1999 25hp Johnson overheating

[Colby4bush]

im sure you get this all the time but this is different, I’m getting water out the back but no water is pumping past the thermostat so we changed that! Still nothing, it don’t seem like any waters making it to the thermostat, can there be a plug somewhere? It seems like it’s shooting out and unusual amount of water in the back, usually it’s just a stream but this stream is pretty big! Am I missing something here? Is the impelller working but not good enough?

 

[fireman57]

Are you sure you got the water tube properly seated at the top? I believe there is an oring that goes up there too.

 

[oldboat1]

Sure the motor is overheating (somewhere around 160F at the top of the head)?

If you don't think water is getting to the t.stat, try removing the l.u. and manually pushing water up the tube. Might remove the t.stat for this and see if water is getting up there. You should be testing the system in a barrel (water a few inches above the pump), or in the lake. Running on muffs doesn't adequately test the water pump.

 

[scout-j-m]

Sure the motor is overheating (somewhere around 160F at the top of the head)?

If you don't think water is getting to the t.stat, try removing the l.u. and manually pushing water up the tube. Might remove the t.stat for this and see if water is getting up there. You should be testing the system in a barrel (water a few inches above the pump), or in the lake. Running on muffs doesn't adequately test the water pump.

You can adapt a regular garden hose to a piece of spare smaller diameter hose that's been cut off and secure it to the water tube with a good hose clamp. This will allow you to force water through the cooling passages without running the motor. Remove the thermostat and leave the cover off to see if water is making it to it first. Then leave the tstat out and replace the cover and see if you notice a difference in how the water is ejecting from the various locations. I'm not sure what water pressure a typical 25hp motor produces but you could also adapt a pressure gauge on the hose adapter to make sure you don't apply too much. I would guess and say 20 psi is about the max you would normally want to go but a little more may force out some kind of clogging debris? May also want to run the motor in a barrel and add Dawn dishsoap to the water....I doubt it really helps but Iv'e done it in the past just in case it may help clean the water passages.

 

[flyingscott]

Is the pee hole running good? How do you know there is no water in the thermostat? You should have a healthy stream running out of the 2 holes. More than likely if the pee hole is running your tube is connected properly. Take the thermo cover off and remove the thermostat. Now put the muffs on and start the.motor. Water should come.out.