1850 gas questions

[fixerupper]

A young man I know bought an 1850 gas with a nice Westendorf WL 40 loader for his acreage. The tractor is in very nice shape but it is overfueling and smoking when it runs. Does this tractor have the same carb as the 4020 gas? It looks like a 4020 aluminum carb to me. If it is the carb I am suspecting it probably has that accelerator pump vacuum piston that is letting gas by and overfueling the engine. It is in my shed but I have not dug into it yet. I need to do the obvious check the choke and air intake routine but the way it runs, it wraps up to full high idle and straightens out somewhat at high idle it does not act like it is being choked.

Also, an electric fuel pump has been added. Is this tractor known for not getting enough fuel through gravity feed or is the electric fuel pump covering up a problem? The carb does not run over when the engine is not running. Could the electric fuel pump be putting too much pressure to the needle and seat? The electric fuel pump is a small rectangular shaped pump with tabs to bolt it down if that means anything. Thanks.

 

[scootergmc]

Yes, I think that it is a Marvel Schebler USX that's on the JDs. You could be on the right track thinking it's the accelerator pump diaphragm.

 

[ziffel]

The carb is the same design as the JD and some others. They were problematic at best. It does have the accelerator pump you
described and if it starts to leak you can experience what you are describing. Basic carb kits are all the parts that can be had.
That pump diaphragm is in the kit. These tractors were built with a mechanical fuel pump located on the right front side on the
engine. As those pumps stopped working or leaking some were replaced with electrical in line pumps and the mechanical pumps were
bypassed. Some guys just ran a line from the bottom of the tank thru an inline filter direct to the carb. We have three of these
at the farm at the farm. Two have had electric fuel pumps installed bypassing the old mechanical pump. It is VERY important not
to use a pump with more then four pounds of pressure. The needle and seat in the carb will not be able to hold back fuel from a
higher pressure pump. I located the pump just above the starter after making a bracket for the job. Run a line from the tank to
the pump than an inline filter and on to the carb. When built the fuel ran from the tank down the right side of the engine to the
pump and back up the right side of the engine, across the back of the engine, and partway down the left side of the engine and
finally to the carb. That fuel absorbed a lot of heat in it's travels around that hot engine block. The big bonus in the pump
upgrade is the rerouting of the fuel lines away from all that heat. Sure cuts down on vapor locking. Some of those old mechanical
pumps have been removed the mounting hole in the block covered with a plate. I did that to one of ours because the pump started
leaking crankcase oil.

 

[ziffel]

Last thing...I forgot to mention these carbs use a fiber float not a brass one. I have never had what is called a sinker. That is a float that has absorbed gas and no longer floats and regulates incoming fuel. The old GM qaudrajet 4 barrel carbs were notted for this. We always replaced those floats when the carbs were opened up. The floats in these are in a very small cavity and can sometimes rub on on the side walls of the carb body. Not likely you will need to readjust the float.

 

[J. Schwiebert]

A word of advice; If you don't have a vacuum gauge and a coupe feet of plastic tubing an Oliver 1850 shop manual (NOT I & T) borrow one. Also M - S was purchased by
Zenith years ao you will need to find parts from several sources. I helped a friend of mine work on one about 5 years and we wound up getting parts from Deere, Ago and -
M _ S. My e-mail is open if you have questions.

 

[ziffel]

Send me your email address and I'll return a pdf copy of the manual. [email protected] Put Marvel Schebler in the subject line.

 

[fixerupper]

Thank you so much J. and ziffel. My son might be doing this work instead of me this time. He is very talented and it's guaranteed he will learn how to do it right.

I have a road block that might pop up in my life fairly soon possibly major back surgery that will put me out of commission for several months. I have had this model of carb apart various times when I had a 1966 105 Deere combine with a 4020 gas engine. I don't have the combine anymore but I still have the engine as a reminder of the old days. It was chugging at idle and using way too much fuel. At the advice of an old Deere mechanic I finally plugged the vacuum hole that mated with the accelerator pump and my fuel economy went from 6 gallons per hour to 4 gallons per hour. The downfall to this is I had to open the throttle very slowly or it would just sit there and stumble and not pick up RPM's but the engine runs wide open while it's at work and the load is steady while the combine is operating so I got by with it.

I do live only 30 miles from Roberts carb. I know them and they know me. We might just take this carb to them and have them work it over. I have heard they have come up with a way to bullet proof this carb but I haven't talked to them directly about it. We told the owner of this tractor what it might cost at Roberts and he didn't seem fazed. Thanks again.

 

[fixerupper]

Thank you so much J. and ziffel. My son might be doing this work instead of me this time. He is very talented and it's guaranteed he will learn how to do it right.

I have a road block that might pop up in my life fairly soon possibly major back surgery that will put me out of commission for several months. I have had this model of carb apart various times when I had a 1966 105 Deere combine with a 4020 gas engine. I don't have the combine anymore but I still have the engine as a reminder of the old days. It was chugging at idle and using way too much fuel. At the advice of an old Deere mechanic I finally plugged the vacuum hole that mated with the accelerator pump and my fuel economy went from 6 gallons per hour to 4 gallons per hour. The downfall to this is I had to open the throttle very slowly or it would just sit there and stumble and not pick up RPM's but the engine runs wide open while it's at work and the load is steady while the combine is operating so I got by with it.

I do live only 30 miles from Roberts carb. I know them and they know me. We might just take this carb to them and have them work it over. I have heard they have come up with a way to bullet proof this carb but I haven't talked to them directly about it. We told the owner of this tractor what it might cost at Roberts and he didn't seem fazed. Thanks again.

This post was edited by fixerupper on 10/10/2021 at 05:28 pm.

 

[mkuhns]

Most likely the accelerator pump diaphragm on the back cover holding. Just repaired 2 of these for the same issue this summer. There are two holes at the top of the rear cover. On is for vacuum and one is
for the fuel passage into the accelerator jet. You can try and pull a vacuum on the one hole in the rear cover and probably it'll just suck fuel from behind the diaphragm.

 

[fixerupper]

(quoted from post at 17:27:43 10/10/21) Most likely the accelerator pump diaphragm on the back cover holding. Just repaired 2 of these for the same issue this summer. There are two holes at the top of the rear cover. On is for vacuum and one is
for the fuel passage into the accelerator jet. You can try and pull a vacuum on the one hole in the rear cover and probably it'll just suck fuel from behind the diaphragm.

Will give it a try. Thanks

 

[GermantownGreen]

good morning from west central Mo.
below i found old posting from you, and need to go down this rabbit hole with my '58 880 spur gear machine.

Re: 880 jumps out of gear in reply to Young tractor, 09-25-2015 08:11:13
FYI for you or anyone else for that matter the bull pinion shafts can be removed without that puller and both axles do not need to be removed to remove the differential. Only the right axle does.

my tractor did not jump out of gear, but has a tooth broke off of the pinion bevel gear in bottom. (we recovered the broke piece)
and have right tire removed, ready to move on, I would like to discuss this further.
thanks wes GG

 

[fixerupper]

Well I took this carb to Roberts and they won't touch it. Period! They can get a diaphragm but it is a month out. I have a week to ten days to get it done. The surgeon wants to schedule me as soon as possible so the clock is ticking. I know one good old Oliver guy who is 50 miles away I can call tomorrow. So that is what the situation is now.

 

[scootergmc]

You could just order it online. There are many vendors who carry the kit.

 

[Mark in Minn.]

I would be almost sure it is the diaprahm. I have a 1750 with the same carb usx 44 and that ran terrible, black smoke etc. but
would run so-so at full throttle but like crap at slower speeds. It took me almost a year but now runs great.
Not all kits have the diaprahm in it so be sure to ask. I got one from Korves Oliver. Fresh in my mind but was hard to diagnose.
Good luck.

 

[fixerupper]

The kit finally came in. A new diaphragm solved the problem. Thanks for the suggestions.

 

[scootergmc]

Good news!