Question on Hydraulics Set-up

[bmacd11]

I've been working on a 1967 MF 135, with the constant pumping feature, that I bought last summer. To put it mildly, it is a fixer upper, or more like a basket case actually, but I needed a hobby. This is the second MF 135 that I've worked on. My brother had one which was also a basket case and we basically rebuilt it. That was a great experience and I learned a lot.
Back to mine now; I took the lift cover off and went through all the adjustments since the hydraulics were kind of squirrelly when I bought it. The lift arms dropped as soon as the tractor was shutdown and the 3 pt controls were way out of whack. The hydraulic fluid was mostly water which I thought was a big part of the problem. I replaced the lift piston for one with the teflon ring over an O ring. I made adjustments using the MF shop manual; of course, I had to improvise on the special tools. The 3 pt works much better except for some very minor chatter while raising. It was more noticeable before I changed the oil but next time I have the lift cover off, I'll change the valves too. The new lift piston works much better and holds the load up after shutdown but it still falls over time (about an hour with a load on it). The cylinder walls were pretty scored up so I expect that is the problem. I did hone it a bit before re-installing but was afraid go too far with it so there were still noticeable scratches on the side walls when I put it back together. I have a new cylinder on order now.
So, now to my question: when I start the tractor with the position control fully down and the draft control fully up, the lift arms raise slightly to the level position. I don't think this is correct since someone could get hurt like this. The only way to stop this from happening is to start with the draft control fully down. Even then, when I raise the draft control lever to give me access to the position control function, the arms raise to level. Any ideas on where I went wrong on the adjustments? I expect the issue is the draft control adjustments but I don't really know why. The tension on the vertical lever was 6 pounds and I changed it to 3 pounds as per the manual. I don't know if I should put more tension or less on the draft adjustment. The manuals are good for telling you what to do but not for when something weird happens like this. One other point is that I really couldn't get 3 pounds on the position control set-up as called for. The adjusting screw is all the way in and there's maybe 2 pounds on the vertical lever; something wrong with the position lever that would cause the issue? Having said that, the position control lever works perfectly when running.
Appreciate your thoughts on my issue. Thanks in advance.

 

[lugnuts2030]

As far as 3pt lowering after shut down: They were made to leak down when engine is shut down..............
I have been running old Masseys since 1970 and havent had any trouble. As long as they go up and down I won't mmess with them. But I havent bought a problem one either.

 

[bmacd11]

Probably good advice. Thanks.

 

[Dieseltech]

The lift cover POSITION linkage is still not set right. You should be able to raise/lower arms with the position lever, and stop arms part way anywhere on the quadrant
with the position lever.

 

[bmacd11]

Yes, it does that. Position control works well except that the draft control wants to raise the arms a couple inches before I do anything with the position control. Position control won't put the arms down lower than level because the draft control hangs it up. If I put draft control all the way down, with Position control down, then the arms fall the last couple inches.

 

[DavidP,South Wales]

I would agree with Dieseltech. The relationship between the Position Control lever, the 3-point linkage and the pump control valve is out of adjustment. I suspect that your lift cover adjustments are not accurate enough. I presume that you are referring to the knurled screw when you mention that the “adjusting screw is right in”. When you lower the PC lever the pump control valve will be slightly into the pumping position. Screwing the knurled screw out a little at a time will move the pump towards the neutral position. You should be able to reach a position where the 3-point will fall and stay there. If you can’t achieve this by adjusting the screw you internal adjustments are out. Just one vital check to make. With the PC lever fully raised to the stop you MUST be able to lift the lower links a further 1 1/2” or so to ensure that the system does not lock up. Carry out this check cautiously to ensure that it does not lock up too early. Adjust the stop if necessary. Nothing can be taken for granted if your other adjustments are out.
DavidP, South Wales

 

[DavidP,South Wales]

As was asked by one of the instructors at the MF Training School in the UK in 1974 “why do you want them to stay up?”
DavidP, South Wales

 

[Dieseltech]

It's acting that way because the POSITION controls are not set right. With draft lever fully up, and position won't go all the way down is POSITION side adjustment, NOT
the draft side..

 

[bmacd11]

Ok, ok, I don't care if they don't stay up anymore

I'm in the process of removing the lift cover again to re-do the settings. If at first you don't succeed....

BTW, it does have the extra play required at the top end....I saw the tractor split story.

I'll let you know how it turns out and revert with any questions. It may be a couple of weeks.

Thanks for your input.

 

[bmacd11]

I removed the lift cover again and re-did all the adjustments. Both draft and position adjustments were out very slightly. Put the cover back on and the same thing happened; with PC down, I raise the draft control all the way up. This causes the lift arms to raise 1&1/4 inch which translates to about 4 inches at the lower links. Is it possible that this is normal? Doesn't seem right to me but all internal adjustments are correct.

 

[bmacd11]

A revelation: while still investigating, I removed the position control lever slide tensioner and moved the PC lever all the way down, and past the stop (about 3/4 inches further that the PC lever channel would normally allow). The lift arms dropped to the full down position. The lift arms now raise and lower through their full range and specifically go all the way down when I go past the tensioner channel. With the lift cover off and still upright, you can see the lift cam moving downward another 1/8 inch when going past the tensioner channel and past the stop. Same thing with the lift cover upside down except that the lift cam moves upward relatively. So, I believe that the lift cam is not moving to its full down travel when the PC lever tensioner and stop are in their normal position. I've tried to adjust everything to make the lift cam move that extra 1/8 inch with the PC lever in its normal physical travel channel to no avail. So, what is the issue with the position cam travel? Could it be that the cam or its rollers are worn to the point where it can't get that extra 1/8 inch which in turn won't let the lift arms fall all the way down? The tractor does have a lot of hours on it.

 

[bmacd11]

A solution?? I was researching the issue on the internet last night and came across a technical article by Agriline Diesel in South Africa. http://www.agriline.co.za/technical/technical/hyd_maintenance.html
They run a tractor shop and specialize in Massey Ferguson and Ford. They say in the article that due to wear over the years, things will have to be adjusted to reduce stress on the hydraulic system. One of the adjustments suggested was to move the adjustable inner quadrant plate (position plate) toward the rear of the tractor. This adjustment was meant for setting lift arm free play at the top, but I thought why wouldn't it work to adjust the bottom setting as well. Well, I did that today and wow; problem solved. When I start the tractor with draft control up and PC down, the lift arms don't move. The lift arms respond to PC inputs through the entire range and stop about 1/4 inch from the top (measured at the ram shaft).
I think this is a great solution to my problem specifically and if sanctioned by the experienced forum, may be helpful for others out there.

 

[bmacd11]

P.S. And you're correct in that it WAS a position control issue and draft control had nothing to do with it.
BTW, I put a 'minor' rebuild kit in the pump (chambers, valves, pistons and blocks) and it works very well now. No jittering on the lift arms at all. The old parts were pretty worn.