Hmm... Ok, that didn't work out...

odaytripper

Cadet
Joined
Apr 16, 2017
Messages
10
HI!

I finally took my "new" QD-16 1955 Johnson 10 HP out on the water, where it ran real well for about 15 minutes or so then died. I had to be towed back in :(

This is the engine in a previous thread: http://forums.iboats.com/forum/engi...1955-johnson-10hp-qd-16-carb-leaking-gasoline

The only thing I did "new" or different since I ran it before and everything was wonderful was: Filled up the gas. (and the oil, obvs.)

When the engine died, it blew a LOT of white smoke at first (burning oil fierce). Then I got it to sputter a few times and die again with the choke on, until finally it wouldn't even do that anymore.

Engine was not even particularly hot to touch when it died, water cooling was working. It's not seized or anything awful like that.

I used the 24:1 oil ratio recommended for this engine by just about everybody. I used non-ethanol gas and 2-stroke oil.

My suspicion is that I may have, in filling up the tank for the first time in I don't know how long--really, could be two weeks, could be years--I loosened some gunk and clogged hose and or carb up, similar to what happens with ethanol--but without the dissolving hoses aspect.

Any ideas? How do I unclog an old hose and carb?
 

odaytripper

Cadet
Joined
Apr 16, 2017
Messages
10
OK, thanks... I'll check compression and get back to y'all.

BUT: Isn't overheating a symptom of blown head gasket? Because not hot at all. I put my hand right on the block comfortably.
 

oldboat1

Fleet Admiral
Joined
Apr 3, 2002
Messages
9,598
Overheating can blow a gasket, but not a necessary condition. Bolt torque can loosen and heads warp over time with routine running/heating and cooling cycles. River running or salt water use can take a toll too. Not sure you were able to fire up and run after having issues, based on your description, so might not be clear whether it will overheat.

Should do a compression check just based on symptoms, and suspect a head gasket issue. If you do end up replacing the gasket, resurface the head before reassembling. (do that with 400 or 600 grit sandpaper on a flat surface, moving the mating edge in figure 8s until it's uniformly shiny.)
 

boobie

Supreme Mariner
Joined
Nov 5, 2009
Messages
20,826
As said above, check your spark. Should jump a 1/4 " open air gap on a tester.
 

gm280

Supreme Mariner
Joined
Jun 26, 2011
Messages
14,585
Well the key word in your description is "White" smoke. That surely points to water in the combustion process. So I would most certainly check compression first. I get the feeling you will find your problem. JMHO
 

odaytripper

Cadet
Joined
Apr 16, 2017
Messages
10
LOL.

Problem solved: I went to check compression and spark and stuff.

Discovered loose sparkplug.

Still tested things, but put plugs back in. Now she runs again.

So, moral of this story (and my last one) is: tighten everything, because the guy I bought this from didn't.
 

pckeen

Commander
Joined
Jun 20, 2012
Messages
2,067
Love it - simple solution. Glad you didn't start with rebuilding the heads. :lol:
 

oldboat1

Fleet Admiral
Joined
Apr 3, 2002
Messages
9,598
Now wait, you're the guy who's been firing it up! Other assumptions? (Hint: Should replace the impeller on any new-to-you motor.)
 
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