Logo
FULL SITE MENU

overheating

H

honcho1

New member
Have a 72 Johnson 25hp,replaced water pump and thermostat,still getting hot,removed new thermostat and still getting hot. I have worked on many OMC engines but never ran across this problem. What else could it be? Thanks:cool:
 
kevinj said:
I'd suspect this too. It's time to remove the head and exhaust plate to start looking for debris that is blocking water passages.
Click to expand...
The pisser is real strong,just had the head off to replace plug at bottom of head. I am thinking the water passages are clogged,where do I start and what do I do? Thanks again Todd:cool:
 
So take the exhaust plate off and look to see if I have blockage?? I can't think of anything else it could be,I guess the water passages are behind the plate?? Thanks again,this is kicking my tush
 
72 doesn't have a pisser all water comes out the exhaust relief did you add one whee exactly is the water coming out. You can also try this take the thermostat housing off and start the motor. See if the water flies out.
 
yea sorry thought you were talking about the exhaust,but the water comes out strong,if no water comes out of thermo housing,what's next? Thanks again
 
There is a part number 313435 plastic water restrictor in the exhaust housing, below the powerhead. It melts if the motor runs hot (and you say it does). So, lets begin with that. Pull the powerhead and check it.

Next, you have to understand how the system works. There are two water flow paths through the powerhead on that motor. Only one path is controlled by the thermostat. However, as the 'stat opens and closes it indirectly affects the non-controlled side.

So...you are going to pull the powerhead for the restrictor. While you have it off, pull the exhaust cover off the side and look for obstructions, remembering there are two flow paths.

BTW, marineengine lists the 313435 restrictor as unavailable. You may have to do some searching. Good luck.
 
It could be the water circuit going out of the head. Get a gallon of salt away and run it in a barrel of water for about half an hour. Just keep monitoring the head temp if it gets too hot to hold your hand on shut it down. That is why it is important to flush a motor after each use even lake water has alot of minerals and silt that can build up over time. The saltaway will dissolve the corrosion and flush the crap out. I would try that first before pulling the powerhead. You should get a spray of hot water out the exhaust relief when the thermostat open up.
 
I am thinking pull the exhbaust cover first??? It will be the easiest,but what most commonly occures in this situation? Before I dive into this, I wanna get all knowledge I can. Yea Kim,,really man I understand running salt thru system,but gotta fill a garbage can full of water to do it,that's alot of salt ,which is no big deal, but would only be able to run it for a limited time till it gets hot, this is a strong motor and I will not let it die,just gotta figure wtf is going on here,thanks again:cool:
 
No your misunderstanding the salt-away will dissolve any salt and corrosion you will almost know immediately if it works because the wil start running at normal temp. Start it and monitor the head temp with your hand. If you cannot hold your hand on the head for a slow count to six shut it down. it only takes a few minutes to reach normal temps.
 
Ok,where can I get this salt-away? I really wanna try that first before I go tearing into the powerhead thanks Kim for the info man
 
Yea i ran CLR and vinegar thru it today and it's still getting hot,you think maybe if I took the exhaust plate off,it may be clogged there? I know I will have to get new gaskets,but beats taking powerhead off. Man this is kickin my butt
 
Back
Top