MF 135 - Can the PSI be adjusted on the Power Steering Pump?

[p3210]

Hi Folks
I acquired an MF135 (1971?). The original power steering pump failed. I replaced it with a genuine MF power steering pump (part 773126v92) from a Massey Ferguson autherized repair shop.

Question - Is there a mechanism on the pump to make it possible to lower the PSI on this pump? Can I adjust a nut or screw on the relief valve?

Apparently this new pump puts out 1500 PSI. The original pump was rated at 1175 PSI.
I'm having problems with seals blowing out (last one was associated with the rod in the power steering cylinder). I have read about installing a bypass hose in the steering column to releave pressure; which I might do. But wondering if I can lower the pressure at the pump.

Any thoughts greatly appreciated.

Thansk!
Phil

 

[pmsmechanic]

I would be tempted to ask the shop that rebuilt the pump first.

 

[p3210]

Thanks - Yep, I asked the shop to take a look at the old pump and rebuild.... they inspected the old pumt, pointed out the worn metal and said it was too far gone.

 

[GeorgiaRebel]

I'm with pmsmechanic. I would ask the shop that did the work if there is a way to lower the pressure.

I have a 135 and have always had problems with leaks. I have done several seal replacements and leaks persist. Others have reported similar experiences. I am resigned to just adding more fluid.

 

[pmsmechanic]

There should be a threaded plug on the side of the power steering pump. If you remove the plug there should be a spring inside pushing on a sliding piece that fits precisely in the bore of the hole. There might be some shims by the spring on either end. If you remove the shims or install a spring with less tension the pressure should go down as the sliding plug and spring regulates the pressure of the hydraulic system.

If you decide to lower the pressure be very careful to install everything back exactly the way you removed it. In fact I wouldn't remove the sliding plug at all. All you need to work with is the spring and shims.

Good Luck!

Edited to add that I might have a service manual for a 135 at home. When I get back home I'll have a look and see if there's a picture of the power steering pump. If it looks like I forgot to look and mention something on this thread, I have. Please don't be shy about reminding me in a couple of days.

 

[p3210]

I'm with pmsmechanic. I would ask the shop that did the work if there is a way to lower the pressure.

I have a 135 and have always had problems with leaks. I have done several seal replacements and leaks persist. Others have reported similar experiences. I am resigned to just adding more fluid.

Thanks GeorgiaRebel - Unfortunately the leak more of a constant flow. I wish it was a slow leak that I could just refill the pump at the end of the day....

 

[p3210]

There should be a threaded plug on the side of the power steering pump. If you remove the plug there should be a spring inside pushing on a sliding piece that fits precisely in the bore of the hole. There might be some shims by the spring on either end. If you remove the shims or install a spring with less tension the pressure should go down as the sliding plug and spring regulates the pressure of the hydraulic system.

If you decide to lower the pressure be very careful to install everything back exactly the way you removed it. In fact I wouldn't remove the sliding plug at all. All you need to work with is the spring and shims.

Good Luck!

Edited to add that I might have a service manual for a 135 at home. When I get back home I'll have a look and see if there's a picture of the power steering pump. If it looks like I forgot to look and mention something on this thread, I have. Please don't be shy about reminding me in a couple of days.

Thanks pmsmechanic. There is a "relief valve" which sounds like the plug with spring you mentioned. I was hoping that the valve might be a way to lower the PSI.... I think I still have the original pump... I wonder if I can just change springs. Thanks again!