Hi,

When replacing the aux tank transfer pump does the main tank have to be drained or can it be full? Thanks.

Scott

I would think that if the main tank was full, it shouldn't be a problem since the line from the pump comes into the tank at the top of the tank.
It the plane was on an uneven surface then it might siphon out the line to the pump.
Have a bucket handy and give it a try!

Hi,

I thought it should be ok but thought I would ask. Right now both aux tanks are empty but both mains are full. My mechanic has all my books, manuals and even parts cd while he is working on a 337 form for me. Weather here right now is not a lot of fun
( -17f ) this morning I have been meaning to replace the pumps ( one pumps way slower than the other one and the other one seems to siphon into the main while parked ) Thought if I was bored I would go swap them out. Luckily I have a heated hanger. Thank you.

Scott

Not unusual to have one pump faster than the other. Many times it turns out to be a partially blocked vent line rather than the pump.

Running some Marvels Mystery Oil through about twice a year helps keep them from getting gummed up. Check the screens too every annual.

Kirk

Thanks. I got one done today. Some gas drained out of the main tank line until I put a 2x4 under the wing and raised it up about 2" then it stopped. I did find some crud in the screens and magnets the first year I got the plane ( looked like they had never been checked or cleaned ) but the last 300 hours everything has stayed clean. I did the one that siphons back into the main today. When I do the real slow one I will check out the vent. I do add some MM Oil to the gas in the aux tanks everytime I fill them up. I add it at half the rate it says on the bottle. Been doing that for a lot of years. Back when it came in the old metal cans it even said for aircraft use on the can but that langauge dissapeared a long time ago. I can't prove that it helps as a top end lube but no one has shown me that it hurts either. Wish I could trade some of you guys some sub zero temps and snow for a little bit of that mud you are complaining about!

No mud in Virginia highs in the teens all week, got 10" of that white PLAGUE Monday that won't leave 6" to 8" still on the ground and a forecast of-1 for tonight Ant supposed to be this cold around here!

Hello All,

Right transfer pump getting reluctant. Hammer helps but have not figured out how to make that work airborne. Any tricks on the replacement? Found the part number ya'all mentioned and printed out the diagrams from the CD (stick). Looks easy on paper but that rarely works out in real life.

Thanks in advance
Tim

Pretty easy if you have small arms and hands as you will be working through the inspection holes in bottom wingskin.
Make sure the pump grounds well to the rear spar attach points and while you are in there clean up the sending unit ground screw.
And of course clean out the vent lines. Break the joint at the tank and mud dauber debris can be loosened with .040 safety wire.

Jeremy,

Thanks for the pointers. Have a good 4th.

Tim