1962 Johnson 5.5 Temp. Question

[Scott J]

First off I would like to thank the people on this site for all of the help that they have given me in the past. It has helped me tremendously getting this motor back on the water.<br /><br />I have a '62 Johnson 5.5 hp motor that hadn't been used in years. Last year I replaced the water pump and thermostat and a bunch of other stuff prior to running it for the first time. I only took it out once and it seemed to be running hot at close to WOT. I checked this by putting my hand on the head, it seemed pretty hot. I have read here that you should be able to hold your hand on the head for a few seconds. I am not sure if it is running hot or am I just being paranoid. <br /><br />I have a thermocouple that I would like to attach to the motor to check the actual temperature and leave on the motor to be safe. I read in my manual that the way to check operating temp. is using two heat sensative markers. One should change color at 125 F at idle and one should not change color at 163 F @ WOT. I am assuming that this means the motor should operate between 125-163 F ? <br /><br />I am thinking about placing the thermocouple wire under a head bolt. Has anyone had any experience with this? Is this a good idea?<br /><br />Thanks,<br /><br />Scott

 

[R.Johnson]

Re: 1962 Johnson 5.5 Temp. Question

Those temp. stik's don't change color, they melt. They will appear as chalk when rubbed on, then turn glossy as they melt. On your engine, as long as you have good flow out the exhaust by-pass, you should be alright. Feel all around the powerhead, not just the cylinder head itself. More than likely your engine is fine. A thermo-couble would be to bulky on this small engine, plus an over-kill.

 

[Scott J]

Re: 1962 Johnson 5.5 Temp. Question

Thanks for the info. I just finished trying this motor out in a bucket of water. I placed the thermocouple wire under a head bolt just to see how it would work. Everything seems to be Ok. When I first started the motor there was very little or no flow out of the exhaust bypass. As it got warmer more and more flow was evident through the bypass. After it was warmed up there was a constant stream of water and the thermocouple was reading about 158 F. Everything appears to be operating properly. I will be taking it out tomorrow for the first time this year.