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1987 225hp johnson temperature

G

gradywhiteman

Contributing Member
How long should it take for this engine to reach operating temp? I checked the water pump stream today with my hand after about 12 min. of idling at about 1800 rpm,s and the water was cool to the touch is this normal or could the thermostats be stuck open? Thanks
 
Re: 1987 225 johnson temperature

Thermostats easy to check for a stuck open condition. Cold engine, remove the thermostats and observe.
 
Re: 1987 225 johnson temperature

Joe, I don't have a manual yet for the engine to show thermostat locations, could you describe where they are?
 
Re: 1987 225 johnson temperature

look on the rear toward the top of your motor. at the top of each head is a square plate with rubber hoses coming out of it. there is a thermostat under each plate. they have what is called a vernatherm. A plastic housing with the thermostat inside it. gently screw the housing apart, watch out for any loose parts & the small pins in the ends of the thermostat. ck if pins are extended out of therm. one of mine was once. I used scotch brite to clean the pins, then light oiled them,worked them in & out a litlle, wiped clean, & rechecked them in water on cooktop. observe pins as the water heats, they should extend out as the temp rises.
 
Re: 1987 225 johnson temperature

On this engine not only the thermostats to check, but the pressure system that controls the by-pass.
On the throttle arm where you attach the cable is a valve in center that directs water pressure to keep the thermostats closed at lower rpm.
As throttle is advanced, the valve closes and less pressure at the back of the thermostats.
Weak pump, dirt in the valve may disrupt this system.
Pull the hoses going to the thermostat covers and check the function of the system.
If impeller is 5 years or more, just change it out.
 
Thanks for your replys. If I pull the hoses off and run it at an idle what kind of pressure should I see? Also how long should I run it with the hoses off?
 
It should be pressure almost at the same time the engine starts to 'pee'.
At low idle quite strong. No specs known as far as I know, but the pressure has to e more than the pressure on the inside of the thermostat.
Pull the thermostat covers and start the engine.
The pressure in the covers should be before water starts pouring out of the thermostat holes.
 
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