Cheap fix for most Silca or Vintage Pumps
If you are restoring a Silca pump or vintage pump that fails to pump air, in most cases you can repair the pump by replacing the old leather gasket. We show you how this is done to fix pump as well as a quick DYI cleanup of the inside of the cylinder itself.
1. The first step is to remove the cylinder cap either by unscrewing the cap or removing several bolts that hold the cap on. Remove the piston and examine the gasket for wear (irregular edge, fraying, tears, general wear).
2. To order the correct size replacement gasket, measure the cylinder inside diameter, preferable with calipers rather then a straight edge ruler, to obtain an accurate measurement. Order the replacement leather gasket a few millimeters larger (replacement cost is often under $5). How does one insert a larger gasket into a slightly smaller cylinder opening? Leather treatment will allow the needed flexibility as well as seal around the gasket as one uses the pump.
3. Remove the old floor pump gasket which is held on by a hex nut and the associated washers. After removal, clean the end of the piston, washers and hex nut. I use rubbing alcohol on a clean cloth and stay away from degreasers since any unseen residual degreaser will degrade the replacement leather gasket.
4. To condition the gasket, one can use leather boot conditioner such as mink oil, Bicks, Obenauf's Heavy, or other leather conditioner. Vaseline or a light synthetic motor oil will also work. Rub the condition into the gasket until it become soft. Go slowly, working in the conditioner until the gasket can easily be turned it inside out. Takes about 15 - 20 minutes - continually adding more conditions and rubbing firmly.
5. Clean the inside of the cylinder itself with some rubbing alcohol. I use more rubbing alcohol on the end of the sleeve of an old long sleeve shirt and an old coat hanger that has been straightened. I then push end of the sleeve portion into the cylinder with the coat hanger and turn the shirt sleeve as I withdraw the sleeve.
6. Once you leather gasket is flexible, re-attach the gasket, washer and hex nut. Tighten the nut firmly but don't use gorilla force or you'll damage the gasket.
7. Replace the piston with the new treated gasket by carefully working the gasket, at an angle, into the cylinder and the straighten the plunger and lower the piston into the pump as in the video.
In most cases, such floor pump service will restore pump without the need for an expensive repair kit. One should check and recondition the leather gasket as part of you bicycle maintenance. Now you're ready to fill your bike tires and go cycling