Crosman Challenger PCP target rifle.
How we fix them today (Part 1 to this report)
This report covers:
- Not for beginners
- HOWEVER
- Smashed transfer port seal
- Disassembly went quick
- Assembly
- The BIG one!
- Cocking handle disassembled
- Transfer port seal
- Leak test
- Bottom line
Today I reseal the Crosman Challenger precharged pneumatic (PCP) target rifle. I followed the video I linked to in Part One of this report. My computer sat on a table next to my work bench and I followed the steps shown in the video exactly. Most of them were straightforward, but there were a couple hangups and what I thought might be a one-hour job took four!
Not for beginners
I said in Part 1 this looked like an easy job that anyone could do. But I forgot about the edit feature in video software. For most of the steps things went exactly as described and I fast-forwarded to the next steps. However — there were some things that I found challenging, and I will now recant and withdraw my statement that anyone can do this. Maybe some very handy people can do it the first time, but I wouldn’t recommend this for beginners.
HOWEVER
The first departure from the video is minor. The presenter, Colby Sakumoto, tells you to use a wooden dowel to push parts out of the reservoir tube, but he doesn’t give the size. I measured the outside of the tube and then bought a 3/4-inch dowel and a 5/8-inch dowel. The 3/4-inch ALMOST fit, but not quite. Get a 5/8-inch dowel or one that is close to 15.875 mm. It has plenty of clearance inside the tube.
Smashed transfer port seal
I discovered that the transfer port seal in my rifle was smashed just like the one in the video. That probably happens when the receiver and reservoir tube are together and nothing can be done for it. Just have a spare seal in case you need it.
The transfer port seal was smashed.
Disassembly went quick
The disassembly went quick and followed the video perfectly. I drilled a hole in the end of the 5/8-inch dowel rod and it worked perfectly for disassembly. I had the rifle apart in about 15 minutes.
Following that I cleaned the inside of the air reservoir tube. I followed the video instructions exactly and it took just three push-throughs of a rag soaked in alcohol to clean the inside of the tube. I was ready to assemble the rifle.
Assembly
Now it was time to put everything back together. I put Super Lube oil on all the seals and o-rings as I assembled things. I won’t mention it again; just know that it happened.
The BIG one!
I think this is the biggest help I can give you if you undertake this job. I may be wrong and if so I apologize, but please consider what I am about to say.
You will remember that I bought a new firing valve and a new inlet valve from Archer Airguns, because they saved me many hours of work. Stephen Archer told me he always uses new valve assemblies for his repairs, so I guess the old days of resurfacing valve seats are over. Hooray!
Both assemblies came with o-rings installed. But when I slid the new firing valve into the reservoir, both of its o-rings were cut on the many openings. Colby has you slide these parts in from the trigger end of the tube and that’s where all the holes with sharp edges are. When a ring gets to a hole it bulges out just slightly, and the sharp edge of the hole cuts it.
The sharp edges of the holes in the reservoir tube on the trigger end ruined three sets of firing valve o-rings.
In the photo I show you just one of the damaged o-rings — the one that was damaged the most. Most of them were damaged less, but they were still ruined for the job. Looking at the photo you may wonder why I didn’t just use a tool to prevent the damage. Well I’m just showing one hole. There are many on the trigger end of the reservoir tube. I could feel no burrs on any of the holes, but they obviously sliced the o-rings effectively.
After ruining three sets of o-rings doing it Colby’s way I wondered what would happen if I slid the firing valve in from the other end of the reservoir tube — the fill nipple end. There is only one hole to watch going that way — the pressure gauge hole. It almost worked, but I did slice a small sliver of each o-ring. Then I remembered that I bought a tool specifically made to protect the o-rings from this one hole that is the largest in the tube. On the second attempt I got the valve in place with no damage to either of the rings.
Remember this guy? It goes over the pressure gauge hole. Use it and slide the firing valve in from the front of the reservoir tube. No o-rings will be damaged.
I initially thought buying two sets of o-rings for this overhaul was wasteful, but it wasn’t.
I went through a lot of o-rings before I changed my approach.
After that the rest of the assembly went pretty well. I did clean the barrel, but only because it easy to do.
Cocking handle disassembled
I didn’t intend to disassemble the cocking handle, but I did it by accident. That made me fast-forward to the place where the video shows how to disassemble, clean and assemble the handle again.
Ooops! The cocking handle disassembled itself, so I had to clean it and assemble it again.
Transfer port seal
The only other difficult step was replacing the air transfer port seal. I discovered that you just have to put it where it goes and squeeze the two parts (receiver and reservoir tube) together until you have them connected with a screw. This seal is probably going to be damaged every time the rifle is assembled.
Leak test
Once the reservoir was assembled I filled it with the G9 hand pump and leak tested it just as shown in the video. By this time I had been working on the rifle for three hours in a 95-degree F (35 degree C) garage, and I was getting confused and tired. However, to my utter surprise, the reservoir was sealed!
The remainder of the assembly took another hour, with the cocking handle being an interesting 15-minute diversion. Then I filled the rifle to 2000 psi and was finished.
Bottom line
The bottom line is — this rifle is now sealed and ready to go! Two days after filling it was still holding all the air. I will test the velocity and adjust it if needed in the next report. Four hours in 95-degree heat is enough for this old man!
I have to say that Colby’s video is great. He even shows things like assembling the cocking handle, which I turned out to need. With the exceptions that I noted, his video is a wonderful guide!
B.B.
Other than wooden dowel rods and your O-ring saver, what other tools did you use? Did you need hollow ground screw drivers?
Could you not sand/file the holes so the leading edge is slightly rounded? Seems we all should order tons of O-rings.
-Y
PS how did you know when the o-rings were cut?
Yogi,
I used the same tools that Colby used in the video. No- I won’t sand any holes in the reservoir tube.
The o-rings have small cuts on their outer edges. I know because I saw them. I showed the worst one, but I have photos of others that have tiny pieces of o-ring shaved off.
You won’t need tons of o-rings if you do the work the way I explained in this report.
BB
Yogi,
by filing/sanding a hole’s edge in a reservoir tube, it is very possible to introduce a point where a leak will develop.
Tom,
I would have imagined that the valve cannot be loosened then tightened in place to expand the O-ring. That’s what we have with our valve rebuilds in our local version of the Crosman 160.
Siraniko
Siraniko,
The o-rings are not in places where tightening and loosening the valve body has any effect.
BB
Enduring 4 hours of frustration at 95 degrees Fah wouldn’t be possible unless it is either fun or a life or death event. I know it is not a suitable task for my herky jerky, arthritic and impatient fingers.
BB deserves our thanks for showing us why this job should not be attempted by amateurs. I do enjoy reading how it’s done by those who have the gift.
Deck
I am one of those who enjoys taking things apart and putting them back together. I began building models as a wee bairn. I have always been curious about how things work.
Airguns are really quite simple machines, although sproingers are a bit more complicated in their operation than many realize.
Air is made of itty bitty teenie tiny little particles that can be quite difficult to contain. It took many years of trial and error to figure out how it is done. There are no real shortcuts in keeping that air in one place. You have to plug up all the little holes it will find to let itself out. If you cut or tear a hole plugger (o-ring, seal, etcetera) the air will go through that opening into the big, wide world. Many times, it will hiss at you in amusement.
Sometimes it will ease itself out over a period of time, not letting you know that it is getting away or where it is doing such. That is when the hole is real fun to find. Sometimes you never find it.
You are among good company that includes BB, Gunfun1 and others who comment here. It is written that Abe Lincoln took everything apart and back together to see how they worked.
Deck
RR,
Sometimes air (and even CO2) will leak through porous metal airgun castings.
BB
BB,
Not much nowadays. Do you think some silicon oil would help that? It can work pretty good with o-rings.
RR,
I doubt it. I think Ian knows for sure.
BB
RR,
I too am blessed (cursed?) with an overactive curiosity of how things work. Coupled with a career working with engineers who are compelled the improve things that are fine as is and fix things that are not broken, I’m guilty of getting into mechanical binds that could have easily been avoided. BUT, there’s that satisfaction of figuring it out. 🙂
At a very young age, my curiosity almost cost me my life. My uncle had stored his brand new Harley Davidson motorcycle in the garage for the winter. Bored from being stuck inside, I took it on myself to remove whatever fasteners (and parts) that I was strong enough loosen… he was a “little” upset. Fortunately, I had kept all the together in separate trays and reassembly was not to painful (for my uncle) but I recall that sitting was uncomfortable for a while.
Obviously, that experience didn’t cure me LOL!
Cheers!
I have not been able to sit at times either. I was not cured.
Seems it requires the patience of Job to do this job, BB. And in those temperatures…but you’re the man! FM had watched the video in its entirety, and while it is indeed very good and all the rebuild steps are clearly shown, he decided this was a task above his pay grade.
I just watched the video. That’s a good one. Thanks!
My limited experience with the newer model 2021 Crosman Challenger shows me that it has a different valve. The newer valve has a velocity adjustment screw built into the valve. It is 23g (part #1763A028) in the photo of the diagram below. That’s the screw that I was referring to in my comment in part one of this series (that was apparently slightly undersized and kept working its way back into the valve and reducing the velocity). The set screw 23h keeps that velocity adjustment screw from backing out of the valve. But apparently it does not prevent the adjustment screw from working its way back into the valve. The newer model also has a pressure regulator that is designed to increase velocity and accuracy consistency.
Elmer,
I am not sure, but that looks like the Marauder valve to me.
Yes, that wouldn’t surprise me. I have been told that it uses the Marauder trigger. But I am not familiar with the Marauder. The service center technician had never serviced one of the newer model Challenger rifles before. But he seemed to know what to do with that valve. He just didn’t figure out that the velocity adjustment screw was apparently slightly small. I think he would have if he had shot it enough times for the velocity to get low enough to be obvious. He did check it with a chronograph. But only shot it a few times before declaring it repaired and sending it back to me. Once I had adjusted it myself and watched the velocity drop again it seemed obvious to me that the velocity adjustment screw was working itself back into the valve on its own. But I didn’t know why. Crosman just replaced the screw according to the paperwork they included. It has been great since then.
Elmer Fudd,
I looked into your Challenger CH2021 to try to find an EVP (PARTS LIST & Exploded Diagrams). Crossman doesn’t have one listed and no other sources were found in a search.
The CH2009 II is Discovery based with the pressure tube size and the EVP for that model clearly shows a Marauder Trigger group.
I that the 3,000psi will say pressure tube looks like it came off of a Marauder Rifle and the valve looks outwardly like a regular Marauder valve. The Part Number however says their is something different about the assembly. That could be an internal volume reducer, spring rate changes, Transfer Port size change…who knows.
I would suspect an incorrect TP restrictor screw was installed from a less than careful assemblers parts bin.
Glad it works now.
Gives me some ideas on a HOT CH2021!
shootski
shootski,
I learned how to make an AirForce Edge a little hotter (~700 FPS) and give it an excellent trigger and allow it to be returned to stock.
RidgeRunner,
Didn’t Tom wind up with that one?
You should get it back for you and and/or your nephew!
shootski
Yes, he did. I am trying to get it back from him. The trade we made was a good one, but I really do miss that air rifle.
Elmer,
The Marauder/Armada valve has a transfer port adjustment under a screw plug as is shown in the picture. I could see where the longer screw was to work itself down into the valve it would most definitely drop the velocities as it would reduce the size of the transfer port.
Yes, I believe that is what happened to this rifle. I have an exploded view/parts list for the CH2021. If I remember correctly it may have been emailed to me from their tech support. If you want one I will try to find the email. Just let me know.
Elmer,
Please do. I would really like to have that.
Okay, I have found it. I just need a way to send you the pdf. Please let me know. Thanks.
Send it here:
burke93 at tds dot net
I think you know what to do with this.
Yes, it has been sent. Please let me know if any problems. Thanks.
No problem. Thanks!
BB,
Some design situations (odd mating surfaces or difficult assemblies) use a sacrificial o-ring that needs to be replaced every time. Most o-rings live long and happy lives.
I have collected a box full of various o-ring tools (dowels, rods, bits of pipe) shaped to keep the o-ring depressed or in place during assembly.
I wouldn’t file or sand the edge of a hole threatening and o-ring but a tiny bit of polishing (0.005 inch) to remove a burr is often helpful. I use a Q-tip to detect rough edges.
Hank
When I had to re-seal my Marauder, I, too ruined several seals trying to push the popit valve assembly in from the trigger side of the compression tube and from the muzzle side as well, even trying to depress the O rings with my finger to pass the openning in the tube. I then took my dremel with a triangular grinding bit and ground down the inside edges of all the holes, including the air gage hole and then slid everything in from the muzzle side. Only one hole to get by and my machining worked just fine. The air filler valve threads didn’t seem to damage the o rings. Right now, it holds air just fine and is the “go to” squirrel gun when they get too intimate with the bird feeder.
On another topic, does anyone know what make and model air rifles and pistols took medals in the Olympics? Very curious as to what China competitors used.
On another topic, BB – what is the matter with you? Working in a garage in Texas that’s 95 deg? That’s what kitchen tables are for!!! OK, use a cloth if you have to 🙂
Fred formerly of the Demokratik Peeples Republik of NJ now happily in GA
RidgeRunner,
The parts diagram is labeled: CH2021-002
Looks nothing like my Discovery valve.
But the TP restrictor looks like the Pistol Marauder’s.
shootski
Just a note.
Back before I retired and throughout time when I worked on hydraulics at work I used a small flat head screwdriver that I rounded off all the sharp edges then polished them.
That was used to push the orings and lip seals below a tube opening when assembling. Most of the time we didn’t have the option to assemble from another direction. Also we used hydraulic fluid in those opening when pushing the o-ring past.
In the case of a air gun, especially a pcp I would use silicone oil.
Just remember go slow and easy and pay attention to your seal or o-ring and push it below the opening with a non sharp object as your pushing past the opening.
Have fun you all shooting. Keep it safe and teach the young’ns every chance you get. 🙂
GF1,
If there was just one hole per operation that would be possible. This tube has three holes at the same point around the tube and the two o-rings have to pass all of them at the same time.
Add to that the valve body, even with a liberal coat of o-sing Super Lube, is wedged in the tube by the o-rings expanding outward, so the valve body has to be tapped through ther tube with the dowel rod to make it move.
BB
BB
Can’t count how many Discovery, Maximus and Marauder valves and gauge port blocks I have put in from what I will now call the wrong way or the other way.
And yes just like at work. The o-rings are passing past holes at multiple places at multiple times.
Yes us air gunners are like jewelers making watches when we are assembling our air guns at certain times.
Got to pay attention to all aspects always.