Checking for a Leak - HW100 Block or Air Cylinder?

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Is it the gun or the air cylinder that is leaking?  The easiest way to check is to remove the Weihrauch air cylinder from the gun by unscrewing it from the block.  You do not need to empty the air cylinder of air.  You will hear a hiss as it is unscrewed, this will stop after a few seconds.    

Once you have removed the air cylinder from the gun, remove the dust plug from the fill port & whilst the air cylinder has some air in it (it doesn't need to be full), pop a balloon over each end of the cylinder - making sure that you cover the seam where the end caps are screwed onto the steel tube (as pictured).

If one of the balloons inflates (as pictured), this indicates that there is a leak on the air cylinder - and now you know which end the leak is at.  CLICK HERE for a guide on removing the end caps from your air cylinder for servicing.

  If neither balloon inflates, then the leak is most likely to be on the gun itself....

Remove the balloons from the air cylinder and screw it back into the gun.  Remove the stock from the gun (it's just 2 bolts underneath the stock) and using either leak detector fluid or some water and washing up liquid on your finger wiped across the 3 holes on the bottom of the block, try and determine which hole the air is leaking from - you will see small bubbles.  Depending where the leak is coming from will determine which seal will most likely need replacing. 

Full Seal Kits can be found HERE.  Individual seals can be found HERE.

If air is leaking down the barrel,  this usually happens once you have had the regulator block apart and the exhaust valve has been moved from it's original seat.  Over time, the plastic of the exhaust valve moulds itself into a position in the exhaust valve housing & once it is removed, it usually doesn't go back into exactly the same place. It also doesn't help that the housing insert is secured into place by 2 screws on a diaganol to each other - over time, they pull the circle into a very slight oval shape, which allows air to get past the valve  -  you will need to polish the exhaust valve insert "dish" & re-seat the valve...  

CLICK HERE to view the video to show you how to polish the exhaust valve seat.

In extreme cases, or if you cannot polish the valve seat yourself, you may need to replace the exhaust valve housing insert (approx £29).