Gasket Sealer and carb question

[Jeff74]

Hello Guys,

I have a 77 Johnson 35hp 35e77c. Leaks fuel from where the air silencer attaches to the carb. There are two gaskets that sit between the air silencer, air silencer support, and the carb. Is it ok to use gasket sealer on these gaskets? If some gasket sealer got into the fuel mix, would that gum up the engine? Also, is it ok to run a bead of marine silicone around the air silencer halves to seal it up?

I definitely want to check what sealers are ok to have that close to the intake on the carb.

Also, could you retro-fit a later model carb on an older engine? It looks like the carb for the 1993 Johnson 35hp's would fit the 1977 35hp. Just out of curiosity.

Thanks for your help. You guys have helped me keep my engine running very smoothly-Jeff.

 

[Okee Jimmy]

Re: Gasket Sealer and carb question

If the leak between the silencer and carb is more than just a drip, you may have a leaky needle, and seat, or improper float level adjustment. Any fuel leaks are potential fire hazards.

I don't like to use sealer on any carb gaskets, other than gluing one side of the silencer gasket just to hold it in place. If sealer is used on the float bowl, gasket, or other parts of the carburetor there is a possibility of it getting into an internal passage that would be very difficult to clean.

You could retro-fit a later model carburetor to your motor as long as it is properly jetted. Re-jetting can take a lot of time and effort, and if not done correctly could cause serious engine damage, also in the end it may not even give much of a performance improvement.

Hope this helps, Jimmy

 

[Jeff74]

Re: Gasket Sealer and carb question

Thanks, Jimmy

The leak is just a drip, however, over the course of a day it creates a mess. It doesn't take much 2 stroke fuel to make a mess, it seems. I'd like to get the leak stopped. I'll keep working on it. -Jeff.

 

[Randybeall]

Re: Gasket Sealer and carb question

If it is enough to make a mess in just one day you are due to overhaul your carbs. I suggest the kit with new float. There are great instructions in frequently asked questions. Find them and print out before you start. When the carbs are working correctly you will get almost no fuel at the front of the carbs.

 

[jtexas]

Re: Gasket Sealer and carb question

randy's right, that gasket shouldn't have to work very hard, I mean there shouldn't be enough fuel coming out the carb throat to make a mess there.

Tilt the motor full up (engine off) and squeeze the primer bulb, see if any fuel drips out - if it does then your float valves are leaky. carb rebuild will fix that.

A little bit of fuel does collect in the airbox -- there's a hose at the bottom to scavenge the oil -- but if your carbs are spitting out fuel at idle, that points to worn out reeds.

Get it running right, you won't need to seal the airbox.

 

[Jeff74]

Re: Gasket Sealer and carb question

Thanks, everyone. Appreciate your time.-Jeff.

 

[Kettler]

Re: Gasket Sealer and carb question

How Ironic.


Took my boat out today with the wife and ran in the oceans 3 ft. seas for a 10 min run WOT and got real wet.

Then we bombed around the ski area 20+ min. or so jumping waves and then tooled around the bays, about a 2 hr. trip total.

Post trip inspection revealed The airbox cover, which the previous owner drilled 1/4" holes in to fog (lazy), had some fuel on it and there was maybe a teaspoon of gas in the engine housing towards the front because we trailer with the engine up .

There was maybe a quarter tsp. of fuel collected inside the airbox by the recovery hole.

Would this be considered normal?

Also should I plug the holes in the cover and could they be the cause of the fuel in the air box?

To plug them I'm thinking round head screw facing out with a nylon nut on the outside.

 

[tomh59]

Re: Gasket Sealer and carb question

I'm having the same issue with a 76' 35hp. Gas leaking to the front of the carb. I'm going to rebuild today. I'll post results later time permitting.
This has been a very interesting and helpfull thread.

 

[tomh59]

Re: Gasket Sealer and carb question

Well I cleaned and rebuilt the carb today. That seems to have taken care of the leaking gas issue. Hope that helps you all. Hopefully now it's just a matter of tweaking in the low speed per Joe Reeves well respected instruction. Gonna toss it in the river to do that.

good luck!

 

[Kettler]

Re: Gasket Sealer and carb question

How much fuel was leaking to the front of you carb?

 

[Jeff74]

Re: Gasket Sealer and carb question

Jeff here again. I'm the original poster. I'm going to do a carb cleaning today also. I'd say it's about a tablespoon of fuel leaking out of the carb over the day.

So, when I tilt the engine up and squeeze the bulb, fuel should not leak out of the carb? I'm going to try that before I clean for a before and after test. I've cleaned the carb before, but I've never done the blow into the fuel hose test to see if the needle was seating properly. The engine runs great otherwise. Johnsons never die!

I'll also post the results of the cleaning. Thanks-Jeff.

 

[jtexas]

Re: Gasket Sealer and carb question

...So, when I tilt the engine up and squeeze the bulb, fuel should not leak out of the carb? ...

when the carb bowl is full, the float valve is shut. if fuel runs out with the motor tilted up then the valve isn't closing, either worn out, misadjusted or sticking for some reason. If fuel doesn't run out but you can use the primer bulb to force it out, then the valve is closing but not very good.