still no water coming out with the exhaust. should i also try hooking up a gardne hose to the copper water pipe pick up from the pump?