I just cross posted this with the Mechanics Forum since this is a new model. But since this such a "Hands-On" group I thought I'd see if anyone else has had this problem and discovered a remedy... apart from just returning it to a bike shop. I'll let everyone know if any of the pro mechanics offer any useful info.

I've owned various HP and HPX pumps for more than 20 years and never experienced this before.

I have a new HPX (ASV) pump which has only been used on a couple of occasions. It has never been dropped or misused and still appears to be in virtually new condition. BUT... today, just when I needed it (of course) the pump failed to inflate a punctured tube.

After returning home I discovered the problem is that air is now also exiting the pump head from the thumb-lock side of the pump head, rather than exclusively pumping into a tube valve.

No parts are missing and this model accepts both Schrader and Presta valves without switching or flipping the valve washer, so nothing internal was ever messed with since purchase. I have an identical pump in a different length and it still works fine after a lot of use.

Is there any sort of consumer repair I can make to what I assume is a blown internal seal somewhere in the pump head? I don't even know if such parts are even accessible, but I would think the thumb lock retaining pin (spindle) could be punched out to remove the thumb lock lever. Unfortunately, only the most basic and obvious replacement parts for this pump are shown or listed on the Zefal website.

Appreciate any advice. ~ Thanks!

Here are a couple photos showing this latest "ergonomic" model which features their traditional alloy construction, and now with soft rubber grips on the handles and a slightly angled pump head:

it sounds funny that you do not need to change anything since the diameter of the valves is so different. if it worked a few times then started doing this I would go back to your shop, (I hope it isn't far, but atleast it will be a beautiful ride) and seek there advice/assistance. with the older style HPX I have seen where the collar that holds everything together vibrater loose and even fall off.

I haven't seen one of these "new" Zefals before, and tho the little diagram shows both P and S valves "go here" I'm sure there must be some adjustment to accommodate the 2 different diameters involved. So I'll guess you have to tighten the cap when you fit this to a P valve to compress the washer more and get the all-important seal around the P shaft.

Well, I THOUGHT I had discovered the problem...

The new pump heads have a different construction than earlier models. Rather than a plastic sleeve they now feature a barrel or "piston" made of rigid plastic. When this more solid part is pushed by the locking lever it indeed compresses the valve stem washer with greater force than earlier pumps - pressure sufficient to grip either Schrader or Presta valves. Like the piston of a car engine, that plastic barrel in the pump head has a seal. In this case it is a rubber o-ring placed on the end near the lock lever. I had assumed there was a problem with the o-ring. Alas, this was not the case.

After immersing the end of the pump in a bowl of water, it immediately became obvious that there is air leaking... but, it is coming from a seal between the pump head and the shaft. This seal is definitely NOT something which I could easily access or repair. The shaft is not threaded into the pump head, so any seal or gasket (which is concealed by the outer grip) must have been simply pressure fitted during manufacture. So, no easy fix. Looking down into the shaft, it appears to be the same as the construction of earlier HPX pumps... again, not a clue whether those could be repaired either.

Well, at least I did learn some interesting facts about the new pumps during my futile quest for a solution.

Unlike earlier models which offered a loose fitting lever axle (I assume for easier removal of the lever, and then to access the inner parts), this lever pin is not made to be easily slipped out of position. Because there is really no reason to ever remove and reverse the valve stem washer, there is really no reason to disassemble the pump head. However,... the entire mechanism still can be removed with little difficulty.

Because these pumps are so distinctly different from earlier models, I thought everyone would like to see a closer look at the "guts" of these pump heads.

Thanks for the look at the internals. I was not aware that Zephal was making a new pump. With these problems, it makes me value my alloy/steel made hp's and hpx's even more. I can rip them apart easily and have replacement parts available if need be. Metal outlasts and outperforms plastic every time.

thanks for the clear pictures and details: you've convinced me NOT to buy one

I lost an HP-X years ago. A friend borrowed it and proceeded to air up his tires. He pumped furiously hard (i guess he was trying to impress us or something). He jerked the head around as he pumped, exerting significant force on the head and valve body. The pump was fatally damaged - the beer-can thick aluminum body was ripped at the rivets/swage (or whatever) where the head was attached. This sounds like the same thing. I have another & it's been fine but I am very careful.