How long does it take to rebuild an MF35 hydraulic pump?

[cockeyedMFer]

I've got a broken piston in the internal pump. Debating whether to buy a rebuild kit, or a good used pump from a local dealer. Difference is about $70. I'd prefer to do it myself but don't want to have the tractor down too long. Is it a couple hour job once the pump is removed?

[oldnslo]

I've got a broken piston in the internal pump. Debating whether to buy a rebuild kit, or a good used pump from a local dealer. Difference is about $70. I'd prefer to do it myself but don't want to have the tractor down too long. Is it a couple hour job once the pump is removed?

I guess the big question would be, what else is damaged and would the "rebuild kit" include all the parts that could be damaged. Most piston pumps I am familiar with usually have other components damaged when a piston brakes.

Roy

[SDT]

Rebuilding your MF pump is straight forward for one with reasonable mechanical skills.

Myself, I would NEVER take the time to R & R the pump without properly rebuiding it myself. I would NEVER install a "good" used pump.

Do not expect to rebuild your pump in two hours unless you have done it before.

Dean

[shona13]

G,day Mr cockeyed.
The Massey Book time is six hours that is Shop time for a standard transmission tractor i,e the tractor in the workshop lift cover removed, pump stripped and overhauled ,refitted and both internal and external adjustments completed.

There are a few things that can add time to the job ,one is cleaning If you decide to send the tractor to the shop make sure it is spotless clean.

If the tractor is Multipower It will take about 10 to 12 hours to split the tractor to remove the both pumps.

I would heed the advice of SDT and oldnslo Both should be considered and definitly replace EVERYTHING that needs to be replaced.
Happy days .
Hutch.

[cockeyedMFer]

Guess I'll have to bite the bullet and do it properly then...With winter coming on I can lay it up inside and take my time, but still it seems like every time I think about tearing into it, the next day I need the bucket for something.

Oldnslo - the kit most vendors sell has pistons, valve blocks and o-rings. Would like to know what broke the pistons though before overhauling it.

Shona - its a 35 deluxe, so fortunately no multipower!

[oldnslo]

Cockeyed,
I can not look at the parts breakdown on the AGCO sight for reason so I am uncertain as to style of pump on this model. Is it a radial piston or axial piston?

Axial piston: the pistons run parallel to the drive shaft Usually what breaks on these is the slippers. When these break they usually destroy a wear plate on the swash plate and send metal filings into your bearings etc. Causes can be from excess speed, sudden pressure changes, case pressure higher than inlet pressure, preload spring(s) broken or fatigued from old age, heat etc...

Radial piston: I am not as familiar with but would suspect over speed, or over pressure could break them. Depending on what loads them against the cam this could also have broken causing it to knock.

good luck and keep everything very clean during reassembly.

Roy

[cockeyedMFer]

Here's a diagram - I'd call that a radial piston? Its driven by a 2-lobed camshaft that runs in line with the transmission shafts (not picured)

The square piston frames are thin cast iron, and cracked in half.

[SDT]

The MF pump is a scotch yoke pump. Breakage of the piston yokes is usually caused by debris in the oil.

Comprehensive kits include the yokes and brass parts. Inspect the champers for damage and wear. These are not included in the overhaul kits and cannot be inspected until the pump is disassembled. Thoroughly clean the valve chambers of sediment and debris. You will no doubt spend more time cleaning than repairing.

Be CERTAIN to thoroughly clean the sump including the differential sump while the pump and PTO shaft is out.

SDT