Air leaking in SKS Rennkompressor pump

[Rob Lindauer]

My recently-purchased pump seems to leak air when I'm at about 2 bar / 30 lb

When I start to inflate a tire, the first couple strokes (up to about
30#b) work normally.

For the next several strokes (around 30#), it seems that air is leaking
past the plunger (don't know the correct terminology for the barrel
washer or whatever that actually compresses the air). I can hear a lot
of hissing air, and the strokes seem pretty ineffective, not much
movement in the pressure gauge.

Once I get a bit above 30# (up to 100#, which is as high as I go on my
bike), the pump seems to work normally - no more leaking air.

I presume this is not normal behavior. Can you guide in what corrective
steps to take? Replace the barrel washer (eyeballing mine, I don't see
defects, but I don't know I'd recognize one anyway)? Lubricate the
barrel (and what's the recommended lubricant)? Something else?

Thanks in advance for any guidance.

[thirty-six]

Post by Rob Lindauer
My recently-purchased pump seems to leak air when I'm at about 2 bar / 30 lb
When I start to inflate a tire, the first couple strokes (up to about
30#b) work normally.
For the next several strokes (around 30#), it seems that air is leaking
past the plunger (don't know the correct terminology for the barrel
washer or whatever that actually compresses the air).  I can hear a lot
of hissing air, and the strokes seem pretty ineffective, not much
movement in the pressure gauge.
Once I get a bit above 30# (up to 100#, which is as high as I go on my
bike), the pump seems to work normally - no more leaking air.
I presume this is not normal behavior.  Can you guide in what corrective
steps to take?  Replace the barrel washer (eyeballing mine, I don't see
defects, but I don't know I'd recognize one anyway)?  Lubricate the
barrel (and what's the recommended lubricant)?  Something else?

Clean and lubricate the barrel with silicone lubricant.