point92mach

Ok, we are on our next mission, fixing the port k-plane trim pump.

The problem was that the plane would extend, but would not retract.

Only cracking the extend hydraulic line to relieve the existing pressure would allow the trim tab to retract, and even then it was super slow.

After disassembling the reservoir, I noticed that there were three pressure relief valves, and one (the retract pressure relief valve) had no jam nut on it....it was completely backed off.

I believe the extend pressure was way too high, because the motor would stop once the trim tab was fully extended.

I also believe that the hold pressure was set way too high as well.

So.... I have a new jam nut for the retract pressure relief valve, and it is time to reassemble.

What pressures should these three valves be set to? What is a good way to rig up a test gauge to the outputs, or is that even necessary?

Thanks!

Greg

point92mach

Well, in the absence of any other information, I got the pump working by swag'ing the relief valve settings.

I simply adjusted the valves so that the motor growled good and low with the outlet blocked off.

This method seems to work good on the drive trim pumps, too, because I was unable to trim the drives up when under power. After adjusting the relief valves in the pumps the drives seem much more responsive.

Greg

Wally

check this out: http://www.boatfix.com/merc/Servmanl/6/6A5R3.PDF

This should help ya

point92mach

Wally,

That was MOST helpful, thank you for taking the time to help me out.



Greg

Wally

no problem...glad i ran across your post to help ya