Why does my carb leak it's been rebuilt.

[farmalldave]

My farmall 806 with the c301 engine has a carb that leaks out the throat or front where my finger is pointing. I have soaked my carb cleaned out all ports with wire and small brush. I have blown out each port with air. I have a new needle and seat that I ordered from steiners . It still leaks. The screen on the end of my gas line rusted off so I removed that entire screen. Does that screen help slow down the flow so the carb doesn't over fill. I understand the float and needle perform that task but at this point having removed the carb twenty times I'm just wondering.

 

[farmalldave]

Carb

 

[old]

My farmall 806 with the c301 engine has a carb that leaks out the throat or front where my finger is pointing. I have soaked my carb cleaned out all ports with wire and small brush. I have blown out each port with air. I have a new needle and seat that I ordered from steiners . It still leaks. The screen on the end of my gas line rusted off so I removed that entire screen. Does that screen help slow down the flow so the carb doesn't over fill. I understand the float and needle perform that task but at this point having removed the carb twenty times I'm just wondering.

I most case like yours the float is not working as it should or the needle seat is not as tight as it needs to be and leaks. If the new needle has a rubber tip you need to put a set in the rubber tip by putting it in the seat and tapping on it with the handle of a screw driver or other such thing

 

[Curt Cooke]

I think that often when the bottom half of the carb is assembled to the top half, there is interference with the free motion of the float. Once assembled I always tip the carb upside down and right side up several times with it close to my ear to make sure I can hear the float freely moving up and down. I also prefer the old type needle, brass to brass. Too many times I've experienced having the neoprene tip stick in the seat. Just my experience, I'm no expert.

 

[grandpa Love]

Does your float have a hole in it? Sink it in a glass of water,hold it down with something, leave it a while,see if it fills with water

 

[used red MN]

Does your float have a hole in it? Sink it in a glass of water,hold it down with something, leave it a while,see if it fills with water

If you place it in a glass/jar with hot water in it you can watch closely within the first 30 seconds. The hot water expands the air in the pontoons and then it exits through any holes/breaks causing bubbles.

 

[Jim Becker]

All it would take is one little bit of trash (like maybe a rust flake) that gets past your non-existent screen and lodges in the float valve.

Of course, the possibilities vary depending on when it is leaking, which you didn't specify -- whenever it is not running, when it is running, after a failed attempt to start it . . .

 

[farmalldave]

Does your float have a hole in it? Sink it in a glass of water,hold it down with something, leave it a while,see if it fills with water

I tested the float it floats no holes

 

[farmalldave]

All it would take is one little bit of trash (like maybe a rust flake) that gets past your non-existent screen and lodges in the float valve.

Of course, the possibilities vary depending on when it is leaking, which you didn't specify -- whenever it is not running, when it is running, after a failed attempt to start it . . .

It leaks as soon as I turn the gas on. I have had it off and on about twenty times. The carb

 

[Jim Becker]

It leaks as soon as I turn the gas on. I have had it off and on about twenty times. The carb

In that case, it could be any of the above.

 

[used red MN]

All it would take is one little bit of trash (like maybe a rust flake) that gets past your non-existent screen and lodges in the float valve.

It still leaks. The screen on the end of my gas line rusted off so I removed that entire screen.

I agree with Jim. That screen for the most part keeps out crud that gets between the float needle and seat, then it doesn’t seal well and leaks as you’re experiencing. Get a new fitting with a strainer screen. If you still have problems look at this thread it shows how to test the carb top on the bench in my reply 8. Another dripping carb thread

 

[Mrfred54]

Remove the drain plug then install a barb fitting in the drain hole and then a clear hose to the fitting and hold the hose so it’s above the carb and turn on the gas . The clear hose will tell you where the fuel level is in the bowl. If it’s level with the bowl gasket that is too high. Should be about a 1/2 in below the gasket line. I do this on every carb I rebuild on the bench. I just use an old coffee can with a barb solder to the can and hook it to the carb. Comes down to three possibilities. Float is bad or sticks in the bowl, needle and seat bad or dirty, or a crack in the casting internally.

 

[the tractior vet]

Remove the drain plug then install a barb fitting in the drain hole and then a clear hose to the fitting and hold the hose so it’s above the carb and turn on the gas . The clear hose will tell you where the fuel level is in the bowl. If it’s level with the bowl gasket that is too high. Should be about a 1/2 in below the gasket line. I do this on every carb I rebuild on the bench. I just use an old coffee can with a barb solder to the can and hook it to the carb. Comes down to three possibilities. Float is bad or sticks in the bowl, needle and seat bad or dirty, or a crack in the casting internally.

Nothing like a wet bench test on a gravity system for pressure feeds i use and electric fuel pump . So far this year i have not had one carb come in . Usually at this time of year it is carbs off grain trucks , guess i have them all fixed . I did a boat load of Holley's off I H grain trucks . They say ya can't get carb kits for them. This is true BUT oh wait it's the same two BBL. carb used on Chrysler 400 engines and everything in the kit for a Chrysler works in the Holley on the 404 I H . On the goved Four BBL iother then the Gov. stuff and power valve will work ya just have to get the correct power valve as most times this is the issue on them. Doing a wet bench set on the Holley Four BBL is a whole lot safer then on a running engine .

 

[Absent Minded Farmer]

So far this year i have not had one carb come in

I can send you two, if you really miss working on them.

All humor aside, updraft carbs have to be about the easiest to work on.

Except for the Tillotson carb that was on my Model AA. I monkeyed with that thing all summer until I realized there was a pinhole leak in the casting, bypassing.... I think it was the venturi.

After further thought....

That was 32 years ago!!

And I had three carbs for it. The Tillotson was for moving around the field, the Zenith was for parades & the Stromberg was to get a load up a hill on the road. Well.... trying to keep it above 15 MPH without overheating.

Mike

 

[farmalldave]

Fixed the leak the bracket that holds the float was not level float scratching the side . I turned the carb upside down and could hear it moving . My next question is what's the best way to wire the fuel shut off solenoid on the back of the carb. I was reading and one option is the positive side of the coil. Will running a wire from positive side of coil to the fuel shut off solenoid work safely.

 

[farmalldave]

I can send you two, if you really miss working on them.

All humor aside, updraft carbs have to be about the easiest to work on.

Except for the Tillotson carb that was on my Model AA. I monkeyed with that thing all summer until I realized there was a pinhole leak in the casting, bypassing.... I think it was the venturi.

After further thought....

That was 32 years ago!!

And I had three carbs for it. The Tillotson was for moving around the field, the Zenith was for parades & the Stromberg was to get a load up a hill on the road. Well.... trying to keep it above 15 MPH without overheating.

Mike

Lol yeah I got this one figured out.

 

[Jim.ME]

Fixed the leak the bracket that holds the float was not level float scratching the side . I turned the carb upside down and could hear it moving . My next question is what's the best way to wire the fuel shut off solenoid on the back of the carb. I was reading and one option is the positive side of the coil. Will running a wire from positive side of coil to the fuel shut off solenoid work safely.

From the coil would work, it would wire to the same terminal on the coil as the wire from the ignition switch. Or you could wire it to the ignition terminal of the switch, same terminal as the coil gets power from.