Marvel Schebler TSX-706 leaking

[Kurt J]

Hello all! I have a Marvel Schebler TSX-706 carburetor with a leak. It was not leaking until recently. With engine off it slowly weeps from the bottom of the bowl at the brass screen (see picture attached). It is not leaking from the plug. I suspect this is from a float needle that is not seating due to sediment or potentially a float with a hole in it? Your input would be appreciated before I dig into it. I've run it a few times and the leak remains the same after sitting. Thanks in advance.

 

[L.B,]

Ya it probably is --float has a hole needle and seat not working right. The spot it drains from is made just for that perpose.
It is called sinister. This is why you shut your fuel off when tractor is not in use.

 

[Kurt J]

Thanks for the reply. I do shut the fuel off each time. I think is is just the fuel in the line making its way via gravity. I will proceed with investigating the needle not seating or a float issue. Thanks again!

 

[L.B,]

After looking at the photo you might remove the drain plug take a close look at the drain receptical make sure its does not have a small crack as that fuel can go where it wants and when you roll it over it circles where it wants. If it is cracked it can be braized.

 

[Tim PloughNman Daley]

ALL M/C CARBS are built the same. Visually inspect the entire Carb and Sediment Bulb for other areas that may be leaking. A usual suspect if so is the Valve Stem, the only actual wear part in the fuel line. Cross-threaded compression fittings are next. Brake & Fuel Lines use a special thread size - 7/16-24 -UNS and if they get incorrectly fitted, can cause leaks. Loosen the Air Cleaner Tube Rubber Hose Connection at the Carb first and observe if there is gas leaking thru the throat. It should be dry. If wet with gas, a faulty float may be the root cause problem. If dry, Perform The Fuel Flow Test. With the 1/8 NPT Drain Plug removed, open Sediment Bulb Valve Stem 2 Turns and have a coffee can underneath to catch any fuel. Flow unobstructed should be approx 1 pint in 2 minutes. Next to the Drain Plug is the SINTERED BRONZE overflow drain screen. This is what it for and what you are seeing and don't believe it is a faulty or cracked part. Other possibilities are that you have the wrong float. The TSX-706 Carb is used on the FORD 172 CID 800 & 900 Tractors and is a larger unit than the TSX-33 & TSX-241 Carbs used on the N-Series Models. Thus the float is a bit larger as well. Float height to be set at 1/4 at nearest point. Check Needle & Float Valve too --- new ones have an extra clip to hinge to float. I advise to investigate all these other possibilities before you try to pull the screen. I can send you a Marvel-Schebler Parts Catalog and some of my own carb documents if you want to email me.


Tim Daley(MI)

 

[Tim PloughNman Daley]

LB - the term is SINTERED BRONZE, made to be porous so it can drain excess overflow. Though some will curse it as being sinister and evil when this occurs... ; > )


Tim Daley(MI)

 

[Abbby]

LB is most likely correct. Replace needle and seat along with checking that float does in fact float. At this point do not run down the path of "unlikely" that others like to confuse you with. Good idea to make sure leak is not coming from drain plug.

 

[wore out]

(quoted from post at 04:39:07 10/21/22) LB is most likely correct. Replace needle and seat along with checking that float does in fact float.

When replacing the inlet valve seat the gasket must be in place and the seat must be TIGHT.

Use a WIDE screwdriver or bit that fits the slot in the seat and engages the full width and TIGHTEN it down, as gasoline will sneak past the paper gasket if the seat isn't tight enough.

In addition to checking if there's any gasoline sloshing around inside the (at that point LEAKY) float, look closely to check that the float is not bent and is symmetrical from side to side and look CLOSELY for any shiny spots that indicate the float is contacting/dragging against the float bowl and bend/correct as needed.

 

[L.B,]

Thanks Tim. I have seen them removed and lead plugs put in thats sin/ster