Evinrude 3 hp and Johnson 4 hp overheating

[martin20]

Have a 55 Evinrude 3 hp,and a 65 Johnson 4 hp,both with overheating problems. Changed impellers,blew out tubes and all orifices. Took heads off and cleaned passages,and exhaust covers,still seem to get hot. Pumping strong,run great. Just seem to get hotter than they should. Water boils when splashed on head. Should it be that hot? Doesn’t seem to affect running. Thanks for any help

[frankr]

Depends on where you are checking it. The flat exhaust cover is only water cooled on the edge and has fire behind it, so it gets blazing hot.
Likewise, the cylinder head is only cooled around the edges and the center portion around the spark plugs gets very hot.

[crosbyman]

pull the LU and spin the shaft while submerged the LU in a bucket to see if lots of water goes up the water tube

if ok… something may be blocking the flow inside the PH but you said all is ok but these motors can run hot to my knowledge the exhaust cover plates are not water cooled and will discolor

is this a new issue that came up??? because you indicate the engines work fine

Joining AOMCI has priviledges 🙂

[martin20]

Just acquired them month ago. Got them running nice,just not sure how hot is normal for them. Had others like it,usually they started running bad when they got too hot and knew for sure they were overheating. These 2 seem to be running fine,although i didnt want to over do it..Guess I’ll try them again. Thanks

[lindy46]

Those little motors do run hot. If you’ve cleaned all the passages and see water coming out, and they run fine, you’re probably OK.

[fleetwin]

OMC didn’t make a 4hp in 65, which other engine do you have? Like Frank says, these things run hot…
That doesn’t mean you engine isn’t overheating, just that it probably isn’t overheating….

[cajuncook1]

Look at the diagrams below, they show the best area to check for head temperature reading. They must be less than 160F degrees. The 3hp and 4hp from 1952 to 1978 did not have thermostats.

[martin20]

Thanks for the replys,will check with a temp gauge

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