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Evenrude 25 hp Overheating Question

J

Joey Trufan

New member
:mad:'97 25hp overheating, pisses cold water but engine still gets hot, discharges scalding hot water upon killing engine. Tried new impeller and new stat. Thanks for any input.
 
ive been mixing the fuel myself, the impeller wasnt too bad coming out, i seem to have plenty of water flow, i changed the impeller and stat after i got hot on me the first time then it ran great for one trip (about 2 hours of run time) then went on another trip the next day and it started running hot again, but the only thing i cant figure out is why the discharge will be cold while running and as soon as i kill the engine i get near boiling water out of the discharge
 
when you kill the engine then any water that is still coming out is not flowing under pressure from the water pump and is trapped in the water jacket for a longer time......the engine heat transfer is greater...when you restart the engine does the water go back to normal discharge temp?when the motor is running can you put a finger on the motor without burning it?you may have a problem and you may not...
 
while running im not able to touch the motor without burning my hand, and if i start the engine the discharge goes back to cold but the engine will piss cold and still get so hot that you can smell it, like that paint burning smell, all while pumping cold water
 
are you really getting water just from the phole only and not through the engine?are you feeling the hot water out of the exhaust or the phole?evinrude put most of their pholes before the water jacket back then....so that water is actually straight off the pump and has not been circulated through the water jacket.....if you are getting water thru the engine i think i would back off the water problem for a few minutes and start by checking compression ......that top piston may be running hot in a 3 cylinder....
 
the hot water comes from the phole once the engine gets killed, but the phole water being before the water jacket makes sense on why it pisses cold while running and the engine is still getting hot
 
What happens when you run it without the thermostat ???-------I have 3 of these motors, the white Johnson version.
 
Salt water motor ???----------------How long have you owned it ??-------------Factory replacement impeller or aftermarket ??
 
No head gasket ( sealed with O-rings ) on that motor !!------No cover on the head.------No exhaust outer cover either.
 
Remove the gear case, thread in a nipple and attach a water hose.Slowly open the water, start the engine and increase water flow and check temp. This will tell you if it it a capacity problem or even a blockage creating your problem.
 
I had the same problem last with my 1997 Johnson 25hp 2 stroke 3 cyl. Pee'd good, but after a few moments would go to slow mode (overheating). Mine was a bad thermostat, put a new thermostat assy in it and problem went away. But, you said yours still gets hot with no thermostat in it.
 
Remove thermostatcover, spring and thermostat and run the engine in the water. Is water coming out of the thermostat location? If not, remove powerhead and cilinderhead, clean the whole water passages rigiously.
 
I have a 1997 Johnson 25 hp 3 cylinder overheats with thermostat in and runs great with it out.I have replaced water pump,thermostat twice and no luck still can’t run with thermostat in it temp sensor replaced also … fresh water motor and water flow seems great
 
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