856 MCV Issues Still

I posted on here a while back about some MCV issues. I have checked the pressure, and it is a little over 1500 at PTO RPM. I don't have a flow rater. All the problems went away until last night. The power steering worked perfect steering to the left, but not steering to the right. Also, it did not shift a couple of times correctly from low range to high on the TA. When I shifted, it would loose power to the wheels for an instant before high range would lock up. The brakes appeared to be fine. Does this sound like a pump problem or a valve problem? I don't really want to throw money at it until it is fixed and I don't have enough experience on the big tractors to know which way to go. Thanks for any help.

And where did you check pressure at???? Is the spool valve going all the way up and all the way down against the snap ring ??? . It sounds to me that you are having a sticking valve problem IF you checked pressure at the bottom plug then the pressure there should have been around 230-240 . not 1500 . Then again if you checked pressure at the steering orface plug then you should have 1800at pto speed when holding the steering wheel to the stops .It could be a sticking flow control valve. It could be that all the springs in the MCV are weak . Do you have and I T manual ?? if not get one and set of dial calipers and read thru it and then remove the MCv and take it apart and check all the spring free length's against the book . Becareful not to loose the sump check plug and spring located in the lower right hand side behind the MCv valve body when you remove it and make sure that you use the same thickness gskt to remount . If you were close to me i would be more then willing to help ya. But wright now your would have to take a number as my phone has not stopped ringing and i am working on three tractors now . And here i thought that retirement was going to be nice. Just go play in the dirt and set back

Well, that points me to the problem. For some reason I though it should be 1500 pounds. That is measured at the port shown in the IT manual for the main pressure relief valve. That would be the lowest plug on the rear side of the MCV (I think). I will check the spings, and if that is not it then I guess it is the pump. I checked on the price of the pressure relief about a month ago. They said it was $145. Does that sound right? Where would you suggest I get the parts from CIH (where I normally go) or somewhere else. Thanks for the help TV.

As long as the pressure relief valve is opening, it will only affect the steering. Its purpose is to limit the maximum pressure to the steering. The steering system gets priority on the MCV pump flow but unless the steering is held against the stops, the flow bypasses the relief valve and pressure is controlled by the regulator valve in the MCV assembly. Excess flow from the regulator valve is routed to the TA lube and again regulated by the lube pressure regulator valve.

Since your problem is not constant you may want to check to see if the orifice is loose in the MCV valve. It is accessed through the port in the rear of the MCV that has a 5/8 inch hex plug. An orifice that is out of place can cause the flow to vary in the MCV circuits.

I don't know about the 856 but I'm not sure I'd replace the relief valve first. However on my 2606 which I'm still having steering problems, the relief valve was always open and I had no pressure. When I pulled it, there was a small piece of metal that looked like the end of a broken spring holding the ball open. In hindsight I should have used a strong magnet to catch the metal piece because when I put it in the vise to depress the ball, the metal piece fell back inside the relief valve. It still appears to be working but I suppose that metal piece could still get stuck again.

I didn't pay the 80 bucks for a new one. A used one should be available at any of the salvage yards.