MF 165 Power Steering Keeps Going Out

I have a MF 165 that I have put three new pumps on and they keep going out. Luckily they have a one year warranty. They only last about 8 months or so with very little use on tractor. I replaced the linkages on the cylinder because they were wore out but didn't seem to help. The cylinder also has a small leak but I always made sure to keep the pump full of universal hydraulic fluid. The steering has play in it. I noticed when turning the steering wheel back and forth through the movement of the free play the cylinder and steering arms move. I posted a video link below to show you what I'm talking about. I'm not sure if that is causing the cylinder to actuate the pump to much causing premature failure. Thanks for any help!
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If the pumps are getting REALLY HOT quick check the pressure line from the pump to the cylinder. I had a 175 years ago that the line was bad with a small hole rubbed in the side, and when the owner tried brazing it he got too much rod inside the line, almost closing it completely off so little oil could get through, eventually burning up the pump. When I replaced the pump and first started the engine I could hear the relief valve blowing right away. Installed a new line corrected the problem. Something is wrong to have that many pumps die that fast..

looks like too much play in upper to lower arm. tighten screws on front and back of lower arm to remove play

Hello, having looked at your video several times your problem may be down to excessive movement of the spool valve. Clearly you have significant wear in the bushes and/or main vertical shaft. You will not have fully efficient PAS until these bushes are replaced and reamed to the correct size for the shaft. The movement of the steering wheel appears to operate the spool only in one direction (pulling it out). It is difficult to see if there is any movement to push the spool in which will activate PAS in the opposite direction. I suspect that having too much 'pull' on the spool is causing it to travel beyond its range of operation and is effectively reducing or blocking the flow of oil to the cylinder. If this is the case this may be why your pumps are wearing prematurely. It is ESSENTIAL that all play is taken out of the cylinder linkage and then the spool adjustment carried out correctly so that pull and push on the spool have the same travel when turning the steering wheel left and right. Play can be removed by drilling out and fitting larger pins for example, making shims wherever required, replacing and reaming bushes. Time and money spent in this will be well rewarded with an efficient PAS system.
DavidP, South Wales

OK I think I will try to replace the bushings in the lower and upper arms. Hopefully this isn"t too hard of a job. I replaced the linkages and installed a new pin. I haven"t really looked real close to see if there is still some movement with the new pin. Also when I tried adjusting the stop screws on steering arm The steering wheel turned on its on. What is the best way to adjust these? Thanks for the help.

Hello Josh,
This exact type of steering is found on North American tractors only to the best of my knowledge. The type that we have in the UK and Europe is very similar in principle but constructed differently. I would adjust it as follows after taking out all of the wear/play in the vertical shaft bushes, end float in the cylinder rod and particularly up and down movement where the rod is attached to the axle casting and anywhere else that will cause loss of actuation on the spool.
1/ Slacken both stop screws say 2 to 3 turns so that both are clear of the steering arm.
2/ Ensure that the spool is in the central (neutral position).
3/ Connect the link rod.
4/ Screw in each stop screw until they just makes contact with the arm on each side.
5/ Unscrew each one one turn at a time and have an assistant turn the steering wheel in the 'play'.
6/ Observe the amount of push and pull movement on the spool. It should be around 1/8" (3mm) max in each direction.
If you have more movement in one direction than the other you are probably losing movement due to play/wear still in the system. This should be rectified as it will result in far better assistance in one direction than the other. Positive equal movement is essential to give the same amount of activation to the hydraulic system.
You may also need to adjust the steering box on the 'high spot' to ensure that precise steering movement is translated into the initial actuation for the spool.
Let us know how you get on.

David, when reaming bushings, how much larger than the shaft should the bushing be reamed to? I'm going to have to do this to my 165 soon as well and I've never replaced and reamed a bushing before.