hw100 air dump after reseal

[Mvprotus]

Hi everyone,
I am currently working on my first ever pcp, a Weihrauch hw 100 mk2 ( i believe), which I bought it used last year but recently developed a minor leak, so I decided to do a full kit reseal. I found a few crushed orings (2658, 2677). But the main culprit was the one inside the brass regulator. After putting everything back together, it seemed to be airtight at first, but as I was filling the cylinder and reached about ~150 bar, it suddenly dumped all the air through the barrel instantly. Now, when I try to refill, it starts leaking through the barrel already at 50 bar, and I can hear air escaping near the top of the valve housing as well.
I had a bit of a mishap during reassembly where I accidentally dropped the steel ball from the test port into the screw port. (notice all the scratches from trying to get the ball out) Since I couldn't fish it out, I had to push it out from the inside, which meant I had to push down on a white plastic part. I am not entirely sure what that part does, and I am worried I might have damaged it in the process. (But no air seems to get passed though this hole)
I also noticed that my regulator adjustment screw can only be tightened a very small amount compared to the videos I’ve watched online, where they seem to have much more travel. My washer stack is currently set up as (()) (()) (()) (()) - unfortunatly, not sure if this was the previous pattern. Lastly, the valve stem itself looks to be slightly chipped at the end. It was like that when I had it disassembled. Not sure if this could be the reason why it won't hold the pressure now that the system has been disturbed. My guess is still that the regulated screw has something to do with it, but I have no idea what. ANy help would be really appreciated. Thanks!

---

 

[Blackmax]

Firstly, welcome to the forum, you’ll find a wealth of information on here.

Loads of to cover here, first yours is a high power model, or what we’d call FAC over here so you’re regulator setting will be higher and dependant on calibre.

Firstly it sounds like the valve wasn’t seated correctly when you reassembled it and that’s what’s caused the damage to the valve stem, it should still work ok as long as it’s not too bent. It also sounds like you either had dirt or debris around the valve face and seat or you hadn’t screwed the regulator adjustment screw in far enough, which isn’t a surprise as it looks like you’ve got it round the wrong way. On the reg adjuster screw the hex should face out. If you’re struggling to get it to screw in then the threads may be damaged- go careful it’s only aluminium. It sounds like you’ve blown the valve block O ring in the process. The valve block must be tightened gradually with slight torque on each screw alternatively.

Regulator Belleville washer stack configuration wise, yours is correct for UK guns (sub 16 joules), but you have the high power model block, so it depends on your power limit there and what power you want to achieve. The FAC configuration is (((())))(((()))).

The best way to get the regulator ball bearing out if it doesn’t drop out, is unscrew the grubscrew and cover the hole with a bag, attach the cylinder momentarily and it should blow the ball out. If it’s takes a lot of effort it’s likely the threads on the port are damaged. You can clean these up with an M6 tap.

Be careful which videos you watch on YouTube, there are some in there that offer poor advice, some of which could lead to damage to your gun. If you’re going to use YouTube videos I recommend the Sub 12 Airgunners videos, I’m sure they do one on the HW100.

 

[Horneteer]

Sub 12 airgunners do 2 videos, one for the strip and another for the rebuild

 

[valevelo]

I'm not saying this will solve the issue for you, but my HW100 will sometimes develop a slow leak after filling which I believe is valve related.

Simple fix that's worked for me is filling the cylinder off the gun and then attach to the rifle. Best guess is the blast of high pressure seats something properly- it doesn't do it all the time either, maybe once a year

 

[Blackmax]

I'm not saying this will solve the issue for you, but my HW100 will sometimes develop a slow leak after filling which I believe is valve related.

Simple fix that's worked for me is filling the cylinder off the gun and then attach to the rifle. Best guess is the blast of high pressure seats something properly- it doesn't do it all the time either, maybe once a year

It may be debris and a blast of air can move it so the valve seats. It common and occurs when the gun is filled with the fill adapter on a lead, tiny bits of O rung get shaved off and get in the valve.

 

[Mvprotus]

Thanks everyone for your replies and suggestions.
I decided to start over from scratch. I took out all the seals, checked for any damage, and gave everything a proper clean while putting it back together. Someone mentioned that the fast flow exhaust valve looked chipping and could be binding... so I lightly sanded it to smooth it out. I also gave the belleville washer a quick polish and made sure to follow the correct pattern for the FAC version, including double checking that the regulator screw was turned the right way. The gun is 4,5 btw. Just to be clear, this is how I originally bought the gun (used), so I wanted to make sure everything went back together the same way.

After that, I filled the tank to around ~150 bar and screwed the block in - no leaks at all. I left it overnight, and in the morning it was still at 150 bar. So I filled it up to 200 bars, and still no leaks. But right as I sat down at my computer to write my successful job, I suddenly heard a loud noise as the air started dumping again.
I also tried polishing the exhaust valve housing insert and did a quick suction test, which seem to be tight, but Im not sure how well this test counts, but I’m also certain this small valve hausing is the main cause of the leak.

Any last suggestions, or should I just go ahead and replace it?

 

[Mvprotus]

Quick update: I did overtightened the regulator screw a bit, and unfortunately, I don't have a regulator tester on hand.
However after backing it off a little, it seems to be holding air now. I’m going to try pushing it to 200 bar and see how it holds up.. I believe I've read somewhere that too loose/tight could also cause leaks. (But this is more of a dump)