1968 Evinrude Lightwin Cooling

Hi, I have a 1968 3hp Lightwin. It's been a sweet motor and I really enjoy booting around in it.

I was getting ready for the first trip of the summer and put the motor in my test tank... and it got super hot. I wish I had been watching it a little closer, but I'm pretty sure it's okay: no discoloration or anything...

I checked the impellor, it was fine. I searched all over for a thermostat only to learn there isn't one. So I took off the head and exhaust cover and found it was plugged right at the passage you can see from the exhaust side that enters the cylinder cooling jacket. So I think that's problem solved there.

But here's the thing: on examining the cylinder jacket I don't see how the water is forced around the jacket to the water outlet, rather then just going straight from the inlet to the outlet (They are right next to each other). On newer motors I know there are these little rubber "thingy's" that insert into the jacket to force the water to go around. Am I missing something here? I don't see anything on the parts diagram.

Please help. This little engine is way to sweet to have a idiot like me wreck it.

Thanks in advance.

Those little 3 and 4 hp versions run quite warm, you cannot hold your hand on the cylinder head or the exhaust cover while running. I have a half dozen of them and they run 150-175F on the cylinder head and the exhaust cover on the laser temp gage.

Make sure the intake side is clean leading to the pump. There are no water diverters in this motor, but an improved head gasket is available compared to what you had on there. You can surface the cylinder head on a perfectly flat surface like plate glass/old counter top section....and 180 to 240 grit wet or dry paper, use water to aid in debris removal/irrigation. Clean threads well, blow out.....and use a LITTLE anti seize on threads, applying a bit down in threads with a toothpick or little screwdriver.

Ok. Thanks for all the great advice. I feel pretty good about this little job (famous last words), and will post on the result as soon as all the parts get here.

Hi. Waiting for boat parts sucks, but they all eventually did show up.

As recommended, I checked the water passages leading in and out of the engine and am confident those passages are also clear.

I got nervous due to lack of experience on the matter, so did not lap the head.

I put the engine back together and just as stated above, the head and exhaust covers were quite hot, but not overly so like before. The cylinders on the intake side of the engine were not hot: I could put my hand on them all day long.

I think I'm good to go so thanks so much for all your help.

Thanks for the report. I just sold a 4 HP and it was running hot until I changed the head gasket too. Buyer loves it. Take care. Tim

SwervinMervin said:

Hi. Waiting for boat parts sucks, but they all eventually did show up.

As recommended, I checked the water passages leading in and out of the engine and am confident those passages are also clear.

I got nervous due to lack of experience on the matter, so did not lap the head.

I put the engine back together and just as stated above, the head and exhaust covers were quite hot, but not overly so like before. The cylinders on the intake side of the engine were not hot: I could put my hand on them all day long.

I think I'm good to go so thanks so much for all your help.

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Take care of that little engine, if your getting a build up of sand or silt or running in saltwater, keep her flushed out after each trip. That engine was a gift from the OMC gods, simple design, quiet, reliable, and what a wonderful idle. With proper care, it will be around another 50 years.

Haha. for sure I will do my best to take care of it. My favorite thing to do with that engine is see how low an idle I can get it to sustain. It's pretty low! Thanks again and take care.

Gift from the Ole' in the sky....ha! Well said, Fitz! 2 fires per revolution is pretty hard to beat!