1955 Johnson 10hp QD-16 carb leaking gasoline

[odaytripper]

Hello!

I just picked up this motor. (1955 Johnson 10hp QD-16.) It was inexpensive, starts right up, and I appreciate the old things that were made right.

HOWEVER, during a day of, really, trying to find out if it would break and leave me stranded in the middle of a lake somewhere, I noticed that it seems to be leaking gas from the carb. Not just dampness, but actual drip drops. A significant leak.

I am new to this engine, and actually, this sort of thing in general (although I'm a quick study and I wouldn't have picked up this motor if I didn't plan to learn), but I think the leak is coming from the join between the float chamber and the body of the carb. The leak is definitely at least that high. (It's not the bowl -- too low.)

I took a look at things and the gasket at that join just doesn't seem right. It's too shiny new, and it isn't cut tight to the edges of the metal. It also seems too thick, and the screws at that location seem to not be fully seated, as would happen if a too fat gasket was in there.

So, I think that's the wrong gasket, or a homemade gasket, and that's causing problems.

I'm including a link to a bunch of pictures, because that's how I am. You can see the gasket in question is shiny wet. That's the gas.

I guess my question is, since I'm new to this, how's my diagnosis? Is that gasket wrong? Or is it supposed to be like that? If not the gasket, where is this leak coming from?

Anyone with any thoughts or advice, please chime in. I'll appreciate any and all help.

Thanks!

PICTURES

And, just for giggles, here it is running.

 

[jbuote]

Hey there!!

​I'm pretty new to boating and outboards myself. So for what it's worth... lol..

​I see the screws holding the bowl to the throttle body have a flat head type screw on them. I have to wonder if they aren't torqued tight enough so it's not entirely sealed. I might take a small screwdriver and see if they feel tight or not. If any are loose, I'd tighten them up. Not cranking them tight, but to see if any are loose/not fully snug if you will. I wouldn't go past "Snug" though without knowing what the manual for that engine calls for. Don't want to strip the screws/throttle body

​Then, I'd see if that made a difference in the leak. (gone, or leaks less).
​Finally, I'd plan on getting the manual for that engine, and carb rebuild kit, and learning how to, and then rebuilding the carb just so I know I have the proper float, float valve, gaskets etc. even if snugging them up works.

​It may have the correct gasket on it now, but if you question it, redo it so you know for sure...
​That's what I'd do, but again.., I'm very new to this myself, so others may have better answers...

​Hope it helps!

 

[F_R]

Looks normal as far as parts go.. But it shouldn't be that full of gas. Suspect the float valve is not shutting off 100%.

EDIT: Upon further consideration, even if over filled, the gasket should not be leaking. That is a soft gasket and should squeeze to conform to any small irregularities in the surfaces. Maybe the screws are not tightened properly.

EDIT, EDIT: Upon even further consideration, the gas goes through a hole in the gasket before it gets to the float valve. So even if the float valve is 100%, the gas can leak out before it even gets to the float valve. My diagnosis: Tighten the durn screws.

 

[lindy46]

Agree with tightening the screws. Then if problem persists, get a carb kit and rebuild the carb.

 

[odaytripper]

so, tightening up the screws seems to have helped.

thanks for helping me notice the obvious :|

 

[jbuote]

Glad it helped! Hope you have lots of fun with that engine!