Marvel Schebler TSX tractor carb rebuild

[legdelimber]

Any chance that the screws and adjusting needle are plated?

edit: Has anyone else become so wary of modern quality control, that you now dismantle new carburetors and check for twisted gaskets or diaphragms or any burrs and lose flashing/debris, before installing any of them?

 

[FergusonTO35]

I don't know, may have to do that. Go the new carb installed today, set it one turn out on both screws. My luck just keeps getting better, my battery was discharged. Charged it for awhile and got it to turn over a few times but didn't do anything. Pulled the plugs and they had some pretty thick fouling, I have some clean ones to swap in there. Lotsa fun...

 

[legdelimber]

Old Carb sounds like it could have been running a bit rich whenever the float /needle was hung.
A load of soot or fouling on the plugs can bleed the spark off instead of letting it jump the gap.

 

[FergusonTO35]

That's what I am thinking.

 

[FergusonTO35]

Ok, looks like we now have the opposite problem. The tractor won't do anything at all with the new carb, but will start and run a bit on brake cleaner. Took the top off the new carb and found the bowl was completely empty. Attached the top half to the fuel line and turned on the gas, nothing came out of the needle and seat. So, looks like I got a bad one.

 

[FergusonTO35]

Took it apart, and it seems the needle won't let gas into the bowl. The needle has a rubber tip on one side and a ball valve on the other. This is a strange design compared to what I usually see on small OPE. The needle tip seemed to be stuck in the seat. Pulled it out, squirted carb cleaner through it, and now seems to operate properly. I squirted cleaner through all the other passages and they are clear. Guess I'll put it back on tomorrow and see what happens.

 

[Steve]

Took it apart, and it seems the needle won't let gas into the bowl. The needle has a rubber tip on one side and a ball valve on the other. This is a strange design compared to what I usually see on small OPE. The needle tip seemed to be stuck in the seat. Pulled it out, squirted carb cleaner through it, and now seems to operate properly. I squirted cleaner through all the other passages and they are clear. Guess I'll put it back on tomorrow and see what happens.
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Sometimes I have had a few new carbs do that. They will sit too long dry and the rubber tip sticks to the new seat. Break it loose and get fuel in it and it will be fine.

 

[FergusonTO35]

Sounds good, hopefully that's all it was. This carb seems to be decent quality for aftermarket.

 

[Al Smith]

It's a relatively simple carb .Because it's made of cast iron it won't get all funky falling apart with the "white death " like if it were aluminum .On a rebuild you just have to make certain all the passages are clear using a set of torch tip cleaners or what ever . At one time they made bushings for the throttle shaft which could be worn eccentric causing leaks . Usually on a tractor not the problem but the version used by Wisconsin on hay bailers with a constant governor action will wear them out .

 

[Steve]

It's a relatively simple carb .Because it's made of cast iron it won't get all funky falling apart with the "white death " like if it were aluminum .On a rebuild you just have to make certain all the passages are clear using a set of torch tip cleaners or what ever . At one time they made bushings for the throttle shaft which could be worn eccentric causing leaks . Usually on a tractor not the problem but the version used by Wisconsin on hay bailers with a constant governor action will wear them out .

Wisconsins also operated at twice the rpm and where not nearly as smooth running as a engine with twice the cylinders. Wisconsin engines have a much smaller displacement than a tractor with damn near the same throttle shaft size. When the shafts wear the carb simply can not supply enough fuel to compensate for the vacuum leak. Also, a small square will easily make a 100hp tractor constantly work the governor too. Wisconsin also almost exclusively used zenith L series carbs. In my experience they are much more picky about adjustments and air leaks than a TSX. The TSX are like an AK-47. Even after thousands of hours and a drop in a river the Marvel carb will work satisfactory without cleaning, rebuild, or adjustment.

 

[Al Smith]

Some of the rebuild kits have a rubber tipped needle some not ,all metal .My little Fergy starts up in any weather .Cold doesn't bother it but hot does . Because the way the fuel line is routed past and close to the exhaust discharge it will over heat and cause a vapor lock .That is only amplified with a big bore kit and that extra 4-5 HP .Not enough radiator . I had to reroute the fuel line out and around .It isn't pretty but it cured the problem .
I'll say this for no larger than it is it will handle a 6 foot flail mower in 12" high grass .However it would over heat on occasion .Often when I used to mow a 2 acre field in front of my house it might vapor lock three times before the job was done .I'd just pop a top and drink a brew until it cooled off . Any more I do that job with a 54" Toro zero turn which doesn't over heat ,does it slightly faster, neater .No beer breaks .

 

[Steve]

Some of the rebuild kits have a rubber tipped needle some not ,all metal .My little Fergy starts up in any weather .Cold doesn't bother it but hot does . Because the way the fuel line is routed past and close to the exhaust discharge it will over heat and cause a vapor lock .That is only amplified with a big bore kit and that extra 4-5 HP .Not enough radiator . I had to reroute the fuel line out and around .It isn't pretty but it cured the problem .
I'll say this for no larger than it is it will handle a 6 foot flail mower in 12" high grass .However it would over heat on occasion .Often when I used to mow a 2 acre field in front of my house it might vapor lock three times before the job was done .I'd just pop a top and drink a brew until it cooled off . Any more I do that job with a 54" Toro zero turn which doesn't over heat ,does it slightly faster, neater .No beer breaks .

I will say that too about the marvel carb. My tractor will start right up till about 30 degrees or so with no choke. Have you tried a brand new radiator Al? Had the same issue with my VAC after I put thinwall sleeves in it. Put a brand new radiator in it and it holds 175 degrees in 100 degree ambient with a 6 foot bush hog behind it. Also have you tried heat insulation tube or wrap on your fuel line?

 

[Al Smith]

I did a little research on that and from what I found it was indeed a Zenith made to kind of like the Marvel design .

 

[Al Smith]

I did try to insulate the fuel line .Tried the old trick used on Y block Ford V8's with a half dozen clip type clothes pins .They helped some but not enough .The radiator has been recored with a brand new McCord core or substitute for same . My only cure was out and around the exhaust using about a foot of rubber line on the end which won't collect heat like a steel line .As far as heat ,the engine doesn't over heat just the fuel line .Of course Fergy being Fergy the oil pressure drops ,most of them do new bearings , rebuilt oil pump it's just something they do . I probably should run SAE 40 WT in summer and SAE 30 WT in winter but I don't .No more hours than I put on it I change the oil every spring .Just once a year .

 

[Steve]

I did try to insulate the fuel line .Tried the old trick used on Y block Ford V8's with a half dozen clip type clothes pins .They helped some but not enough .The radiator has been recored with a brand new McCord core or substitute for same . My only cure was out and around the exhaust using about a foot of rubber line on the end which won't collect heat like a steel line .As far as heat ,the engine doesn't over heat just the fuel line .Of course Fergy being Fergy the oil pressure drops ,most of them do new bearings , rebuilt oil pump it's just something they do . I probably should run SAE 40 WT in summer and SAE 30 WT in winter but I don't .No more hours than I put on it I change the oil every spring .Just once a year .

There are many things I do not like about these tractors. Mainly no live hydraulics. Also when bush hogging A few times a rock or piece of wood smack the back of my leg the way to straddle the transmission. Even with a set of proper chain guards. I like cultivator tractor for mowing chores.

 

[Steve]

I did a little research on that and from what I found it was indeed a Zenith made to kind of like the Marvel design .

I think the zenith carbs run better but not near as reliable as the Marvel

 

[FergusonTO35]

You guys are great, a real wealth of knowledge. Anyway, unsticking the needle did it and she is running again. Yes, I'm going to hook the air filter tube back up!

 

[FergusonTO35]

Found that the brass elbow into the carb only tightens up 180 degrees away from the fuel line so it drips a bit. Cleaned it up and put some Permatex no. 1 on it, hopefully that will be all it needs. Also cleaned up and reinstalled my Champion D18Y plugs which are what it prefers.

 

[Al Smith]

That picture showing fuel line behind the exhaust side of the manifold is exactly what I had talked about .I had to route it clear back under where the battery sits then swing wide around the exhaust pipe to stop the vapor lock .Same deal with the alternator except I used the pulley from the generator with a 5/8" belt .Doesn't turn as fast but does a darn sight better than the generator .

 

[Al Smith]

If you do any mowing ,brush hogging you better install an over run coupler because even standing on the brakes a wound up brush hog can shove you a long ways .Fact I had to retrieve my other Fergy out of a pond once because of that .I got real smart real quick .