Massey Ferguson MF135 1965 model - hydraulics problem

[DougMF135]

Hi there, Anyone up for a mechanical engineering detective story based on my 1965 MF135's hydraulic system.
Serial number of my tractor is 118536.
Symptoms:
Many operating hours, and about 10 years, ago the multipower engine braking in "hi" failed for reverse only.
Very recently the multipower no longer selects "hi" at all. The knob and linkage moves, but nothing happens.
At the same time the 3 point linkage no longer lifts, but in a very strange failure mode. At absolute dead idle, the 3PL will lift, including a reasonably heavy slasher. But at anything much higher than idle, including all the way up to full revs, nothing moves. This really surprises me as I would have expected it to be the other way around if there was wear and leakby somewhere. Once the 3PL is raised, very slowly, and then the engine shut down, the 3PL still takes ages to slowly drift back down. No change to how it's been for years - perhaps takes 20-30 minutes to go from fully up to down.
I have checked the oil level with the dipstick on the response speed quadrant. Seems ok.

So the detective story begins - please help me write it by challenging my assumptions and adding anything from your knowledge.
Because the 3PL takes ages to drift back down, I'm assuming that the actual lift cylinder and control valves for it are OK.
Does the "operate slowly at low speed, but not at high help anyone???

What do you think please?
DougMF135

 

[KevinKing]

This should be the system you have. I would start with the relief valve.

 

[DougMF135]

Thanks KevinKing,
I haven't committed to disassembly yet. Any tips for checking the operation before stripping it down? I am going to try and find a pressure gauge, to see what is happening in the main oil gallery.
Doug

 

[DLTTrekkers]

I will start by cleaning the hydraulic filter and replacing the oil .

 

[DLTTrekkers]

I will start by cleaning the hydraulic filter and replacing the oil . First check if you can remove the filter from the bottom ? That will make it very easy

 

[KevinKing]

You can always start with the filter and fluid first. That will rule it out.

 

[shona13]

G'day Doug MF135.
The first problem is the hydraulic filter is blocked to remove it there are two types of pump fitted to the 135 the first pump is a mark two pump,this can be identified by looking at the lift control quadrant ,the two semi circular plates that the levers follow, where the plates are attached to the lift cover there are two Spacers,round tubes that are fitted between the plates to hold them apart, if they are indeed round this is a mark two pump ,if they are Hexagonal the tractor is fitted with the later Mark Three pump.
To access the earlier mark two pump filter first drain all the oil ,approx six gallons ,two drain plugs one roughly below the clutch pedal and the other further back about where your left heel would sit when on the tractor,remove both plugs and let drain completely then remove the sideplate ,six bolts left hand side the one with the pto lever,remove it and look inside and slightly towards the front and you will see a piece of twisted lockwire ,cut the wire with side cutters and screw the filter cap and filter of, try to keep everything together as there will be a lot of undesireable crap inside the bottom bowl of the filter, the filter is either brass or stainless steel gauze and can be washed out in petrol provided the mesh has no tears or cuts in it sometimes when the filter gets old the rubber Flanges moulded onto each end of the filter become brittle and fall apart ,best to replace if this is the case, all good get a new piece of soft tie wire and thread it through the top of the filter where the old lock wire came from ,twist the lock wire a few times and leave the ends, refit the filter ,dont forget the large O ring on the bottom, when tight ,by hand is good thread the end of the lockwire through the hole where the old wire was located, replace the cover with a new gasket making sure you engage the pto pin on the cover with the grove on the pto gear if you mark the pto cover before you take it of it will be easier to do this part .

If you have a Mark three pump the filter is accessed from the bottom of the transmission about below where your left heel would be when sitting on the tractor ,a triangular shaped plate with three bolts 1/2 " a/f. Ring spanner/socket,drain the oil remove the plate look inside and you will see a small safety clip remove the clip and remove the nut,spring,washer and filter assembly noting how it all came apart again clean or replace the filter assemble ,don't forget the large O ring,refit the filter access plate use a new gasket and refill with oil,note when filling with oil you will notice that the gearbox is filling up but the oil level on the ddipstick still shows low, it is best to pour say half of the oil in and wait five minutes to allow the oil to reach the rear transmission and pump area there are only two small holes to allow the oil to flow through and it takes some time to reach the rear, slowly top the oil level up to the full mark.

If the hydraulics are going down slowly the only thing that wil stop them is the Response lever ,right hand side next to the transmissoin dipstick ,it travels from slow to fast ,it's purpose is to control the rate of drop that is if you set the lever on slow it will allow the linkage to SLOWLY drop thats all it does, Intended to be used when you have an implement on the linkage especially a heavy one like a brushcutter where you want it to lower slowly and safely it restricts the flow of oil from the control valve to sump BUT and it is possible that the response lever has been adjusted wrong at some time and what it does if you like, it goes to far into slow and actually stops the linkage from lowering at all,if this is the case and it bothers you i can take you through the resetting procedure but if you are aware of this being able to happen do not go to far towards Slow then that will be ok .
Regards.
Hutch.

 

[DougMF135]

Thanks Shona13, KevinKing, DLTTrekkers,
OK, I've had the PTO cover plate off now, and found the main filter, cleaned it out - was absolutely full of gunk - and the 3PL hydraulics are working fine again. But still no multipower. I've subsequently been told that the multipower has an internal filter too. But where? I've seen another thread where there is a photo showing it just forward of the main filter on a 1968 135, but on my 135 there is nothing in that space. Any ideas before I take the cover plates off both sides please?

 

[shona13]

Thanks Shona13, KevinKing, DLTTrekkers,
OK, I've had the PTO cover plate off now, and found the main filter, cleaned it out - was absolutely full of gunk - and the 3PL hydraulics are working fine again. But still no multipower. I've subsequently been told that the multipower has an internal filter too. But where? I've seen another thread where there is a photo showing it just forward of the main filter on a 1968 135, but on my 135 there is nothing in that space. Any ideas before I take the cover plates off both sides please?

View attachment 499518

Remove the right hand side plate ,the one with the transmisson dipstick and you will see the multipower filter it is kind of rectangular in shape,to get to it the lift cover will have to be removed but before you do that check that the multipower lever is working properly ,move the lever up and down and look where the lever/rod goes into the transmission housing(underneath the battery) make sure the rod moves when you operate the lever you should feel a definite "Click" if not the lever could be out of adjustment , let me know what you find.
Happy days.
Hutch.