cooling system 1987 Johnson 90 hp

[CED8ED]

I just bought a 90 hp Johnson (1987). Just ran it on the muffs for the first time today and it seems I have a cooling problem. One bank of cylinders (one side of the V) seems hot, so hot you can't keep your hand on it and the other bank is OK. Pee stream is strong. Is this a thermostat problem? Are there 2? Where are they located? Any help would be appreciated. Thanks in advance.

 

[tashasdaddy]

Re: cooling system 1987 Johnson 90 hp

you have a bubble back 90. the tstats are on the back under the bubble, extremely hard to get to, also the motor has rubber water deflectors, that could be bad.

you need an OEM Johnson manual, outboardbooks.com or searayman13 on ebay.

 

[emdsapmgr]

Re: cooling system 1987 Johnson 90 hp

The telltale indicates the pump is working. The thermostat housing has two stats in it, each controls one side of the block. If one does not open, water cannot escape out of the block and that side of the block will heat up-even though you have a strong telltale. Have a look inside the thermostat housing, as Tas mentioned. You'll be better off if you replace both stats. Also, check the nylon pressure relief valves to be sure they are not heat deformed.

 

[kenmyfam]

Re: cooling system 1987 Johnson 90 hp

Change both stat's would be my first step with one hot bank of cylinders.

 

[CED8ED]

Re: cooling system 1987 Johnson 90 hp

Thanks to those who replied. Took the housing off (pain in the...) and both thermostats were ummm nothing left of them. Both of them appear to have erroded away, save the main part that sits in the housing. How is this possible??? As near as I can tell this motor has only ever been operated in fresh water. Anyway.... replaced the t-stats and she seems good now. Hope to get out on the water with it today.

 

[kenmyfam]

Re: cooling system 1987 Johnson 90 hp

Thanks to those who replied. Took the housing off (pain in the...) and both thermostats were ummm nothing left of them. Both of them appear to have erroded away, save the main part that sits in the housing. How is this possible??? As near as I can tell this motor has only ever been operated in fresh water. Anyway.... replaced the t-stats and she seems good now. Hope to get out on the water with it today.

Good Luck. Hope it works out for you. Be sure to post your results.