Hydraulics drop prime again and again.



New member
Sep 5, 2015
Decatur Texas
David Brown 1200a
It almost never primes on its own at start up.
It has a large Kohler 550 front loader and easily looses the hydraulics prime.
At first I was priming by loosening the union on the left side near the step to bleed off the air.
A burst of air would blow out in just a few seconds and the hydraulics would sort of work for a while.
Then I found that the 3 position spool valve on the right just under the seat has a 3/8" extra port
in the cover that i don't see on other DB 1200s. I found I could bleed it there with the spool valve
in the center position. I added a high pressure ball valve there and with a transparent hose routed
the output to the hydraulic filler port. Now I can bleed it by opening that valve. What I discovered
was that after bleeding the system there are still a lot of bubbles going through that tube if I leave
the valve open. The center position of the spool valve is for the 3 point hydraulics, rear position is
external and routs the hydraulics to the front loader spool VALVES.

I've looked for leaks in return and found none...Even coated any place that I thought could leak with
spray glue.
Tried the shave cream, grease etc. Even coated the rubber hose and tightened hose clamps.
Only thing is the pump shaft, Can't figure a way to check it. Just spins off anything i put on it.

Can someone tell me what volume/pressure etc a replacement pump should have?
Sry this is so long... If u r still here THANKS....