more hydraulic problems

super6 · Post by **super6** » Wed Aug 12, 2009 4:26 pm

after cleaning and putting new seals on my diesel major i found it would not lift a huge weight and would make a tick sound at end of lift.
i then removed unload valve and rechecked, it was a little sticky so i cleaned and resealed again, ( it currently has 2 thin shims on).
i used tractor again today to lift drawbar on a 12' ifor williams flatbed trailer( not heavy just jockey wheel did not have enough travel) and hydraulics just lifted it of ground 2" and then ticked, i can get a little more lift be repeatedly lifting arms but not much.
where do i check next cheers Brett

henk · Post by **henk** » Wed Aug 12, 2009 6:22 pm

Super6,

The tick must be the valve that opens when pressure comes to high. Seems to me there some leak in the system. Problem ofcourse is were. Maybe you can remove one of the shim rings and try again.

super6 · Post by **super6** » Wed Aug 12, 2009 6:31 pm

would it be better to remove a shim or add one.

Emiel · Post by **Emiel** » Wed Aug 12, 2009 7:36 pm

Hi,

Without having heard the "tick" it is difficult to say what it is off course.

When the tick really is an valve which opens, then it might be the maximum pressure release valve. Adding or removing shims without knowing what the opening pressure is at the moment is not a good idea. This can easily get dangerous.

Better is to fit a test gauge to the pressure tapping on the left hand side and check what the opening pressure is. Pressure and procedure has been described by Brian on the board some time ago.

Other questions:
-what seals have you replaced?
- what type of oil is filled into the rear axle housing?
-might there be sludge/debris in the pump intake filter, thus making the pump starve for oil?

Best regards

Emiel

super6 · Post by **super6** » Wed Aug 12, 2009 7:40 pm

i have changed all o rings in the valve chest and piston seal.
new oil in rear end and i have cleaned out guaze at bottom.
Are there any other valves to remove other than the ones under the two plates under the seat?

Post by **Brian** » Thu Aug 13, 2009 7:53 am

The "tick" is the unload valve blowing off. This is normal and no problem.

You do not have a problem.

There are not enough shims in the valve but you need to fit them using a pressure gauge.

Grani · Post by **Grani** » Thu Aug 13, 2009 8:09 am

The old pressure valve makes the tick and then it drops the pressure. If you change it to a new model valve it holds the release pressure at the maximum without the tick and the pressure drop. The old valve has 1cm long cap and the new has 3cm. The max pressure is still the same. Use a pressure gauge when changing the valve to prevent pump damage.

Post by **Brian** » Thu Aug 13, 2009 8:21 am

Be VERY careful.

Not all valves are interchangeable. The latest valve will not fit in some earlier units and the complete valve chest has to be changed.

Some earlier units parts are not all interchangeable with the later ones. according to the service book.

super6 · Post by **super6** » Thu Aug 13, 2009 5:48 pm

can i check pressure at tipping trailer socket, and if so what pressures am i looking for, lowest to highest safe range.
thanks brett

Post by **Brian** » Thu Aug 13, 2009 6:00 pm

Yes, that is where to test it. 2000 to 2200 PSI when hot at around 1400 rpm.