How do you fix leaking carb bowl?

smsscuba

Petty Officer 2nd Class
Joined
Feb 15, 2009
Messages
126
Hi All,

My Johnson 35hp has a leak on the lower carb bowl.It is made of plastic.I have removed the float bowl and placed it against a sheet of glass.I can swear it is almost level.

The thing is, is that there is a raised ring running around the bowl, so if it is flattened on a piece of sandpaper, it will remove the ring. Will this affect the sealing properties of the gasket, or can I make a copy out of gasket material like Flexoid?

Guys, I am grateful for any advice given.
 

kfa4303

Banned
Joined
Sep 17, 2010
Messages
6,094
Re: How do you fix leaking carb bowl?

I would try to leave the ring if at all possible. I suppose it's supposed to "help" the bowl seat into the bowl gasket better. I wonder if perhaps the bowl it being installed too tightly such that it flexes/warps the plastic bowl a bit and allows it to leak. Is it possible to get a metal/aluminum bowl that is more rigid? I'm not sure if there are any liquid gasket type products that would work, but perhaps there is a marine grade product that can be used as a sealant along with the bowl gasket itself. Just thinking outloud. Keep us posted.
 

DargelJohn

Petty Officer 1st Class
Joined
Feb 14, 2010
Messages
337
Re: How do you fix leaking carb bowl?

If you pump the primer bulb, with the motor shut off, does it leak? If so, then your float needle valve is leaking and you need a rebuild. Otherwise, I would try a new bowl gasket and do not over torque the screws. Using a screwdriver, tighten the screws until the natural resistance makes you stop.

Never use any kind of sealant compound on the intake side of an engine: carburetors, intake manifold, reed valves, ect....
 

emdsapmgr

Supreme Mariner
Joined
Dec 9, 2005
Messages
11,551
Re: How do you fix leaking carb bowl?

What year is this engine? OMC made V4/V6 float bowls (for their aluminum carbs) out of plastic in the 1989/1990 timeframe. They all warp and leak fuel at the bowl gasket with age. Bombardier makes replacement aluminum bowls for those particualr models. You can check with Bombardier Customer Service in Waukegan, Ill and see if they have a fix for your specific model/year 35 hp engine. Give them a call. 1-847-689-7090.
 

jonesg

Admiral
Joined
Feb 22, 2008
Messages
7,174
Re: How do you fix leaking carb bowl?

With the carb upside down in your hand, attach fuel line to the inlet , blow through the inlet tube as you tighten the bowl screws.
When the bowls seals you will not be able to blow through the tube.
You'll be surprised at how little torque is required.
Thats how much you're over-tightening the screws.
 

bob johnson

Rear Admiral
Joined
Feb 25, 2009
Messages
4,304
Re: How do you fix leaking carb bowl?

With the carb upside down in your hand, attach fuel line to the inlet , blow through the inlet tube as you tighten the bowl screws.
When the bowls seals you will not be able to blow through the tube.
You'll be surprised at how little torque is required.
Thats how much you're over-tightening the screws.

if you did it that way, are you at risk for thermal expansion leakage as the motor goes through the seasonal temperature changes???? as well as the heat and cold of running and not running???

I just rebuilt my carbs, but have not installed them . I am thinking I tightened them too much based on your explanation....is the damage done?

or can I just loosen and retorque?? will the gasket still be good? been together maybe a week so far

thanks

bob
 
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