Silca Pista Rebuild Problem

[bobscott]

I just put a new leather pump washer in my Silca Super Pista floor pump. The down stroke pumps (pushes out air) much better now but on the upstroke I am pulling against a vacuum until the pump washer passes the vent hole near the top of the pump tube. I cleaned up the inner valve in the pump base and it seemed fine/ didn't need cleaning; my understanding is that is should not be involved in this problem as it functions prevents backflow into the pump tube and allows a pressure reading.
Does the washer just need some break-in such that I do not get such a good
seal on the upstroke or is there some other problem involved here?
Thanks

[Too Tall]

Did you give the leather a good coat of white grease? Work it with your hands some to soften the leather up and try again.

[Serotta PETE]

I had to grease mine when I rebult it also..... That worked for me!!

[JohnS]

Buy a Joe Blow! :p

[bobscott]

I did an initial Phil Wood oil treatmant followed by a generous rubdown with white lithium grease.
It is usable but I don't remember getting this upstroke resistance when it was new.
Am I correct that the air that fills the pump barrell on the up-stroke comes from leakage around the downward cupped leather washer? Is there another entry way for air that fills the barrell that might be blocked?
Thanks

[Too Tall]

Man don't make me rub the dirt off my silca pump and LOOK!!! I am very sure you are correct...I think the leather is just plain old stiff. You got the washer centered? Spin the handle 180 and try it...did that help? OK really dumb question to follow: you do have the leather cup facing down as in an upside down cup right?

[bobscott]

Not a dumb but a through question...yes the cup is down. Stiff leather might be the answer. The washer is about 8 years old but, believe it or not, it was stored in a small zip-lock in a metal film can. The leather didn't seem dry or brittle at all; after its treatment the flexibility was similar to the old but shorter/worn washer. The washer is centered.
I will ask again as it might be critical here, the pump barrell fills during the upstroke with air that 'sneaks' by the downward facing cup-shaped leather washer? Lack of flex of this washer could prevent this back flow and produce this problem.
Thanks again

[Kevan]

are there different sized leather pump cups for their different pumps. You know where I'm going with this. Just another stupid question.

[bobscott]

I have only seen one washer for sale in catalogs and at their web site (http://www.silcapompe.it).
Possibly I should go to Silca about this. I have contacted them before with good results. They even sent me one of the new more stable triangular bases for my pump GRATIS. Sent them an Enote to see if they were available separately..... got one in a padded bag several weeks later!
Thanks.

[Too Tall]

As far as I can tell yes air "sneaks" by the plunger leather. You made me look!

[bobscott]

Thanks very much for checking.
I sent a note to Silca and will let you know what they say.
In the mean time, I plan to pull that washer and give it another workover. I am thinking Lexol, Phil Wood oil followed by white lithium. I will report on that as well.
In the past, I had heard that one should use castor oil on pump washers as it was inert with tire 'innards'. I had but couldn't find a small bottle I had used for that purpose, not something I use too often.

[bobscott]

Here is a reply from Silca which goes along with your suggestions

"Try to lubricate the leather washer again, or probably the washer is too tough. Try to handle until it becomes softer."

Tried it and I am back in business.

Thanks for the help on this one. Now I've got a nicer working pump, which I better understand and hope to pass on to my daughter in 40 or so years.

[Too Tall]

Workin' the leather. BD missed this thread or he would have had the correct answer ;) Glad you are back in business.