lml@lancaironline.net Mailing List Archive

Christian,

Operationally I have only ever changed poppets if they were proven to leak. That has happened only once on one pump back in '99. Poppet leaks are extremely rare compared with cylinder leaks. If it isn't leaking, I would leave it alone. To check the poppet sealing you need a few feet of hose (to give the system a bit of compliance) connecting both pump output ports together. You'll also want a pressure gauge in the line to see the time history of any pressure changes.

As far as O-rings are concerned, changing the O-rings on the spool is the most beneficial as it is a dynamic seal. If degraded enough, it could eventually affect pump operation. As a data point, I tested the friction of an 'incorrect i.e. wrong duronmeter' O-ring on a spool that had been in service for 11 years. It was still good - 13 g's to move it.

The poppet valve body and hex plug O-rings are static and see a lot of compression at installation. I rarely change these. If you do, be very carefull in the removal process not to damage the sealing surfaces. Do not use metal tools to pry the O-rings out. They are hard to remove as they are very stiff and sit in a tight fitting groove.

These pumps are immensely robust and rarely require attention

It is interesting how Oildyne/Parker sells these pumps to Lancair for use in aircraft, while a local distributor will not sell you a part for that very same pump. The last time I ordered parts from a distributor, the end use never came up.

Chris Zavatson

N91CZ

360std

www.N91CZ.net

From: Christian Meier <lancair@meier.cc>
To: lml@lancaironline.net
Sent: Sunday, February 12, 2012 8:33 AM
Subject: [LML] Re: hydraulic pump servicing

Chris,

I tried to get a poppet valve from Oildyne in Austria. They told me that they wont sell it because it is an Aircraft part. It will be sold only in a special "priced" kit :-((

As my pump is from 97 I will soon change the O rings. Should I change every single O ring, or just the one on the spool. Does the poppet need to be changed?

My pump works well. There is only a small internal leak on the low pressure side.

I have the asymmetric spool and no springs installed. I upgraded to the -32 pump-gear.

Christian

www.lancair.at

Am 12.02.2012 upm 02:50 schrieb Chris Zavatson:

Jack,

Ouch! That hurts to hear about the rebuild kits getting so expensive. The good news: The only critical part in the kit is the poppet valve, so you only need a kit if the poppet valve is leaking.

The O-ring designations I provided are the industry designation:

013N90

014N90

908

These are for the hex plugs, poppet valve bodies, and spool.

Chris Zavatson

N91CZ

360std

www.N91CZ.net
From: "marv@lancair.net" <marv@lancair.net>
To: lml@yahoo.com
Sent: Friday, February 10, 2012 7:26 AM
Subject: [LML] Re: hydraulic pump servicing
Posted for JON ADDISON <jraddison@msn.com>:

Chris
The Parker pump kit (634412) went from $60 to now $123.  In a direct email to
me you indicated the o-rings of interest are 013N90, 014N90 and 908 durometer
90 (from McMaster) Thought I'd try and share that info with the rest.
It appears a blackish seepage is emanating from the top of the pump itself
and running down the side of the pump into the reservoir. I haven't
investigated it yet by taking it off the adapter.
Also, been looking at gages.  So far 1 1/4 inch is the smallest and
electric/sensor driven.  Hydraulic driven directly at that size only goes to
2000psi and only good for 115% over pressure.   It appears to me that with
over temps driving, we would best have at least 3000psi capability.   What
have others found??   Also, if hydraulic-direct gage is used with a 3 foot
line will the air purge itself out since there is no return line??
Jack Addison360JS
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