Air loss through the barrel when installing M3 powerblock kit

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Enkey

Enkey

Member
Jun 14, 2015
854
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Illes Balears, Spain
Hi
I have installed a powerblock on an M3.The M3 kit is reduced in the number of parts that compose it. I have to mount a new Valvehouse, Impact, Power Plenum part number fx 20671 in which the valve seat is included with a used part which is the valve part number fx 20275. The problem that causes me that combination of used part with new part is a small air leak, my intention is to rectify the valve and seat with the same technique that is used in the valves of the engines but before I would like to know your opinion or your experiences.
Regards
Enkey
 
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Work slow with mild abrasives and low pressure if mating the two surfaces together via lapping. I use toothpaste and work it by hand personally, some use a drill. I also lightly burnish by hand rather than drill as well, its more tedious and time consuming but if the surfaces are machined square enough, you really shouldn't need power tools to mate them together.
 
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Stubbers said:
Work slow with mild abrasives and low pressure if mating the two surfaces together via lapping. I use toothpaste and work it by hand personally, some use a drill. I also lightly burnish by hand rather than drill as well, its more tedious and time consuming but if the surfaces are machined square enough, you really shouldn't need power tools to mate them together.
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Hi Stubbers
I didn't know that toothpaste was a mild abrasive.
Thanks for the information.
 
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Lapping is most definitely a common way to deal with a leaking poppet / valve seat. Mild or aggressive abrasive as needed depending on the severity of the flaw. Color the mating surfaces with a black Sharpie or dye, then spin the surfaces together for a short time, and wipe it clean and view the surfaces with the aid of magnification. The low spot(s) will still have the marker. Continue lapping until all the marking is removed and you have a smooth, continuous ring of contact.
 
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N1neWivesSniper said:
I wonder if you have the old 20275, they increased the size of the poppet to help with these leaks, I bet I could tell if you have a picture.
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Hi
I finally disassembled my M3 and found the mystery of the air leak.

IMG_20230412_105515.jpg
IMG_20230412_074527.jpg
IMG_20230412_164021.jpg
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Do any of you know the difference between these powerblock kits?
Fx 20845 and Fx 20825
Thanks
Regards
 
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N1neWivesSniper said:
The kit looks right, they started putting removable valve seats back into the plenum house and increased the poppet size.. Your kit looks like the updated parts.
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IMG_20230412_203434.jpg

If I buy a powerblock M3 kit and they have modified the valve seat size it should come with the valve corresponding to that modified seat.
These are my thoughts, Now I have two problems
 
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Hi guys

Fx has modified the valve seats on the M3 powerblock to be removable and larger diameter Fx 20671-1 and the valve is also larger diamerter Fx20860.
The valve fx 20860 is not included in the kit for M3, must be purchased separately
If you bought the new powerblock kit for M3 and you have an air leak through the barrel you need to buy the new valve as well.
Regards
Enkey
REMOVABLE VALVEHOUSE M3 FX20671-1
 
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After several attempts fitting my power block kit (20845) in my M3 and dumping almost a full bottle of air I gave up. I just didn’t understand. I followed the video instructions of both Matthias of ‘Airbuks’ and Ernest Rowe of ‘FX masterclass’. Neither even mentioned the Valve seat.
Then I started to search the net and ended up here.

I purchased the kit trough Huma Air here in the Netherlands. In the box was a pack list. On it number 20860, the valve seat and accompanying o-ring 19720. Only these 2 items were not in the box.

I didn’t think anything of it because the valve seat was on the valve rod and they also make you re-use the o-ring underneath the manometer. (I think FX is too cheap. Why don’t they just supply all o-rings needed I wonder, but that’s another matter)

But after finding this post I started to measure and discovered the valve seat is too small for the new valvehouse. I think it’s ludicrous that you have to find out yourselves and even more insane that they might make you purchase that part separately while it’s on the pack list of parts that make the upgrade kit.

Did you end up buying the new valve seat?
I now have to wait and see what Huma air says. I’ll have to wait for them to answer my mail request. There’s no phonenumber on their website.

The only way I can shoot for now is by fitting the old block and valvehouse.

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For the people interested in solving the problem I have with the Power Block upgrade operation I have the following…

After talking to a Huma Air rep we discovered a strange think about my M3 and the upgrade kit.

The valve seat and o-ring (p/n 20860) that was missing from my upgrade kit should have been pre-installed in the valve house (p/n 20671-1) It was actually missing.

But in the weirdest way I did have the valve seat in my rifle. But how? 😳 The Valve seat was positioned over the Valve pin (Big Plenum complete assembly p/n 20275). But it should never have been in the rifle before I upgraded. How it got there is a complete mistery to me. I bought the rifle new in late 2021. And I have never disassembled the rifle as far as I needed too this time.

While stripping the rifle as far as I needed to do now I also noticed the Delrin bushing that’s on the end of the valve pin was a little ‘roughed up’. I could see the damage and scratches on the part. At that time I underestimated the significance of this part. Without this being in absolute pristine condition you’ll never get a sealed system.

The ease with which I could slide the valve seat over the bushing on the valve pin I could have concluded that it should not be assembled like this. I do think that this valve seat damaged the bushing but somehow kept the system airtight, but only just. I think the moment I took it apart some parts would be slightly different the next time I assembled it.

So after searching long and hard and with the help from Huma air, we now think we’ve solved the problem.

I bought a new complete valve pin assembly and Huma Air tossed a New valve seat in the order. I hope to get the package today or tomorrow. I’m very anxious putting it all together again and hope for a sealed and upgraded FX Impact M3.

Here’s the damaged valve pin bushing.

IMG_9736.jpeg


My biggest question now is how the hell did that powerblock valve seat find it’s way into my rifle? Is my rifle manufactured right at the split of fitting a Non-power block and installation of the so called ‘unmarked power block’?

IMG_9517.jpeg


Did FX use some leftovers and mix it up at different stages of assembling my rifle?

And why was the valve seat not pre-assembled in the Valve house of my power block upgrade kit? The Huma air rep told me that it happened before that the factory forgot to install it or even just toss it in the upgrade box.

I guess we’ll never know.

So, I hope I’ll have an upgraded and airtight Impact M3 at the end of this day.

Thanks for reading.
 
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Enkey said:
Hi
I have installed a powerblock on an M3.The M3 kit is reduced in the number of parts that compose it. I have to mount a new Valvehouse, Impact, Power Plenum part number fx 20671 in which the valve seat is included with a used part which is the valve part number fx 20275. The problem that causes me that combination of used part with new part is a small air leak, my intention is to rectify the valve and seat with the same technique that is used in the valves of the engines but before I would like to know your opinion or your experiences.
Regards
Enkey
Click to expand...
Hi Enkey, can u confirm the location of the small leak? There about 5 orings in the powerblock. The most commend is the valve seat oring not sealing against the valve housing due to poor machining, the bore for the valve seat is loose. The bore is over enlarged, the delrine seal on the valve rod is the wrong OD in relation to the valve seat ID size or damage. I would remove the barrel while there is pressure in the Plenum and apply leak tech inside the transfer port in vertical position and look for air bubbles. This way you're checking the valve seat oring and the Delran rod seal. if leaking to determine the actual leak location and course of repair.
 
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