MF 135 Power steering issues

[jticknor]

Ok, I have a 74 (or 73?) MF 135 orchard. Diesel. A couple weeks ago I was tilling my garden and busted a power steering line on the left side from the piston to one of the fittings under the steering column. Had my hydraulics shop make me a new hose (actually just went ahead and replaced both on that side). Bled the system out, I used a pureguard "premium hydraulic fluid j20c and quatrol approved" that a local MF dealer sold me that I was of the understanding would be used for power steering.

Here is a link to the fluid: https://omnisp.sharepoint.com/sites...eguard/Technical Data Sheets/PDSs&p=true&ga=1

Cranked it up, used it to till my garden. Probably was on it an hour or so. No real problems, other than the steering being maybe a little stiffer than it used to. Got on it yesterday to use my box blade and now the steering is much more difficult. Basically when I turn my wheel smoothly, evenly, i get short jerky responses from the pistons, as in I move the steering wheel fairly fluidly from 12 to 3 oclock and i got no movement from the pistons, then an inch or so jerk, no movement then an inch or so jerk, if that makes any sense? Bled everything again, topped off the reservoir, no difference. Did i do something wrong or is this one of those situations where you fix one thing and something else breaks because of it? I'll try to add a video to see if that helps.

 

[FordnMassey]

Hi,
Does the power assistance fail at the same steering wheel positions each time you cycle through a fully left to fully right turn?
Can you view the fluid reservoir when the motor is running? If so, are there bubbles or foaming in the fluid?

 

[JWR]

It looks to me like (from the video) that you still have air bubbles in the fluid. A signif question is did you have any of these symptoms before the hose incident? If not, it almost has to be an air in the system issue in spite of you having bled it twice.

 

[jticknor]

Hi,
Does the power assistance fail at the same steering wheel positions each time you cycle through a fully left to fully right turn?
Can you view the fluid reservoir when the motor is running? If so, are there bubbles or foaming in the fluid?

It does not seem to be exactly the same spots but it’s kind of hard to tell. Seems to have more to do with how far I turn the steering wheel at a time? Like I can turn it may be 5 to 6 inches and then it’ll happen another 5 to 6 inches and then we’ll do it again. If I open the reservoir while the motor is running there is an awful lot of fluid tries to come out. I’ll try again here in a few. It does seem kind of foamy. But also seems odd I didn’t have those problems so much for a few hours of use afterwards.

 

[jticknor]

It looks to me like (from the video) that you still have air bubbles in the fluid. A signif question is did you have any of these symptoms before the hose incident? If not, it almost has to be an air in the system issue in spite of you having bled it twice.

I did not have those problems before I switched the hose. Before that it turned nice and smooth. But I also didn’t really have that problem so much for a couple hours afterwards.? What would I need to do to make sure I bleed the system all the way?

 

[JWR]

That is VERY strange. I'd be purely guessing at this point. If a hose or rubber part were "ballooning" that might explain it but those things burst instead of balloon. Since it was not happening before the hose incident it just about has to be air pockets somewhere in the circuit. I can think of nothing besides more extensive bleeding which it seems you already did. There's no mechanical anchor point loose or failed to be reconnected is there?

 

[FordnMassey]

Hi,

To check if the oil is foamy, try looking at the appearance after it has sat for a few hours compared to immediately after it's been running.

If it's foamy, read on.

I was also in this position of thinking "perhaps I haven't bled it enough". But these systems are invariably self bleeding by going full L to R 2-3 times. The pressures of course are high, so there's really no way for air hide. Continue to think it through, but if the oil is foaming, I am sure you will reach the conclusion that new air is being drawn into the system and that it's not just some air trapped somewhere.

I forgot to mention that when I had this issue the steering would also be power assisted intermittently after a start up (after several hours stationary). It would assist for around 5 seconds, then fail, and returning the wheel in the reverse direction there would be a burst of assistance before it failed. I think this is the unfoamed oil in the lines providing proper pressure, before foamed oil gets into the system.

When I resolved the inwards air leak, my system bled with two full turns each way and has worked fine since.

My suggestion is look hard at the pump intake side of the system and if the lines seem good, then the shaft seal inside the power steering pump is the issue.

Why would this arise after repair on a line? No idea, or dumb luck. My issue arose 6 hours after a filter and fluid change for the power steering, and my pump is remote to the reservoir so there's no mechanical reason. Was mine coincidence or due to the new fluid? No idea. Working fine on the same fluid now.

 

[JWR]

That is a great post by FordnMassey. Makes all kinds of sense.

 

[jticknor]

Hi,

To check if the oil is foamy, try looking at the appearance after it has sat for a few hours compared to immediately after it's been running.

If it's foamy, read on.

I was also in this position of thinking "perhaps I haven't bled it enough". But these systems are invariably self bleeding by going full L to R 2-3 times. The pressures of course are high, so there's really no way for air hide. Continue to think it through, but if the oil is foaming, I am sure you will reach the conclusion that new air is being drawn into the system and that it's not just some air trapped somewhere.

I forgot to mention that when I had this issue the steering would also be power assisted intermittently after a start up (after several hours stationary). It would assist for around 5 seconds, then fail, and returning the wheel in the reverse direction there would be a burst of assistance before it failed. I think this is the unfoamed oil in the lines providing proper pressure, before foamed oil gets into the system.

When I resolved the inwards air leak, my system bled with two full turns each way and has worked fine since.

My suggestion is look hard at the pump intake side of the system and if the lines seem good, then the shaft seal inside the power steering pump is the issue.

Why would this arise after repair on a line? No idea, or dumb luck. My issue arose 6 hours after a filter and fluid change for the power steering, and my pump is remote to the reservoir so there's no mechanical reason. Was mine coincidence or due to the new fluid? No idea. Working fine on the same fluid now.

If I'm getting air in somewhere, besides the seal, shouldn't I be seeing fluid finding its way out? I didn't mess with much in the system when I replaced those two lines, and those two lines don't show any signs of leaking. I did see mention somewhere that i could have gotten the lines crossed, but seems if that was the case the two sides would be fighting eachother and not moving much at all? I'll look at the foaminess situation again tomorrow but it does seem foamy. Wondering if the different pressure changes and whatever else involve could have blown that seal....although it did seem equally foamy when i orignally bled the lines and then used the machine for an hour or so with no real issues...

 

[JWR]

No, a small air leak on the inlet side of your pump would always be under suction (negative pressure) when running and no pressure when not running so you'd probably not see any fluid leakage. Besides, the air leaks, if they are there, are probably very tiny and not easy to find or see. Could have been that way for a while and just got worse wiggling things around during the incident.