There was an article several years ago in either the Lancair news letter or the LNN that talk about the addition of the bleed circuit. I have never had my hands on one of these older models. The gear can be made to work -sort of- without the bleed circuit (or even with a reversed spool valve), but the high pressure must be set much higher. Working pressure becomes High Side minus Low Side Relief valve setting.
<<BTW, if you have an older model pump, you do NOT have the spool valve as pictured in Gerards post. In my discussions with oildyne, I believe I understand correctly that the early model pump does NOT have the bleed off circuit (like the guts pictured). Therefore, I'm not sure of your specific problem/ solution. I guess what I'm saying is that Oildyne/ Lancair never really explained why the pumps changed. I assume it was for the bleed off circuit. Additionally, I've got one in my hangar that chirps (a friends) and I'm not sure that our spool valve test holds any relevance to his pump. Chris Z? Any thoughts on the early models?
Post repair inputs are perpetually appreciated.
Larry Henney
L360 800 hrs>>