MF 135 Hydraulics

[Donando]

Hi
My 135 hydraulics are very slow & now will hardly left slasher of the ground.
I have checked filter and appears damaged, thus not filtering.
I am guessing some muck may have passed through the damaged filter into the pump.
Do I have to split the tractor to remove Pump ??
Any advice welcome

 

[DavidP, South Wales]

Hello,
Before thinking about the pump it would be wise to check the control spring. This is found inside the housing in front of the rocker yolk where the top link attaches. Fully lower your DRAFT lever and check by hand if there is any end float in the linkage. If there is, this may be your trouble. A topper/slasher might not be heavy enough to produce a problem here but it's worth checking.

As an alternative connect a piece of chain from a pin through two of the lugs on the casting to the top link point on your mower. Temporarily replace the top link. Test the operation of the system. If there is no difference you'll have to look further.
If there is............
As long as your tractor is not fitted with an independant PTO you will not need to split the tractor, only remove the hydraulic cover. Don't do it until you have a workshop manual.
DavidP, South Wales

 

[Donando]

David

Thanks for your knowledge & advice,

I have already removed pto lever casing to access filter, has this any bearing on your advice ?

Regards
Don

 

[Donando]

Hello

How can I tell if the PTO is independant ????

 

[bentrims]

(quoted from post at 01:49:39 10/02/13) Hello

How can I tell if the PTO is independant ????

An independent does not need the foot clutch to engage it, it also will not have a ground drive position. Your problem with the lift. Does it rise jerky? Does it settle down with the engine off? Once it reaches full height does it bob up and down? Poor lift and leaking down might possibly be an O ring on the stand pipe. (The two bolt cover at the RF of the lift cover.) Not probable the piston rings on the lift cylinder. A jerky lift is caused by a bad pump. It is a 4 cylinder pump and uses inlet and outlet valves resembling those of an engine. Usually jerky raise is caused by the outlet valves not sealing. Early pumps also did NOT use piston rings, later pumps DID use piston rings. If the pump had piston rings I recommended Permatran oil. If the pump did NOT have piston ring I recommended sticking with the M1103 Mineral oil.

 

[bentrims]

If you have removed the side cover you probably don't have an independent PTO. To remove the pump remove the RH cover and the roller that controls the pump. Remove the top cover, the PTO shaft the, the rear end drive coupling, be sure the PTO is in ground drive, remove the pump locating pins and lift pump from housing.

 

[Donando]

The lift problem is it won't lift more than a couple of inches.
Used to lift higher, but now won't. did not appear jerky.
May have been slow to lift.
You can feel some thing is happening when seated on tractor (weight distribution wise )

 

[bentrims]

Unhook what you have hooked up. Then attempt to raise 3 pt empty. Does it go fully up? Shut tractor off Does the hitch leak down? Next Restart tractor [u:a0de28f3c8]Being Very Carefull[/u:a0de28f3c8] "Ride" the end of the lower link up. You will then feel if it is jerky. If not jerky AND unit leaks down Pull that transfer cap off and check the stand pipe O rings. If not jerky and unit does not leak down You might need to replace the relief valve. Possible the PTO/ Hydraulic pump clutch disc is slipping. To check turn on PTO and watch the end of the PTO shaft while trying to lift the implement. One other thought, does the tractor Have pressure control?? Be sure levers are in the right position.

 

[Donando]

Bentrims

I have unhooked the implement and it appears to go fully up.

Does the hitch leak down... yes but very slowly.

Is it jerky... yes jerky on up, smooth when on down.

What next steps do you suggest ???

Thanks for your help

 

[bentrims]

The pump used is a scotch yoke pump and pumps only when oil is allowed to enter the pump. The pump works like and engine it has pistons and intake and exhaust valves. If one of those pistons or valves leak too much the hitch gets jerky of course only when raising it. When lowering the hitch the control valve just opens and allows the oil out of the cylinder.
Jerky--When the engine is idling or wide open. Usually it is more noticeable at idle and might almost disappear at anything above idle, if things are good.
When you say the hitch leaks down slowly, do you mean it takes it minutes or hours to go completely down? A quick drop could be an o ring on the stand pipe or extremely worn piston rings on the lift cylinder. Both of which would kill any lifting power. Most tractors do not hold the hitch up for long time, like over night.
Otherwise by what you are telling me I would suggest the pump needs repaired. Can't remember what models they started on but on later models the pistons used a ring on them to help seal the piston. Early pump did not use rings. If the bore in the valve blocks are good you can use rings by replacing the pistons. But the valves need replaced and the seats need dressed. An MF dealer should have a tool to dress the seats.
Remove the cover on the RH side of the tractor. (Dipstick is in it.) then you can check the linkage for any issues and control the pump "by hand". The pump is spring loaded to intake. You might also observe for leaks thru the hole while trying to lift a load with the hitch.

 

[Donando]

Yes, jerky when idling, didn't try above idle,

The hitch leaks down slowly, it took 10 - 15 minutes to notice it had moved from a mark i made on the tryes.

I didn't observe over night, but can if this is your suggestion.

 

[bentrims]

If one of the O ring on the stand pipe was leaking it would quickly leak down. Probably in a minute or less. Unfortunately from what you say it appears as the pump needs rebuilt.