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MF 99 Loader on a MF 35 Utility Losing Lifting Power

G

gregrweiss

New User
I inherited a 1963 Massey Ferguson 35 Utility with a MF 99 front end loader on it. The loader seems to be losing lifting power so I'm guessing it's either the hydraulic pump or the control valve.

According to the owner's manual, the MF 99 Loader has a lifting capacity of 2,300 lbs half height and 1,500 lbs at full height. Right now it's struggling to lift 850 lbs square bales at half height. The dump piston seems to have more power than the two lift cylinders so my first guess is the control valve either needs to be rebuilt or replaced.

I've replaced the hydraulic fluid and cleaned the fluid filter in the pump without any noticeable improvement.

Does anyone know if there is a kit available to rebuild the control valve? Likewise, does anyone know if there is a kit to rebuild the hydraulic pump? Any other suggestions are greatly appreciated.

Thanks!
 
(quoted from post at 17:08:02 04/18/17) I inherited a 1963 Massey Ferguson 35 Utility with a MF 99 front end loader on it. The loader seems to be losing lifting power so I'm guessing it's either the hydraulic pump or the control valve.

According to the owner's manual, the MF 99 Loader has a lifting capacity of 2,300 lbs half height and 1,500 lbs at full height. Right now it's struggling to lift 850 lbs square bales at half height. The dump piston seems to have more power than the two lift cylinders so my first guess is the control valve either needs to be rebuilt or replaced.

I've replaced the hydraulic fluid and cleaned the fluid filter in the pump without any noticeable improvement.

Does anyone know if there is a kit available to rebuild the control valve? Likewise, does anyone know if there is a kit to rebuild the hydraulic pump? Any other suggestions are greatly appreciated.

Thanks!
Click to expand...

Just curious, do you have single or double acting lift cylinders? I've got a '64 Utility, so I take interest in all the variations. (Mine has a 99 loader with DA lift cylinders)

As for losing lift capacity, if you've already changed the fluid and cleaned the filter, I'd say your next step is to check your pressure. From memory it should pump 2150psi, and that's where the relief valve should be set. If you're getting the correct pressure then the pump is likely still good.

If you're not getting that pressure, you can shim the relief valve back up to spec. I'll have a factory manual tomorrow if you need pics of how to do that. If you still don't generate the pressure you need, the pump may be at fault.

Do the spool valves leak? Unfortunately, the factory setup (likely Aico) is not rebuildable. You'd be best off replacing with a set of Prince valves with a 20gpm flow rate from surplus center.

Hydraulic pump is an SAE type A, factory is 9.4gpm, but you could put a bit higher flow pump on. Just don't go crazy. Hope that helps!

PS- post up some pics of your machine if you can!
 
Thank you shaeff for the information!

To answer your question, my MF99 loader has single action lift cylinders. The owners manual I have is for the MF 99, 101, and 201. According to it, at least in 1963, the MF99 had single action lift cylinders with a single dual action dump cylinder. The MF101 had dual action lift cylinders with a single dual action dump cylinder. The MF201 had dual action lift cylinders with two dual action dump cylinders.

You are also correct on the pressure. According to the user's manual, the specs for the pump are 9.4 GMP at 2,000 RPM at 2,150 PSI.

The user manual does have a description of how to measure the pressure at the control valve. It also has instruction on how to adjust the pressure. My questions are:

(1) Where can I get a pressure gauge to test the pressure?
(2) When testing the pressure at the control valve, am I reading the pressure going into the control valve (pump pressure) or pressure coming out of the control valve?
(3) If I need to adjust the pressure, where can I get the shims? In the picture, they look like washers but the instructions say
One .010 shim should increase or decrease the pressure approximately 25 PSI.
Click to expand...
So I'm guessing the shims measurements are pretty exacting.

Again, thank you for the help! greatly appreciated
 
(quoted from post at 01:38:22 04/19/17) Thank you shaeff for the information!

To answer your question, my MF99 loader has single action lift cylinders. The owners manual I have is for the MF 99, 101, and 201. According to it, at least in 1963, the MF99 had single action lift cylinders with a single dual action dump cylinder. The MF101 had dual action lift cylinders with a single dual action dump cylinder. The MF201 had dual action lift cylinders with two dual action dump cylinders.

You are also correct on the pressure. According to the user's manual, the specs for the pump are 9.4 GMP at 2,000 RPM at 2,150 PSI.

The user manual does have a description of how to measure the pressure at the control valve. It also has instruction on how to adjust the pressure. My questions are:

(1) Where can I get a pressure gauge to test the pressure?
(2) When testing the pressure at the control valve, am I reading the pressure going into the control valve (pump pressure) or pressure coming out of the control valve?
(3) If I need to adjust the pressure, where can I get the shims? In the picture, they look like washers but the instructions say
One .010 shim should increase or decrease the pressure approximately 25 PSI.
Click to expand...
So I'm guessing the shims measurements are pretty exacting.

Again, thank you for the help! greatly appreciated
Click to expand...

You're welcome!

The reason I asked about your lift cylinders, is that I also have a 35 Utility with a 99 loader, but someone put double acting lift cylinders on mine. I have a manual that's very close to what you describe, but it shows the 99, 101, and 102 loaders.

99= SA lift, and one DA dump cylinder
101= DA LIFT, and one DA dump cylinder
102= DA lift, and two DA dump cylinders

Weird! The main difference is your calls it a 201, mine calls it a 102 loader.

I would first check pressure before the valves, that's your pump pressure. If that specs out ok, then move the gauge to the lift cylinder circuit AFTER the valves. Operate the lift circuit and verify pressure.

1) You can get a pressure gauge and the fittings you need to hook it up from surpluscenter.com. I'm actually going to be ordering a setup within the next few weeks to check/verify my own machine.

2) both, you want to check pressure before the valve to verify pump is ok, and after to verify the valves are ok

3) I'd guess that you can get some small washers, find some as close to the factory shim size as possible. Everyone's relief spring will fade at a different rate, the manual even states that. I'd just shim it out until you get proper pressure. If you get a shim that's a touch thicker, just make note of how much it raises the pressure so you can extrapolate how many more shims you will or won't need.

Good luck with it!
 
Forum won't let me edit:

Just looked in the manual, it says just hook up the gauge to the pressure line before the spool valves, run either the dump or lift cylinders to the end of their reach until the pressure relief valve opens. Check the pressure at that point with the relief squealing.

I would assume that if the valves are in question that the gauge could plumb the gauge in after the valves to see if you're losing pressure there.
 
(quoted from post at 05:25:41 04/19/17)
(quoted from post at 01:38:22 04/19/17) You're welcome!

The reason I asked about your lift cylinders, is that I also have a 35 Utility with a 99 loader, but someone put double acting lift cylinders on mine. I have a manual that's very close to what you describe, but it shows the 99, 101, and 102 loaders.

99= SA lift, and one DA dump cylinder
101= DA LIFT, and one DA dump cylinder
102= DA lift, and two DA dump cylinders

Weird! The main difference is your calls it a 201, mine calls it a 102 loader.

I would first check pressure before the valves, that's your pump pressure. If that specs out ok, then move the gauge to the lift cylinder circuit AFTER the valves. Operate the lift circuit and verify pressure.

1) You can get a pressure gauge and the fittings you need to hook it up from surpluscenter.com. I'm actually going to be ordering a setup within the next few weeks to check/verify my own machine.

2) both, you want to check pressure before the valve to verify pump is ok, and after to verify the valves are ok

3) I'd guess that you can get some small washers, find some as close to the factory shim size as possible. Everyone's relief spring will fade at a different rate, the manual even states that. I'd just shim it out until you get proper pressure. If you get a shim that's a touch thicker, just make note of how much it raises the pressure so you can extrapolate how many more shims you will or won't need.

Good luck with it!
Click to expand...

Thanks again shaeff. And you are correct. I was going off memory but looked at the user's manual and it is for a 99, 101, and 102 loader. I guess my dyslexia finally caught up with me.

I'll be figuring out what connections I need to do the test and will update this thread when I do.

Thanks and good luck to you as well.
Click to expand...
 

No problem. Hooking a gauge in should be pretty easy. Most difficult part will be finding the proper "T" to fit in before the spool valves. At least that's my guess. I haven't searched for what size the hydraulic lines are, but the manual says "SAE Standard."

Chances are that after 50yrs both of our relief valves likely are out of spec.
 
Another thing we should both be thinking about: one or more of our hydraulic cylinders may be bypassing or leaking. Just another scenario to consider.
 
(quoted from post at 08:29:07 04/21/17) Another thing we should both be thinking about: one or more of our hydraulic cylinders may be bypassing or leaking. Just another scenario to consider.
Click to expand...

Thanks for the suggestion. I haven't noticed any external leaks but it may have an internal leak.
 

Okay, it's taken me a while and I've concluded that the hydraulic control valve needs to be replaced. I've been working with Surplus Center to build a custom control valve and they asked a good question that I didn't know the answer to.

According to the manual, the loader uses a Cessna gear-type constant flow pump. The pump's output is 9.4 GPM at 2,000 RPM at 2,150 PSI.

The control valve is a two spool valve with a single acting lift spool and a double acting dump spool. The valve capacity is 20 GPM at 2,150 PSI.

The question I was asked, which I couldn't answer, was why I needed a 20 GPM control valve when the pump is rated at 9.4 GPM? Does anyone know why a 20 GPM control valve is paired with a 9.4 GPM pump?

Thank you in advance!
 
If you put a spool valve that flows 7 gpm the valve would be a restriction. It's normal to use spool valves with a lot higher gpm capacity than the pump puts out, it won't hurt anything.
 

I know this an old post buy im having the same issue was the shop able to build you a new valve? if so could you let me know the name and what they charged you?
 
(quoted from post at 16:04:11 10/09/22)
I know this an old post buy im having the same issue was the shop able to build you a new valve? if so could you let me know the name and what they charged you?
Click to expand...

I doubt it's rebuild-able. You should do some trouble shooting. It's possible one of the cylinders is leaking internally or the pump is tired. Start with pressure to the valve. Do dump and lift act the same way?
 

Welcome to the Forums.

Please start a new post of your own. As you are new to the site you likely wouldn t know the following. This site uses two different views, Classic and Modern. Anyone using the Modern View sees the old post, your new post, and any responses to your post together as seen on most forums. Those using the Classic View only see your post as a RE to the original post, which does not include the original post, as after a post is a few pages old in Classic replies do not link to it. Because of this for anyone using Classic view there is no background to what you are asking and it may get you off the wall replies to your post. Then any replies, like this one, to your post will generally show as random REs in Classic, with no connection to the original or your post.

Start a new post of your own, give all the pertinent info about your machine and the problem, then it can be responded to and stay grouped together in both views. Single or double acting cylinders is important info.

For the most part valves are not rebuildable as the spools and body are sealed by the metal-to-metal fit of the parts, they can t be interchanged as a general rule. At most you might have a couple O-rings or seals on the spools to control external leakage. You will need to find a valve for single acting lift cylinders (with a float position) and double acting bucket cylinders, if that is the way your loader is set up. Those are not as common as double acting on both functions.
 
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