Marvel-Schebler carb choke shaft packing

[CFB]

Hello All,
warm day today so went out to start the tractor. After waiting a bit after opening the fuel valve, I went back to a pool of gas under the carb. Fortunately I
had cardboard and a steel tray underneath that caught most of it. I thought maybe I did not tighten the drain plug as I had it off recently to check the flow,
but after drying around it and laying on my back, I saw the gas coming out where the choke shaft enters.
I see in my FO-4 manual that there is packing around this shaft, part 8N9689. I read in a forum post from a few years ago that the packing of the throttle is
a seal whereas the packing on the choke shaft is felt or a cotton type ball.

a. maybe a dumb question, but do I have to take the carb off the tractor and dismantle it , taking out the choke shaft to get the packing in? Looking at that
spring sort of scares me, but I get scared trying anything for the first time. That's why I contact you guys first.

I have a '49 8N. I rebuilt the carb a few years ago and replaced the fuel line and it has started great ever since. With the tractor as old as it is, should
I have been proactive and replaced this packing at that time since the carb was off? Or does this as well as the throttle shaft packing/seal fall in the
category if it ain't broke don't fix it ? I'll have to dig out the kit I used to see if it even had this cotton ball packing included.

thank for the help. cb

 

[wore out]

(quoted from post at 20:26:50 11/17/21)

There is a felt ring DUST seal around the choke shaft, it is not designed to seal gasoline as there should be no gasoline in that area for it to seal.

Obviously, your carburetor's float bowl has "run over" due to the inlet needle and valve not sealing, a "heavy" float, or other issues.

There's a "drain" port in the bottom of the carb inlet air passage that is supposed to drain out any gasoline that accumulates there,so it would never reach the level of the choke shaft.

The drain contains a "horse hair" or "sintered bronze" filter insert which must be clogged or the excess gasoline would be draining there.

So you need to find and repair the cause of the float not being able to control the level of gasoline in the float bowl.

Also, it's a good idea to shut the gas off at the sediment bowl when the tractor is not in used to eliminate the chance of an incident like you have experienced happening.

 

[Bob Bancroft]

Back when I worked on carburetors I usually replaced the throttle shaft seal. Some times the throttle shaft. I don't ever recall removing a choke shaft. Often the spring on the choke plate relief was gone. But as you've already been told, your problem is the needle/seat/float area.

 

[CFB]

Thank you both. Off it comes. I'll have to refamiliarize myself with these parts. Maybe I just need a new float. But I will pay attention to these other parts and learn what each does. I wonder if I did something to cause this when I had it apart a few years ago. Well, better that it happened at home then someplace else. I don't know much, but I am happy that I have been consistent in following your tip to always close the fuel valve when not in use - now I have a great example why.

 

[Steve@Advance]

Chances are the reason it flooded was trash in the needle valve (it only takes a microscopic piece), or the float is sunk.

Possibly the needle valve can be flushed by running it with the fuel off until it runs empty, then turn the fuel back on, let it fill, and see what happens. If the tank is flaking rust or dirty, this will be an ongoing problem. Gravity systems don't do well with inline filters.

If you go in, give the float the shake test, feel for gas inside one of the pontoons.

You can get all the adjustment specs online, especially the float level, that's critical.

I would not take the throttle or choke shafts out! The screws may be bradded in, and may twist off. Getting the throttle plate back in and centered is critical, best leave them alone unless there is a real problem. A little leakage around the shaft will not be noticeable.

 

[CFB]

Thanks Steve, I might just start it, nothing to lose - and gives me a little time to get motivated to tackle the carb again. But who knows. I know all the filters are in place, but if it only takes a tiny spec. well ... I wish I knew more the first time I had it apart, I should have noted better the condition of the float.