'41 Farmall M Hydraulics

[TimD in MN]

I just got a 1941 Farmall M with a New Idea 503a loader already attached. After getting the Farmall running I tried the loader to check the operation. The tractor just has a belly pump, no live hydraulics. The loader rises ok but when I lower it, fluid starts spraying out of the fill plug vent. The loader is hooked up to the right-side supply from the pump, and the return is located at the bottom drain port. I am wondering if the return should be relocated to the fill port with a tee and raising the fill plug up or do I have a possible issue with the hydraulic cylinders on the loader getting air into the system causing the excessive return pressure? If I lower the loader very slowly, I don't have the fluid spraying out the cap. The other thing is there is no fluid dipstick to check the fluid level, so I don't know if it is over filled or not. Any suggestions would be helpful. Thanks

 

[NY 986]

I just got a 1941 Farmall M with a New Idea 503a loader already attached. After getting the Farmall running I tried the loader to check the operation. The tractor just has a belly pump, no live hydraulics. The loader rises ok but when I lower it, fluid starts spraying out of the fill plug vent. The loader is hooked up to the right-side supply from the pump, and the return is located at the bottom drain port. I am wondering if the return should be relocated to the fill port with a tee and raising the fill plug up or do I have a possible issue with the hydraulic cylinders on the loader getting air into the system causing the excessive return pressure? If I lower the loader very slowly, I don't have the fluid spraying out the cap. The other thing is there is no fluid dipstick to check the fluid level, so I don't know if it is over filled or not. Any suggestions would be helpful. Thanks

The single acting cylinders for the loader on my M are routed to the forward port on the left side. I suspect that the larger problem for you is the volume for your cylinders are on the high side versus the capacity of the Liftall reservoir overloading the reservoir when the oil is returned to it. Creating a vortex of air and oil with only one way out for the increase in pressure when lowering the loader.

 

[TimD in MN]

Thanks for the response NY 986. I'm wondering if I would have to mount a auxilary tank to it for the extra volume of the cylinders then, or would it do the same thing anyway?

 

[Janicholson]

The Pump reservoir is about 6 quarts. Assess the volume of the cylinders and calculate the volume needed. A reservoir is not a bad idea. Have it at the level of the internal reservoir so if can share fluid level. Have the return go into the top of the reservoir, and connect the bottom (or near bottom) to the drain of the internal reservoir. 2 or 3 gallons will do and keep the oil cool. Jim

 

[caterpillar guy]

If you mounted a 5 gallon reservoir some place close to the pump and above the pump return level it could just drain back to the pump as needed. I would check with a couple pails if that is enough capacity for your loader.

 

[BarnyardEngineering]

The loader came installed on the tractor, right? Presumably, it was being used the way that it is before you bought it. No extra reservoir. You should not need to add a reservoir.

You mention a "return." Where does this return come from? These old loaders often used the top of the cylinders as an auxiliary reservoir, to return enough oil back to the tractor to raise the loader.

Did you add oil at any time while the loader was raised at all?

The dipstick is often missing. Full is basically full to the top when the loader is fully lowered to the ground and as much oil is returned to the reservoir as possible.

 

[TimD in MN]

Thanks for the response Janicholson and Caterpillar guy. The loader didn't obviously come with a auxilary tank so I'll do some looking into those.
BarnyardEngineering yes the loader came with the tractor already installed. My uncle had bought it with the loader installed and used it for several years but I have no idea if it was having this problem while he used it. Unfortunately I can't ask him because of some strokes he has suffered. The tractor has been stored in side a shed for a few years. As it is set up right now, the pressure to the loader is connected to the right side port of the belly pump. The fluid return line is connected to the bottom of the belly pump (the drain plug). The hose connections to the cylinders are at the top of the rams, both feed and fluid return. Not the typical connection at the top and bottom of the cylinder housing other loaders I've seen. I have not added any fluid to it yet. I want to eventually change it to Hy Tran fluid but would like to solve this issue first. I did go to the AGCO site and look at the online parts book. I am assuming I have the Low Pressure Double-Action Cylinders they show for a 503A loader. There are no markings in the cylinders that I can find. I figured the dipstick was missing or has possibly fallen into the bottom of the belly pump

 

[NY 986]

Thanks for the response Janicholson and Caterpillar guy. The loader didn't obviously come with a auxilary tank so I'll do some looking into those.
BarnyardEngineering yes the loader came with the tractor already installed. My uncle had bought it with the loader installed and used it for several years but I have no idea if it was having this problem while he used it. Unfortunately I can't ask him because of some strokes he has suffered. The tractor has been stored in side a shed for a few years. As it is set up right now, the pressure to the loader is connected to the right side port of the belly pump. The fluid return line is connected to the bottom of the belly pump (the drain plug). The hose connections to the cylinders are at the top of the rams, both feed and fluid return. Not the typical connection at the top and bottom of the cylinder housing other loaders I've seen. I have not added any fluid to it yet. I want to eventually change it to Hy Tran fluid but would like to solve this issue first. I did go to the AGCO site and look at the online parts book. I am assuming I have the Low Pressure Double-Action Cylinders they show for a 503A loader. There are no markings in the cylinders that I can find. I figured the dipstick was missing or has possibly fallen into the bottom of the belly pump

The Lift-all system is single acting without adding an original double acting "Christmas tree" valve or some more modern double acting valve. Assuming you have true double acting cylinders which allow for oil to go through the rod side port it might be less headache and more streamlined to add a double acting valve. An aftermarket valve could go to the left or right of the steering wheel or even to the side of the seat to compliment your hand abilities. I have no problem putting both hands to work while operating a tractor but some of us favor one side or the other. As said assess oil needed to insure you can fully raise the loader or at least to a height you need to be practical. You may still need additional tank capacity. For operator safety pressurized hydraulic lines near the seat should be shielded in the event a pin hole leak shoots oil under pressure at the operator. A pretty good design would be to mimick the original Lift-all set up with the valve near the Lift-all housing with a rod working the valve running back towards the operator.

 

[TimD in MN]

NY 986 I had thought of the double acting valves for the loader but need to fugure out how to properly install it on the tractor for this loader. The operation of the cylinders are the question I have. With the double acting valve the cylinders would not have the fluid return to the pump as it is now, and are the cylinders set up to have pressure going to the return side to lower the loader vs. gravity. Information on the New Idea loaders are not readily available, from what I have found on the internet, and how they are connected to other makes of tractors. AGCO parts book does call the cylinders low pressure double acting. I might each out to AGCO about that.

 

[NY 986]

NY 986 I had thought of the double acting valves for the loader but need to fugure out how to properly install it on the tractor for this loader. The operation of the cylinders are the question I have. With the double acting valve the cylinders would not have the fluid return to the pump as it is now, and are the cylinders set up to have pressure going to the return side to lower the loader vs. gravity. Information on the New Idea loaders are not readily available, from what I have found on the internet, and how they are connected to other makes of tractors. AGCO parts book does call the cylinders low pressure double acting. I might each out to AGCO about that.

If you buy a new valve the box will contain instructions as to how to plumb the cylinder(s) to the valve and the valve to the (pressurized delivery and simple dump return) system. Your loader should have two identical cylinders versus a master and a slave cylinder making installation simple. Some fabrication will be needed to provide a mounting point to the tractor but the modern valve is more preferable than using the original "Christmas tree" valve at least in my opinion. As said above some caution needs to be used in terms of mounting pressurized lines near to the operator. For the purpose of dealing with a supplier your M's hydraulic system is open center.

 

[BarnyardEngineering]

Nobody currently at AGCO will have a clue about something built 60-odd years ago, unfortunately.

So you're not using the rod on the side of the tractor to lift and lower the loader? It has its own control valve? The way those valves work is there is an IN which is pressure from the pump, and OUT which is the return, then two "work ports" which connect to the extend and retract ports on the cylinder(s). The valve is what controls which port on the loader is connected to pressure, and which to return.

Most likely your problem is you simply overfilled the reservoir and it's venting the excess. There are only two ways fluid could be pushed out the fill pipe, air or more fluid.

 

[miangus]

Try increasing the height of the vent/filler tube.

 

[TimD in MN]

Thanks for the info BarnyardEngineering and miangus. I just got a replacement dipstick from Stieners so I will check the fluid level with that and see what happens. Still trying to decide if I should move the line from the bottom of the bellypump to the fill side by extending the fill pipe. I'll get the fluid level checked first and see what happens.

 

[SinkholeRoad]

I do not recommend moving the return line from the bottom drain to the fill. It will cause the fluid to foam. The reason the line is routed to the drain is to force the return fluid into the reservoir fluid with no air present to aspirate. If you route the return fluid into the fill tube it will aspirate with the air in the fill pipe and cause it to foam up so badly that you can’t make a fill tube tall enough to stop it.

Most likely the system is under filled and the aspiration is caused by not enough fluid present in the reservoir to dampen the return pressure.

 

[TimD in MN]

After several weekends away from getting any work done on the tractor, I finally got some work done this weekend. The new dipstick I got does show the belly pump oil level is overfilled (depending on how accurate the aftermarket dipstick is). I will try to remove some of the fluid and see is that may solve the issue. I am also going to look for a storage tank at a local tractor salvage and parts place near where I work. They may have one on another loader I could make work.