MF135 Hydraulic Pump?

[tessiers]

I have a 1970 MF135 Perkins diesel. Last year my hydraulic pressure was at about 300 psi give or take, I bought a rebuilt pump and installed it and everything worked great PSI over 2000. Over the course of the year, maybe 200 hrs. the pressure has slowly dropped to 500 psi again. Is there anything else could be causing my troubles? I have checked the filter several times. Pressure relief?

 

[SIMassey]

I have a 1970 MF135 Perkins diesel. Last year my hydraulic pressure was at about 300 psi give or take, I bought a rebuilt pump and installed it and everything worked great PSI over 2000. Over the course of the year, maybe 200 hrs. the pressure has slowly dropped to 500 psi again. Is there anything else could be causing my troubles? I have checked the filter several times. Pressure relief?

Stand pipe o-rings leaking or cracked standpoint?

Is this pressure at a remote or at the top cover?

Is the three point unable to lift the implements it used to?

If you are measuring the pressure while lifting the three point,the rings in the lift cylinder could be worn.

 

[tessiers]

Pressure I'm measuring is at the rear remote, I haven't had the 3 point arms on in a long time, I could try them I guess. I use a 2x10 cylinder to lift the mower conditioner head.

 

[SIMassey]

Pressure I'm measuring is at the rear remote, I haven't had the 3 point arms on in a long time, I could try them I guess. I use a 2x10 cylinder to lift the mower conditioner head.

It sure doesn't make sense. You replaced the pump and had good pressure. Now it's acting the same. My first thought would be the pump again but I wonder if it is something internal like the relief valve. I hope it's something simple and cheap for your sake. Do you have a two spool Massey valve on top the lift cover running a double acting cylinder on the mower conditioner? If you are running a single acting cylinder using a single remote and operating it with the position lever is why I suggested it could be the three point lift cylinder. It will be interesting what you find.

Good luck

 

[tessiers]

It has a selector valve on the lift cover, 1 position allows the 3 point to work, the other feeds a remote valve mounted on the fender. I called the hydraulic shop I use, he says bad pump, they don't have much trouble with returns but he said it is possible. He said they will go good for it, there is no way to test it out of the tractor, so they will tear it down and see whats wrong.

 

[SIMassey]

It has a selector valve on the lift cover, 1 position allows the 3 point to work, the other feeds a remote valve mounted on the fender. I called the hydraulic shop I use, he says bad pump, they don't have much trouble with returns but he said it is possible. He said they will go good for it, there is no way to test it out of the tractor, so they will tear it down and see whats wrong.

With the selector valve on it rules out the possibility of the three point cylinder issue. Massey hydraulics are a bit odd and can be hooked up different ways so understanding your hookups will help diagnose the problem.

Yep, I'd bet on the pump now, Unless you've haven't had a side cover off ruling out the standpipe o-rings. You can still hope it's something simple. Hurts since its getting busy time for a tractor to be down.