hydralic pump question

02-13-2011, 06:04 AM

mike reibling | hydralic pump question

Yesterday I went out for the first flight since Nov 7th. Wow it does not take long to get rusty. It was a nice day about 32 degrees and a friend of mine that came along is going to post some video taken on utube.

About a month ago when I was at the hanger I turned on the master switch for the first time in 2 months and the hydralic pump must of ran for 30 seconds before it pressured up. Yesterday it did the same thing. After it pressured up once it seemed to work normal. The reservoir was and still is full. This seems like something not right. Does anybody have any ideas?

02-13-2011, 09:44 PM

keithw | Mikes Hyd. Pump.

Hi. Mike. It seems to me that your pump is acting alot like mine did. I ended up adding Gransville Hyd additive (Aircraft Spruce) I think I miss spelled Gransville but you can fig it out . I think the oil drains out of the pump portion and takes awhile toget its prime. The additive not only heps at the pump but helps the whole system, leaks etc. Also I use it in repacking my oleo's. Good luck and great to hear from you. Looking forward to the (Air Venture Race again this year. Keith Walljasper N80CC

02-15-2011, 12:48 AM

mike reibling | Thanks Keith

Good to here from you as well.

I purchased some of that at Oshkosk after the race last summer for my oleo's.

Did it correct the problem completely in your pump?


02-15-2011, 08:24 AM


Hi Mike & Keith,

Good to hear you are flying in the winter time.

I also added Grandville to the oleos and the leaks stopped for a while. When the leaks returned I purchased 2 new oleos and have not had any problems to date.

The cycling of the pump is another issue. Any, and I mean any air in the lines or leaks will cause the pump to cycle. My accumulator diaphragm sprung a leak last year so I had to replace it. The one I found is the same one that Mike Bowes suggested years ago. It is a little bigger and takes about 30 seconds to pressurize the system. I found a place in Texas that I believe has a direct replacement for the little hand grenade type you all use now.

When sitting air will enter the system. Over time the 30 seconds should get shorter.

Good Luck and Happy Flying