94 Johnson 90hp running hot????

[adm1476]

I have a 90hp Johnson, got her running today. After about 5 minutes of running I noticed that it was hot. Like sizzling water in the head hot. I shut it off and cooled it down with my hose. It was pumping water from the pee hole the entire time it was running. I began investigating and found that it had a broken thermostat. I had removed the thermostat housing to look for the blockage.I tried running water into the heads on both sides, and it does not come out on the other side. Is this normal? I figured it should circulate from one side to the other. I am going to remove the thermostats and reinstall the housing tomorrow and run it again to see if it gets hot again. Also why would it be peeing if the water passage was blocked?

 

[racerone]

Do a compression test first.-----You are just not aware of how water circulates in this motor.----------The factory manual has a water flow diagram.---------------A strong ( like a race horse ) pee stream does NOT mean that water is circulating properly through the block !!-------Perhaps the water diverters / guides are out of position.------------Cylinder heads need to be taken off to inspect them.

 

[adm1476]

Compression is good still, luckily. Actually I had no idea whatsoever how the water flow is through this motor. I did assume if it was peeing that the water pump was working and that water was flowing through the motor. But you didn't answer my question? Should water being put into 1 side of the motor flow through and come out on the other side? If so I have something else going on in addition to the broken thermostat.

 

[racerone]

There are 2 thermostats and water flow splits on this motor.

 

[Clyde Jones]

i have an 88 spl that had a similar problem... my suggestion would be to take the thermostats out and run it to see if it still gets hot... if it doesn't get hot it would seem you have faulty thermostats and those need replacing... if it still gets hot i would recommend taking off the heads and cleaning all the water passages the best you can... but be aware that removal of the head may result in broken/stripped bolts that may need to be repaired.

my stream was peeing strong and getting hot... i pulled off the heads (broke a bunch of bolts) , cleaned out water passages best i could, installed new deflector tubes, put on new head gaskets (cheap buy) and its running at normal operating temp now...

and from my understanding the 88spl and 90 are pretty similar

 

[racerone]

The 88 and 90 hp motors are exactly the same block !