The International Cessna^® 170 Association

Chris Christensen wrote:I also changed out my sump valves once, for a fairly stiff price.

Examined both and found two conditions:
1- Old shriveled up little itty-bitty O-ring that did not seat well.
2- Small / fine particles UNDER the O-ring which kept it from seating.

Now, I was obviously able to find replacement drain valves, but not JUST the O-ring.
My solutions was to research O-rings for the best fuel friendly versions I could come up with.
Bought a bag of 10 or 20 for a couple bucks.
Replaced the O-rings on my two older drains.

Now I do not have to spend money on new drains.
I was having to change them out every month or so for a while
after have installed the modified Long Range Tanks.

Seems that the problem is over with as of late.
YES, we did everything we could think of to clear any debris out of the tanks before re-installing them. They got a good air-hosing, water-hosing, etc., but still kept getting finite little particles under the O-rings for several months.

PS: it is the same O-ring that is used on the gascolator valve, at least is is on mine.