Why would a freshly overhauled carb be leaking?

[bowman316]

Back in June, We had the carb on our 1954 mcfarmall tractor rebuilt/overhauled. And It seemed like all summer the gas tank was always empty. Then I just recently discovered that the carb is leaking gas out of the bottom at a steady drip.

How could a rebuilt carb be leaking?
He thinks the rebuild kit he got was sitting on the shelf for 15 years, since it is a 1954 tractor.
It is leaking out of a cylinder that comes off the bottom of the carb, and it has a little thing in the end that looks like a bolt head, with a pin hole in the middle. Think it might be a vent for air?

I did run the tractor for a few minutes the next day, and it did not leak, but maybe the gas just did not really get flowing yet. I am not sure if it leaks when it is running, since I am driving, and can not see. It may only leak when off...

 

[a70eliminator]

Re: Why would a freshly overhauled carb be leaking?

Just shut the fuel off when not in use, sounds like the float valve (needle & seat) is leaking through, not too quality of a rebuild was it?

 

[Bob_VT]

Re: Why would a freshly overhauled carb be leaking?

I will bet the float is adjusted too high

 

[i386]

Re: Why would a freshly overhauled carb be leaking?

Some carbs have a screw for draining the float bowl?

 

[j_martin]

Re: Why would a freshly overhauled carb be leaking?

The needle is leaking forward, or the gasket under the seat wasn't replaced or is missing, or the float is slightly too high. A little junk in the gas, or a piece of fuel hose liner will often make it leak like that.

There should be a gas shutoff, and it should be shut off when you don't use the tractor. I shut my gas off and let the engine run till it starves, then shut off the ignition. It always has fresh gas in the carb when I start that way.

hope it helps
John

 

[EddiePetty]

Re: Why would a freshly overhauled carb be leaking?

........It is leaking out of a cylinder that comes off the bottom of the carb, and it has a little thing in the end that looks like a bolt head...

I'm pretty sure you have a Zenith carb. There are probably two fittings on the bottom. One just after the butterfly (which is a drain for liquid fuel) and the other is a drain plug for the float bowl (to drain the bowl if water is ingested or for storage).
I routinely close the fuel supply valve when shutting down AND drain the bowl via a drain **** installed in the bowl's plug position.
As previously suggested by others, the slightest bit of trash, ill-adjusted float setting and/or excessive pressure from the tank (commonly caused by either a full tank or one that the cap's vent is clogged allowing pressure to build when warm)will cause leakage when not in use.
Not noticing any leakage nor reporting a rich mixture when running lends me to believe it's either the needle/seat, dirt or excessive pressure.
The simple solution is to close the fuel shut-off when not in use.
FWIW...Ed in 'ol Virginny

'44 Farmall 'A'
'44 Farmall 'B'
'48 Allis Chalmers 'C'
'53 Farmall 'C'

 

[DECK SWABBER 58]

Re: Why would a freshly overhauled carb be leaking?

Some carbs have a screw for draining the float bowl?

If the cylinder you are describing is the float bowl, that is exactly what is going on.
Most old tractors have a drain screw in the bottom of the bowl. Try tightening it.

A float issue would not cause this problem, assuming what you are describing is in fact on the bottom of the float bowl. The float bowl is always filled with gas unless you run the carb dry.

 

[bowman316]

Re: Why would a freshly overhauled carb be leaking?

but if you run the carb dry, won't it take forever to start. Since you have to get gas back into the carb? Like when a car runs out of gas?
When I was running it, it was hot, and the fuel was leaking like crazy when i shut if off for 20 mins. Then It took me 5 mins to start it back up.
btw, there is no way to tighten the leaking mechnisim, from the outside. It is just a smooth surface on the outside. I might take the carb apart and try to tighten it from the inside.
I can see where the float bowl is, and this is a smaller cyliner comming off the bottom of the bowl.

 

[DECK SWABBER 58]

Re: Why would a freshly overhauled carb be leaking?

but if you run the carb dry, won't it take forever to start. Since you have to get gas back into the carb? Like when a car runs out of gas?
When I was running it, it was hot, and the fuel was leaking like crazy when i shut if off for 20 mins. Then It took me 5 mins to start it back up.
btw, there is no way to tighten the leaking mechnisim, from the outside. It is just a smooth surface on the outside. I might take the carb apart and try to tighten it from the inside.
I can see where the float bowl is, and this is a smaller cyliner comming off the bottom of the bowl.

YES, running it out of gas it will take longer to start.

Sound's like it's time for JB weld to me. Maybe some old tractor guy's will see this post and help. Or try antiquetractors.com
GOOD LUCK

 

[j_martin]

Re: Why would a freshly overhauled carb be leaking?

but if you run the carb dry, won't it take forever to start. Since you have to get gas back into the carb? Like when a car runs out of gas?
When I was running it, it was hot, and the fuel was leaking like crazy when i shut if off for 20 mins. Then It took me 5 mins to start it back up.
btw, there is no way to tighten the leaking mechnisim, from the outside. It is just a smooth surface on the outside. I might take the carb apart and try to tighten it from the inside.
I can see where the float bowl is, and this is a smaller cyliner comming off the bottom of the bowl.

When you turn the fuel back on, give it 30 seconds or so to fill the float bowl on the carb before you crank the engine.

 

[kenmyfam]

Re: Why would a freshly overhauled carb be leaking?

Time for another teardown, diagnosis and rebuild I think.

 

[Splat]

Re: Why would a freshly overhauled carb be leaking?

You need to check you oil VERY well. If the oil level is raised, or thinned it needs to be changed. Many time when the carb leaks it will fill a cylinerd up with gas. This gas will seep down past the rings (called wash down) and into the crank case thinning out the oil.

Just pull the dipstick and smell it. If you smell gas change the oil before running it anymore.

Bill

 

[EddiePetty]

Re: Why would a freshly overhauled carb be leaking?

You need to check you oil VERY well. If the oil level is raised, or thinned it needs to be changed. Many time when the carb leaks it will fill a cylinerd up with gas. This gas will seep down past the rings (called wash down) and into the crank case thinning out the oil.

Just pull the dipstick and smell it. If you smell gas change the oil before running it anymore.

Bill

Hey SPLAT !!!! It's an UP-DRAFT carb !!!

 

[Splat]

Re: Why would a freshly overhauled carb be leaking?

Hey SPLAT !!!! It's an UP-DRAFT carb !!!

Then I stand corrected, the only chance of anything really flooding would be the AC.

Bill

 

[bowman316]

Re: Why would a freshly overhauled carb be leaking?

I ran this tractor again after discovering the problem, and the second time, nothing leaked. I ran the tractor for 10 minutes or so, then shut it off for a few minutes, and left the gas on.
And it did not leak. then started it back up, and took it back to the shed, and then shut off gas again. It did not leak at all.

Unless it was leaking while i was runnig it. But i don't think it was. It was jsut had to see while i was driving it.

 

[jaxnjil]

Re: Why would a freshly overhauled carb be leaking?

back in the day and still hold true today.

all these vintage tractors had fuel shut offs. all i know of used gravity flow fuel systems and most i can think of, use up draft carburetors.

shut off fuel when done for the day and turn on next morning or when you use again.

draining carb will not effect the next time you start if you have fuel in tank

 

[j_martin]

Re: Why would a freshly overhauled carb be leaking?

When I shut down my WD45, I shut off the fuel and let it run till it stalls, then turn off the ignition. That way, I have fresh gas in the carb and the needle valve is open and not stuck shut next time I run it. If it's been awhile I'll throw in a couple of gallons of new gas so there's enough volatile top to fire when I crank it. It'll burn durn near anything once it's running.

 

[rbh]

Re: Why would a freshly overhauled carb be leaking?

I did not even read the other posts YUP butt head
your float and main needle and seat are not doin their job.
fresh floats + needle and seat, aint I a stinker
(When humour goes bad) see above

 

[j_martin]

Re: Why would a freshly overhauled carb be leaking?

I did not even read the other posts YUP butt head
your float and main needle and seat are not doin their job.
fresh floats + needle and seat, aint I a stinker

Just noticed your location.....beyond hope.

Ain't that the truth?

 

[DECK SWABBER 58]

Re: Why would a freshly overhauled carb be leaking?

When I shut down my WD45, I shut off the fuel and let it run till it stalls, then turn off the ignition. That way, I have fresh gas in the carb and the needle valve is open and not stuck shut next time I run it. If it's been awhile I'll throw in a couple of gallons of new gas so there's enough volatile top to fire when I crank it. It'll burn durn near anything once it's running.

A WD45 is one heck of a tractor.
A friend bought a '57 from his elderly neighbor who had overheated it and cracked the head. Head was replaced but never started. It sat for a couple of years with the crankcase full of water. The engine was locked. Drained the water, filled the cylinders with diesel fuel, let it sit for a few hours. On the 7th or 8th hit of the starter it broke free. New plugs, points, etc. and it fired right up.

Then we fixed the leaking water pump and broken temp. guage.
Smokes a little but runs like a top.