Overheating, maybe?

[thedeer93]

I have a 1938 Johnson LT-38. It will run for about five minutes. Then, it starts running rough and dies completely. After it cools down, it will crank right back up. I have a feeling that it is overheating, but would like to be sure. I know that it does not have an impeller, but a "mechanical piston pump". Is there some kind of heat-tape that changes color when a certain temperature is reached, or any other way of knowing for sure? Help of any kind would be appreciated.
Thanks,
Erik

 

[northernmerc]

Re: Overheating, maybe?

Have you tried a hand held laser thermometer? They are cheap and work great. Just point it at the head.

I have no idea how hot that motor should run. But more modern motors likely should not run above 160 F or so.

 

[kenmyfam]

Re: Overheating, maybe?

Hand held thermometer is the best bet. Alternatively yo can get temperature sticks. These are crayons that melt at different temperatures.

 

[bktheking]

Re: Overheating, maybe?

My favourite tool in my toolbox, got mine on sale for $30.