1979 Evinrude 55HP: Not peeing water from cowl, heat alarm sounds

[sheamus]

I have 'inherited' a 79 55hp Evinrude which had been sitting for about 5 years. This is the first time I have played with a boat motor, so my terminology may be off, and questions may sound dumb. Bear with me.

The heat alarm went off the first time I used it, so I replaced the impeller on the water pump. The impeller in there was badly melted. But there seems to be no paint discoloration around the head, so I am guessing that no one has ever run it too with coolant not working. Ran the boat, and water did come out the two slot at back of motor, but no small 'pee' stream, and eventually heat alarm went. I am guessing I should have replaced all the parts in the pump, as the metal cup was in pretty rough shape. So I have gone ahead and ordered a new pump kit (rather that just impeller).

I should mention that a fair bit of oil appeared in the barrel I was testing in, not sure if this is normal or not.

1. While I am waiting for the parts, I was wondering about the thermostat. Do I have to take the head off to get at the thermostat? I don't seem to see any sort of thermostat casing anywhere (externally).

2. Should I be able to blow air (with mouth) through the peel hole on back of cowl?

 

[Watermann]

I have a similar 1977 55 HP Johnny and they should be the same. Post your serial just to be sure. I would suggest that you replace the T stat and the rubber grommet for the pop off while your at it. When you have the T stat out try back flushing into the hole with a hose and see if the water free flows out. For the pee hole, use some weed eater trimmer line to poke in the hole and see if there's an obstruction in the line while your flushing. Oh yeah you need to get a new gasket for the head cover, it's not actually the head, just a cover with water jackets. The knot at the bottom is where the T stat is located.

The oil in the water barrel is normal, the exhaust in the water recirculating and will become all mixed up and even foamy gray looking if ran long enough. I would suggest trying a set of muffs just don't over rev the motor just let it idle.

 

[sheamus]

Well I forgot to get the serial, but I did find t-stat. I had to take the water jacket off the head to get at it, and damn near had to take the whole motor out of the cowl to get the jacket off.

Anyways, it was immediately obvious that the t-stat was completely shot. The pressure relief valve immediately above the t-stat was completely melted. Once I removed those I was able to easily blow air through the pee-hole. There was rubber from the first impeller I replaced stuck in the t-stat too. The water jacket was bone dry, likely hasn't been water in there for a while.

Well more parts to buy, but at least I know now.