Dan,
Our pumps have a thermal relief valves that unfortunately have a high nominal set-point of 2,500 psi. The cracking pressure is 2,500-3,000 psi. I wouldn't worry too much about 2,000 psi. -not sure I would like to see anything higher.
The fixed thermal relief valves can be made adjustable by adding a jam nut. Cracking pressure will be somewhat linear with revolutions on the assembly from the time the spring seats to when the housing bottoms out. Count the number of revolutions and then back off the housing proportionately and tighten the jam nut. -for example x.x rev - (x.x rev/2,500 psi*1,900 psi).
The leak down will be harder to find. One or two pump cycles after the temperatures have reached equilibrium is to be expected. After that, you have a leak.
A blown seal will cause the pump to run almost continuously. It only takes a scratch in a cylinder wall to get the leak rate you describe.
Chris Zavatson
N91CZ
360std
From: Dan Ballin <dballin@gmail.com>
To: lml@lancaironline.net
Sent: Sunday, June 9, 2013 2:34 PM
Subject: [LML] Hydraulic Issue
For all those pump experts out there:
I flew my Legacy down to
Monterey few days ago (Thanks to Ralph Love for being such a gracious host). I noticed that my up pressure got to 2000psi, I assume due to heat, it was warm. I cracked the dump valve and it was back to the usual 1500. No issues on the low side when the gear was down - usual 600psi or so. Today flying back to Bend, took
off out of
Gnoss field about 105 on the ground. In cruise at about 14,500, I noticed the up pressure was about 1200 and would slowly drift down to 900 at which point the pump would come on for less than a sec. Seemed like it cycled like this about 4 or 5 times in the 2 hr flight.
So I assume I have an internal pump or dump valve leak and I haven't tried to investigate, but wonder what people
thought. Note that I, unlike a number of you, haven't had this issue before. Could the pressure spike have done something? blown a seal?? How would you go about sorting it all out.
Thanks
Dan
Ballin N386DB LEG2