Farmall Super A, AV, 1939 - 1954
Moderator: Team Cub
Called the PO and he said he had never had a problem with a carb drip. He stated that he had rebuilt the carb 8/04 with IH/Case parts. I took the carb apart and everything was a clean as could be, put it back together no drip. Who knows what it's problem was, but I am getting to know my tractor better already.
I wish it was the end of the story. Just when I thought I had it fixed, it will run for a while then flood, die and drip. Last night I took it out for a spin and running along in forth gear about Â¾ throttle and all of a sudden it dies. Wonâ€™t restart and then comes the dripping. This darn carburetor is driving me crazy, Iâ€™ve had it on & off about six times now. Iâ€™m getting quite fast at it. I read the tips in lurker Carlâ€™s page and the only thing I havenâ€™t done yet is pull the needle seat out and use some sealer. I just have a hard time believing thatâ€™s it as some times the dripping is more like a full stream. Iâ€™ll take any advice I can get. A new Zenith carb is looking better every day. But Iâ€™m not ready to throw in the towel yet.
Sounds to me like a float with gas in it or a bad or no seating of the float gas shut off valve. Not much else I can think of that would cause your problem. Could be getting small amounts of trash from the tank??.
Then came Bronson
The float is fine, Iâ€™ve submersed it in water for an hour and itâ€™s not leaking. The tank has been cleaned and sealed inside. The sediment bowl is new and the gas in there is crystal clear. So itâ€™s got to be that needle and seat. Maybe the float level? I guess my next move is to get a rebuild kit and swap them out. Do I go to the local Case/IH dealer or is there a better source online? Iâ€™ve read about the Kohler trick on the Cubs but I donâ€™t think that will work for a Farmall A, will it?
I'm going to pick up a needle, seat & bowl gasket after work at the local Case-IH dealer. Since I just bought the tractor and haven't had time to buy a shop manual, could someone please tell me the measurement for the proper float setting.
OK now Iâ€™m at wits end, I installed the new IH needle & seat and its still dripping? I started it up, backed it out of the garage and let it run for half an hour. Ran fine and didnâ€™t die this time. Pulled it back in to the garage less then a minute later not dripping but a steady stream started to flow from the drip hole this time? What the heck is going on? I ordered a repair manual today but other than the float level being wrong Iâ€™m out of ideas. Does anybody know anything about these new reproduction Marvel carburetors? There is one on ebay.
http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... %3AIT&rd=1
I only ever have a slow drip on mine when the A isn't running, so I've not had mine apart, however:
If they're at all like the carbs on the early M's .... there is a little tang that pushes the needle valve back up when the float rises. this can get bent over time. try bending it gently in the direction that would push the needle valve up further into its seat, and see if that does the trick.
The way they get bent is....a piece of crud holds the needle valve down away from its seat, the float rises higher and higher, and puts pressure on the tang...over time, the tang bends.
I know that there's a precise level for setting the float by bending the tang, but from my experience, just enough to stop leaking is a pretty good setting.
Just a suggestion, and if I'm way off base, the experts will correct me, I'm sure.
John, this is a tricky problem to diagnose from a distance. Here's some more things you can check. That eBay carburetor looks like a Zenith - the seller's lousy picture makes it hard to tell.
If your particular carburetor is cast aluminum, make sure the float isn't contacting the bowl casting due to someone beating on the carburetor to stop the leak. Check the castings carefully for cracks, pinholes or other defects.
Having a sealed tank doesn't mean the fuel is clean. Fuel can be contaminated by a deteriorating fuel line.
Shake the float by a good hearing ear and you'll hear liquid splashing inside if the float is a leaker. Immersing the float in water will not determine if it's leaking unless the water is HOT and the float is cool. That's the only time bubbles come out of a leaking float, the bubbles are small and come out slowly. Turn the float over in the water so you'll see the air bubbles from all angles, checking both pontoons.
One other thing to remember - the tractor has a gravity feed fuel system. If you have fuel in the tank, gravity keeps it pressurized whether the tractor is running or parked. Every little crack or crevice that isn't sealed will let fuel come on through. Check the needle cage seat for any corrosion or gouges that could be potential gas leakers.
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John...You might try adding some SEAFOAM (available at NAPA stores) to your gas tank (about 2 to 3 oz. of Seafoam per tank full). Always be sure when your "A" is not running and parked to turn off the gas at the shutoff on the sediment bowl. This will keep any gas from running from your gas tank down into the carburetor.
From what you describe...I'd say your carburetor float is NOT damaged, but is hanging up somewhere on the inside of the carb. It can be something as simple as a gasket that's too large and blocking the float from returning to it's fully closed position.
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