My Silca Super Pista pump won't break the presta valve seal to allow pumped air into the tube. It sounds like it's bleeding off from the pump itself. I greased the seal and still no go. Any ideas ?

Thanks in advance

I've always slightly tapped the presta valve BEFORE putting the pump head onto it. This has allowed air in with every pump I've own when it seemed no air was going in. A slight tap of the valve doesn't let that much air out but seems to free up the valve and the existing air pressure for air entry.

Silca pumps have a ball-type "check valve" in the base that only allows the air to flow one way. If the valve sticks open, the pump won't develop pressure. Remove the brass hex-head plug under the presure gauge and clean out the valve.

It was the check valve ! Thank you very much. Say what you want but this internet thing is the best.

Some Silca pumps can stop working because the rubber seal on the end of the rod (think a small plunger) can dry out and shrink/shrivel if the pump was taken apart for some reason. Then no amount of grease can make it "grow" back to the correct proportion to fill the metal barrel and be able to pump. This happened to my nice Silca pump a few years back, and I've been using a cheap Nashbar model since then.
My question: does anyone know whether you can buy these sorts of parts (the rubber "plunger" head) from Silca?

The plunger in my Silca track pump is made of leather..... but you should be able to order replacement parts from any bike shop, or here:

https://www.loosescrews.com/index.cgi...id=14318526799

Try Yellow Jersey in Madison Wisconsin, they have a lot of silca pumps.

Right on, Svr and San Rensho - thanks for the recommendations. I may order some pieces from loose screws. No idea that the plunger piece was leather until I looked at it carefully after taking the pump apart. It'll be good to use it again and keep the cheap Nashbar pump on schraeder setting to use with my commuting bike.

Edit: the leather plunger piece has re-expanded from sitting inside the greasy pump barrel for a couple of years when the pump has been in my attic. So I don't need to replace it.

With any Presta tube I've always twisted them open a full turn, depressed the stem with my finger to break the seal, jammed the Silca head on the stem and pumped away.

If you hear air rushing out of the Silca Head, it might need to be screwed down a little tighter ... that expands the rubber washer for a better fit.

If you hear air rushing out of the base of the pump, the hose and seal might need to be tightened a little.

If you hear air escaping towards the top of the pump, the leather washer is drying out. Just a little dab of oil on the leather works for me.

Other than that, the check valve in the base might be sticky. Usually it only gets that way if you overdose the leather washer with oil and the sludge accumulates around the needle valve ... easy to dissasemble and clean in any event.

I've got the leak in my Silca floor pump isolated. (It's the Super Pista, the old version with wooden handle but only one footrest - the updated model has two places for you to step on the base and hold the pump down with both feet.) It's not a problem until 80 PSI or so, but a little air leaks at the fitting between the bottom of the long tube and the brass piece to which the pressure-gauge and tube connect. I've tightened the base (which holds this joint together as much as possible, having put a bit of bearing-grease around the joint first. It's possible that there's not supposed to be any grease there to help the seal (i.e., the design is that the brass would deform under hard tightening pressure, and thus seal the connection), so I'm going to take it apart again and try cleaning the grease off. Any thoughts in the meantime?

Okay, update on my situation: the leak indeed does occur at the fitting between the bottom of the main tube, and the brass reservoir piece to which the hose and pressure-gauge are attached. That connection is metal-on-metal, and it seems as if there should be some rubber piece that seats between them. Loose screws and other places don't have a replacement part there; anyone know where I could get one (or if there is indeed supposed to be a rubber seal there)?

The check-valve itself is fine. It's clean inside (I took it apart just to see the setup), and there certainly isn't any air flowing backwards.

Clean the grease out and put in a few turns of teflon thread tape. I use this on all my air compressor fittings to make them nice and snug.

Hey, it turned out that I could just buy a tiny rubber gasket at a local hardware store for 30 cents. That's what's supposed to go in between the two metal faces, stops any leakage. I have a whole pump again.

Also, if the air is leaking out between the valve stem and the pump gasket, try tightening the nut around the gasket to shrink the opening where the valve fits. Observe the nut to make sure it isn' already fully seated and can't be tighted any more. If so, it's time for a new gasket.