Massey Ferguson hydraulic pump MK2 - fault finding
The MK2 hydraulic pump was fitted to the MF series 100 tractors, 135, 165, 175, 178, 188 etc.
Essentially when the hydraulic system fails for various reasons the only logical solution is to remove the pump & lift cover, overhaul both & reinstall. However in may cases farm and or other production needs overide this until shutdown time allows for full maintanance. Sometimes our budgets don't allow us to spend what we should on repairs. Spare parts cost, labour if it's your own does'nt.
Fault diagnostics & solutions
Before removing the hydraulic system for repairs always check the operation of the tractors PTO shaft. Tractors fitted with a dual clutch provide the drive to the hydraulics via the transmission through the PTO clutch plate. On occasion when an obstacle is hit through the PTO shaft, for instance when cutting grass the rivets are sheared on the plate, resulting in lack of power transmission from plate - through gearbox - to hydraulic pump. Test with a PTO driven implement attached. This problem is not that common however many a hydraulic system has been overhauled only to realise that the problem is pressure plate related.
Tractors fitted with a single clutch system will present both gear selection & no drive to hydraulics. Gear & drive problems being the most obvious.
The easiest diagnostics involve removing the dipstick side cover and observing the actions of the lift cover lever & how it affects the control valve operation.
Lift arms stuck in up position
Control valve is stuck & can sometimes be released by manually moving the pump control valve lever back & forth. If it's really your lucky day we have on occasion 'unstuck the valve' by picking up & dropping the lift arms repeatedly when the lift control levers are in the down position. Failing this remove the pump, control valve, clean or replace.
Shuddering when lifting implement
The valve chamber valves are not sealing. Either the valves are badly worn, or normally the biggest culprit is dirt stuck in the valve seat preventing proper operation - exess silicone which we see daily - pieces of white backup O rings from careless installation. Only solution is to remove pump & repair. If you need to complete a task carry on as this irritation cannot really cause further damage.
Lift arms drop when tractor engine is stopped
This is not a serious problem & indicates general wear on valve seats, control valve or standpipe O rings.
Lift looses power as work progresses
After a while once work progresses the temparature of the hydraulic oil rises & as is the nature of oil the viscosity drops, IE becomes thinner. If the proformance of the lift weakens this is a symptom of wear. The hydraulics should perform as well at idling speed or at higher rev's.
Hydraulics will not lift
Worst culprit is normally the relief valve which becomes slack (Spring loses tension) due to incorrect operation. If you remove dipstick cover & feel by hand the bypass is obvious. Alternatively cracked ram cylinder, standpipe O rings or lift cover mechanism especially the draught control lever which operates the draught control rod via a small roll pin which sometimes snaps off.