1968 johnson 3 hp white smoke

[Bnbvetter]

I recently replaced head gasket and exhaust plate gasket on my 1968 johnson 3 hp model jwf-23a. The head had previously been warped due to overheating so I got some 400 grit sandpaper and got it to within .003 inch tolerance. (It had warped to about .008 inch in the middle if the head). Anyway, took it to the river for its first run since being repaired and after warming up to operating temp, it began to white smoke a bit from the exhaust ports. Not a whole lot, but enough to make me slow down and check it out. Water was spitting fine from the exhaust ports strong and like it should, and I could hold my fingers on the head for about a 5 count so I don't think it was overheating. I decided to go on at about 3/4 throttle and the smoke seemed to clear up within just a couple minutes. So my question is this: did the head gasket just kind of seal itself after the motor ran for a while?

 

[Robert Ellis]

it wouldn't hurt to check the compression ...it may give you some insight as to the integrity of the head gasket.

 

[Bnbvetter]

Compression isn't great, but the bottom cylinder has some scores in it so I don't know if a compression test will really be able to help in this scenario due to the probable little bit of blow-by that's already there. The motor runs great(for now anyway). Doesn't miss, idles fine, and accelerates quite fine. But yeah your point about the integrity of the head gasket itself makes me wonder. The packaging said johnson/evinrude original parts, but the new one doesn't look near as robust as the old one.