On Fri, 13 Jun 2014 00:45:51 -0400, John
wrote:

Larry Jaques wrote:
On Thu, 12 Jun 2014 08:42:50 -0700, wrote:

I have a mid 70s Case CK780 backhoe. The thing had seen lots of abuse
before I bought it and I have used it pretty hard since. The power of
the hydraulics has gotten weaker over the years. I used to be able to
kill the engine by trying to push or pull too hard. Now this doesn't
happen. So I'm thinking that the pump has a lot of wear. Over 30 years
ago I used to repair gear pumps in a lumbermill I worked in by
grinding the end plates of the pumps to remove scoring. But I don't
know how much more pressure the pumps put out after this repair, it
was just what I was told to do and I did it a lot. Considering the age
of the tractor I'm wondering if I might just be better off buying a
new pump and also if there is somwhere else I should look for the
lowered power of the hydraulics. The power loss has been gradual over
the years so I'm thinking it's probably the pump.

Don't overlook the pressure regulator, Eric. Maybe try a new spring
there to see if it puts the Oomph! back into it.

--
It is characteristic of all deep human problems that they are
not to be approached without some humor and some bewilderment.
-- Freeman Dyson

The Case uses a two stage pump, one stage for the front bucket and one
for the hoe. An easy way to check the pump is to curl the hoe see
what the engine does. If the rpm holds with little extra stress and the
govenor not cutting in too much you most likely have a bad pump. Do this
on both the how and the front bucket to check each section of the pump.
Also get the hydraulic oil tested and that will tell you if the pump
is worn out. It costa about15 bucks.

John
Thanks for the advice john. The engine behaves as described. I cannot
lug the engine too much by pulling or pushing too hard with the hoe. I
do not think however that the pump has different sections, one for the
hoe and the other for the front bucket. There is only one outlet from
the pump. It goes into the valve for the front bucket and from the
valve oil goes to the hoe.
Eric