HW100 air leak

[AndyAndy]

Hi everyone, I've had a HW100 for 4 years now & it's developed an air leak.
When I attach the air cylinder, air begins immediately venting from a small hole on the underside of the valve housing at quite a rate. I have changed the 2.57mm x 1.78mm O ring on inlet valve stem but this has had no effect? The cylinder hasn't been removed from the rifle very often & hasn't suffered any damage. Any thoughts on the cause?

KR Andy

[Blackmax]

Valve O rings that form the seal on the brass inlet. You'll need a 10mm and 12mm deep sockets to remove the parts. Get your seal kit from HW Tuning the most reputable company fir the parts.

[Scrinja]

You need a 10mm deep drive socket to remove the main valve assembly
To split it you need a 8mm socket

[hotversion]

Its prob the first tiny o ring you can see when you remove the cylinder.

[krisko]

maybe there is a scratch inside the cylinder side/port. i had similar, had to wrap 600 mesh sandpaper on a drill bit to smooth things out, no more leaks. there is a pneumatic diagram around showing arrows on the arrows it tells you depending on which hole it leaks from, you have to check certain o rings. common sense you have to track the flowpath of the hpa from the cylinder all the way to the leak point.
if it is not an o ring, it is something else.

you dont need full o ring kits, only 2-3 o rings sort most of the leaks in the hw100, all others are humbug even on the woc forum the o ring list is incorrect/dupliates are there and some are missing anyway.

[Scrinja]

There are 10 o rings in a HW100 regulator any one of them failing will give you an air leak Buddy
Repeated below from the WOC is the list of o rings

Here's the full list of factory O-rings and some recommended alternatives All O-rings are NBR 70 unless otherwise stated.


O-ring HW 100, 37.1 x 1.6 Cylinder clamp 2682C
O-ring HW 100, 15.6 x 2.5 Barrel clamp 2682B
O-ring HW 100, 32 x 2.5 (or BS#124) Magazine 2603A*
O-ring HW 100, 13 x 2 Adaptor A 2704
O-ring HW 100, 2.57 x 1.78 Adaptor B 2703B

O-ring HW 100, 3 x 1.5 (PTFE) Valve stem 2655D
O-ring HW 100, 12 x 1.2 Breech block main (12 x 1) recommended 2658
O-ring HW 100, 5.5 x 1 Breech/probe seal .22 2659A*
O-ring HW 100, 4.5 x 1 Breech/probe seal .177 2659A*
O-ring HW 100, 4 x 1.5 Probe buffer 2618A*
O-ring HW 100, 2.57 x 1.78 (PUR70) recommended Main valve inlet 2665D
O-ring HW 100, 7 x 1.5 Main valve outlet 2666
O-ring HW 100, 2 x 2 Main valve internal (2.57 x 1.78) recommended N/A
O-ring HW 100, 7 x 1.5 Regulator piston 2668
O-ring HW 100, 10 x 1.5 Tension adjuster (sometimes omitted) 2672
O-ring HW 100, 8 x 1.5 Barrel 2679

The only one missing is the 14 x 1.5 where the main valve assembly screws up inside the Reg block insert inside 2673 (Later quick fill models)