MF 235 Rear Lift Issue & Power Steering

   / MF 235 Rear Lift Issue & Power Steering #1  

wslove

New member
Joined
Nov 3, 2011
Messages
4
Tractor
Massey Ferguson 235
1975 Model 235 diesel tractor with < 700 hrs, assuming hour meter is correct (still tracks time), was my dad's and still runs just fine, but has two mechanical issues that I'm currently aware of:

1) Power steering is completely inoperable. No "odd" noises, but there is significant leakage where the right pitman arm connects to the steering box. I've ordered new seals, new power steering pump filter (and gasket), but is there anything else I need to look into that might be the cause?

2) Bigger issue is the rear hydraulics. They've been SUPER slow (both up and down) for awhile now. After trying to lift a medium sized tree that fell on a car last year, and having to "help it" up, I found myself saying "I *know* this thing could lift more when I was kid" We cleaned up hundreds of downed trees with just this tractor, a boom pole, and a chainsaw after Hugo came through in '89. The tree I was trying to move recently was small in comparison.

This got me to experimenting. In wanting to "reboot" the old farm, I've purchased some new equipment - one of which is a set of 3pt pallet forks. Using a pallet I knew the approximate weight of (~800lbs), it wouldn't budge it. Further experimentation needed - I ordered a 6klb capacity crane scale off Amazon and did a few tests. With a standard boom pole, it was only able to max out around 250 lbs of lift at the tip. With the pallet forks, a little better with ~350 lbs at the end (48" forks) and ~700 lbs at the closest point to the tractor. Which leads me to the "weird" part. When I put a standard drawbar in the 3pt arms (no top link attachment), it was able to lift >2,000 lbs before front tires left the ground. All testing was done at idle and 540 PTO RPMs, with draft control in multiple positions, the drop speed control in both positions as well.

Long question short, is there something I should be looking at that may be causing the slowness and completely anemic lifting capacity when there's something connected to the top link? I've changed out the hydraulic oil and filter.
 
   / MF 235 Rear Lift Issue & Power Steering #2  
"Something I should be looking at?" Probably so, but some knowledge and experience on your part (or whoever is working on it) would go a long way. You changed hydraulic oil and filter. What filter? You need to understand that just because it's a 235 doesn't mean all 235 tractors are identical. MOST 200 series tractors had a hydraulic pump suction screen on the pump inlet manifold. It's access (after draining the fluid) by removing a small, tin , three bolt cover on the bottom of the rear main housing. It's just a screen, not a filter.

If the lift arms will lift a load without the top link in play something in the draft control spring assembly could be part of the problem. Massey used that same top link sensing system for draft control for years on dozens of different models, in one form or another. Here a service manual describing the system, exploded parts views, and assembly/adjustment procedures is a must have. With the top link disconnected, if you grab the yoke where the top link pin would go, push and pull on that as hard as you can. Can you feel or see any movement on any of those parts? If so, something is too loose in that area and it will adversely affect the operation of the lift arms under load. Another thing you can check easily enough (provided you tractor doesn't have pressure control) is the standpipe O rings. They have been known to fail over time and can affect lift capacity. Although the top link involvement in this mostly rules that out. The standpipe is under the little 2" X 3" cap bolted on top of the lift housing in the right front corner. Two 7/16" bolts and it comes off.

As for the steering, if it has pitman arms it's a problematic system to begin with. The leaks you mentioned are likely not part of why it doesn't work. Does it work any better when the pump is full of fluid and the fluid is relatively cool (or cold)? Honestly, that system is well known for failures in one way or another, and parts are not easy to get.
 
   / MF 235 Rear Lift Issue & Power Steering #3  
You have worn internal draft control linkages. Common problem . You will need further advice on how to deal with this.
I had the same problem on my MF135. I used a chain top link to the diff housing pin (3 ears) (pin has a hinge point in the middle ear as a ridgid pin is to long to fit between the ear and mudguard) just below the top link connection.
 

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