150 cooling

[bigcheese]

hi everyone, I have a 1979 150 evinrude that runs cold on the starboard head and very hot on the port head. head gaskets and t stats have been replaced as well as h20 pump. have run unit w/o t stat in port head to check for flow, flow seemed good, and head actually ran cool. have also checked coolant ports with heads off everything was clear. need a guiding hand thanks.

 

[emdsapmgr]

Re: 150 cooling

Does the overheat occur when idling, or at planing speeds? You could try swapping the thermostats, in case one is faulty. Without getting into too much disassembly work, you could remove the head covers and see what the inside of the head water jacket looks like. Occasionally they can fill up with sand or even weeds. I'd figure it out so that you can run the stat in the port head. Did you check the rubber water deflectors when you had the heads off?

 

[bigcheese]

Re: 150 cooling

thanks for the info, I'll try swapping t stats, the old ones did the exact same thing though. I had the head off and inspected the cover and didnt find anything. I'll try it though maybe test it in a bucket of boiling water and see if it opens, never know may have had a run of bad t stats. Whats with the deflectors, their purpose? They were there, and the unit heats up quickly whether in the water or just with the muffs on. thanks for now, will try the t stats.

 

[emdsapmgr]

Re: 150 cooling

The water deflectors look like a 3/8" rubber hose. They are inserted in the block, one for each cylinder. They force the cooling water to take a specific path around the cylinders before the water exits the block into the head. If one of them is missing or deteriorated, the factory-intended water flow path is disrupted and it can lead to an overheat on that side of the block.

 

[bigcheese]

Re: 150 cooling

hey here's a silly but thought provoking question, what temperature should the t stats open? maybe its not running hot but the other side is running to cool, like the t stat is opening to soon?

 

[Benny1963]

Re: 150 cooling

not a silly question i believe 140 or so just change both thermos and poppetts ,its good to keep them fresh

 

[emdsapmgr]

Re: 150 cooling

The thermostats should open at 143. Normally, it idle you should see 143-150 as a head temp. Temps go down when at planing speeds and the pressure relief valves open. Overheat is at 212.