Blown headgasket

[Fr. Frank]

Well, after buying this boat last year for $10.40, (plus the $1300 it cost me to go get it) replacing the manifold and riser, carburetor, distributor, putting new upper & lower cables on it & new lower unit bellows, installing a new fresh water tank, sink spigot and pump, and having the canvas sent off to be re-sewn, I finally decided it was ready for a good water test.
I let it burble nicely at the dock in gear for about 1/2 hour at 800-1000 rpms, and fine-tuned the spark advance, and set the dwell on the points perfectly. My deacons both arrived for a little jaunt up and down the bay, and off we went, through the idle zone, and up on plane, 3200 rpms cruise. Wonderful! For about 3 minutes.
Began losing power, came down off plane. Motor sounding rough, loud knocking sound. Shut it off. Opened the engine cover. small amount of steam. Looked for loose hose. Hmmm.
Re-started the motor, it started immediately. Looked at the motor, saw small amount of water & bubbles coming out between the cylinder head and block by #2 cylinder. Shut motor off. pulled spark plugs on all four cylinders. #1 and #4 look normal (some soot), #2 and #3 are squeaky clean. replace plugs, restart motor, pull plug wires one at a time. Power loss pulling #1 & #4, pulling #2 or #3 gives very little change.
Bummer.