Hello,
The 3 point linkage and front loader on my 1957 4 cylinder diesel Mf 35 have stopped working, all happened out of the blue, just worked one day then not. I changed the oil which was quite milky, front loader went up once then no more. 3 point kind of tries to rise (judders) but has no power. Any pointers as to where to start looking.?

Best regards David.

Hi David,

First question is does the PTO work. If it does not then there is no drive getting through to the hydraulic pump, which would mean either problems in the clutch or rear end drive. If it is trying to lift a little bit then the above is unlikely to be the problem.

The most likely reason for your problem is that the control valve is sticking. If you take off the right hand side cover (where the transmission oil dipstick is) you will see a lever stuck up out of the oil reservoir with
a small roller on it. Try working it backwards and forwards a few times to try and free it. The spring will return it to the correct position after you have done this. Next run the tractor with the side cover still off. Put the position lever to lift and look inside to the oil reservoir. You will be able to see some slight agitation of the oil because of the rotation of the pump shaft drive; if there is any signifficant turbulence or spraying of oil would mean that there is a leaking pipe/burst o’ring etc.

I suspect the most likely cause of your problem is the stuck control valve.

If freeing the control valve releaves the problem for a while, but then it re-occurs, you may have a scratched control valve or corrosion in it. The milky oil (caused by water in the system) is likely to have accelerated the deterioration of the component. This is why the manufacturer recommends changing the oil every 12 months even if the tractor has not done many hours of work. In fact the less regularly the tractor is used, then the greater
the necessity to change the oil every 12 months.

Hope that info helps make your diagnosis. If the control valve needs to be remove, then watch out for our MF35 Hydraulics Repair DVD to be released early in 2008 which will be of help to you.

Steve, VTE.

Finally found time to have a look inside..

PTO does work ok.

Lever with the small roller on it moves back and forth ok and springs back
when released.

No move ment of oil when running, but there is a bow wave when pto is
engaged.

There is a small amount of bubbling / movement when engine
is runnig..

Off to bang head against a wall…

Sorry to take up your time, if there are any other avenues I can try I’d be
over the moon to try them…

Any other suggestions gratefully accepted,

David.

Next question then….

If you can manage to, get the lift arms to the top position
then stop the engine. If the arms go down unusually quickly then the fault
lies in either the control valve or an o’ring on the stand pipe (pipe that
comes up from the pump up to the cap under the seat near your right hand
leg).

It is possible to check the stand pipe o’rings by removing the 2 bolts
holding the cap and lifting the cap and the stand pipe (tube) out. Then you
will be able to look at the seals and assess their condition.

If the arms will hold reasonably well in the up position then it is more
likely to be a problem with the pump (often the pump valves).

So if it is not the o’rings in the stand pipe then you will have to remove
the top cover (under the seat). Check the bolts that hold the lift cylinder
as it is possible that these could be loose. If that is OK then there is
something wrong with the pump/control valve. To remove it you need to drain
the oil, remove the locating dowels which go through the side of the
transmission housing and prevent the pump from rotating on the shaft.
Remove the differential drive shaft coupler followed by the PTO shaft. The
pump will now lift out.

The pump can then be dissmantled, all the components checked and then
repaired if necessary. Be very careful with arrangement of the components
and make sure that everything is kept spotlessly clean.

Dissmantling and rebuilding of the pump is difficult do describe in words.

Good luck and let us know how you get on. We get so many people like
yourself with hydraulic problems, so we’ll have to press on filming the
DVD!!

Steve.

Checked the o rings on the stand pipe today, one was split the other one was
very worn. I replaced both and things are a little better.

Rear arms rise slowly but judder on the way up, they will just about lift
with me standing on them, front loader tries to lift but only gets a little
way up.

I notice there is a grub screw in the stand pipe housing, is this a vent
plug to expell any trapped air…? I have replaced the oil recently are
there any vents that i should attend to..? clutching at straws now….??!

Best regards

David

Hi David,

The grub screw in the stand pipe cap is just there to block the hole which
has been drilled for the manufacture of the cap. It is not a vent and there
are no other vents to attend to. Bleeding or venting is not necessary due
to the design of the lift cylinder (as the rings allow any air to escape).

I’m afraid you’ll have to take the top cover off and strip down the pump. I
think we’ve exhausted all the ‘easy’ options and possibilities.

Steve.