1977 johnson 85 hp javelin overheating?

ok i just recently got this motor over heating alarm is go off in control for over heating loud buzzing noise
motor is peeing just fine what else should i look for and could i be getting a false reading from the sensor
does anybody know what temp engine should be run at i have never had it out on the lake only ran it on muffs
any suggestion or thoughs would be greatly appreciated

thanks

Re: 1977 johnson 85 hp javelin overheating?

First of all, the engine can't be a 77 if you have a telltale in the lower cowling. OMC did not put telltales on their engines till 1978. You have two thermostats in that engine, each controls the temp to one head. The stats are 143 degree, the temp at which they first open. Normal operating head temps will vary between 143-153 degrees. You will get a constant overheat horn if the head temp in one/both heads gets up to 212 degrees. The horn will silence once the temp of that head goes back down to 175 degrees-still too hot for normal operation. The overheat device in each head is actually a switch. The switch will go to ground, singalling an overheat to the horn in the control box. You might rent/borrow a laser temp gun to correctly measure the actual temps at each head an see if one/both are overheating at idle. The thermostats control the water exiting the powerhead. If one stat is stuck closed the cooling water won't be able to circulate through the powerhead and you will overheat at idle. The engine can have a strong telltale, but still overheat- if the water can't circulate past a stuck closed thermostat.

Re: 1977 johnson 85 hp javelin overheating?

thanks for the reply i will start my search there with the thermostats

Re: 1977 johnson 85 hp javelin overheating?

Does a 1977 Johnson javelin motor have a weep hole