Larry Jaques wrote:

On Fri, 03 Sep 2010 17:15:22 -0500, "Pete C."
wrote:

I stuck to hydraulic pump back on the tractor today to see what the
symptoms are. There appears to be some fluid flow, and the lift will
track the position control lever very slowly as long as there isn't any
weight on them. If I stand on the lift arms they go back down, even with
the position control up. It would appear that the lift piston probably
needs new seals.

Springs die and leave spools in the wrong position, too. Rebuilding
the control will solve it.

Suspect not, since the position control does work, which means that
spool is working properly. The movement is just very slow and the lift
has no strength.

Relief valve stuck open perhaps so it can't develop pressure, perhaps
the pump having suction side problems, and likely still bad seals on the
piston.


I pulled the pump back off and opened it up and it looks ok. The pistons
don't seem to have any notable scoring, the valve balls look good and
the valve seats look ok as well.

You didn't mention springs. They can be crucial to proper workings.

They seemed good as well, both the valve ball springs and the piston
return springs. Swash plate doing it's thing smoothly as well.


I pulled the line set off so I can clean them out, and I guess I'll be
pulling the lift cover so I can tear into that and also clean out the
hydraulic sump fully. I did drain the fluid after the test and it didn't
look bad, probably fairly recent. It will be replaced with UTF once I do
seals on the piston and anything else I find wrong.

Also, I can't seem to budge the test plug, which is going to make it
rather difficult to install a pressure gauge to see what pressure I'm
getting.

Thoughts?

Quick, hot touch of an o/a torch flame on the housing next to the plug
usually works. Got hex socket or square end plug? The right tool and
a direct line to get at the plug always help.

I'm going to track down an Allen drive socket and perhaps use it on my
impact wrench to help break the plug free without lifting the tractor
off the jack stands. Also have O/A torch if needed.


Sometimes it's quicker to make (or have your hyd line builder (NAPA?)
make) up a quick inline test hose. Most of my work has been on
automotive power steering and brakes, but I've watched a whole lot of
equipment being repaired. (Me strong like ox, smart like trak-tor)

It's a hardline set with O-Ring bolted flanges, not so easy to do an
inline,


--
Happiness comes of the capacity to feel deeply, to enjoy
simply, to think freely, to risk life, to be needed.
-- Storm Jameson