1963 18hp - overheated and died?

[BigB9000]

So I got ye old 18hp evinrude.

Cleaned the carbs, new coils, plugs, impeller.

I gave it a test tank run, no water dribbling down. So I dropped the lower unit and removed the thermostat and cover, and with the air compressor I blew down the thermostat area, forcing sand and gunk out the copper water pump tube.

Then I fliped the engine over, and blew air down the copper line, forcing sand and gunk out the thermo hole.

Reinstalled everything, and gave it a test tank run again. water dribbled down.
everything seemed ok.

Installed engine onto boat-

Launched the boat, started engine, and headed up the (colorado) river for about 60 seconds at 1/2 throttle, the turned around and headed back to check temp, prop, whatever, and make sure everything was ok.
it died 20 seconds later.

Put it back on the trailer, and removed the cover.

engine was very hot, like, sizzle water droplets off hot.

let it cool for a few hours, took the plugs out, put some premix down there, turned the flywheel a couple of times, installed plugs, and started it up.

started right up. but felt and sounded weaker, and pull cord seems easier to pull.

think I fired the rings? lost compression? everything a ok?

 

[F_R]

Re: 1963 18hp - overheated and died?

You aren't going to like my answer, but you have to face the truth. You need to pull the powerhead and replace the head gasket and exhaust cover gaskets. I'll guarantee they will leak if you don't. Leaking to the outside isn't so bad, but leaking to the inside can be disasterous.

While you have the exhaust covers off, you can look in and see the piston skirts. If they are scarred up, you have problems. How lucky are you feeling today?

Finally, you obviously need to find out what you did wrong in the water pump. My guess is that you missed the water tube / grommet. Stick it in the upper one first, and then you can see what you are doing as you go for the lower one.