Friday, February 20, 2009

Derrick's on a Beeman P17 Overhaul, Part 1

Buddy Jason recently sent me his Beeman P17 for the spa treatment. Since I've had quite a few email queries about the P17, I thought a tear down and rebuild illustration guide might be worthwhile. T.W. Chambers & Co. has a great schematic of the Beeman P3 that we can use as a reference point here. Keep in mind that the P17 is a Chinese sanctioned copy of the German Beeman/Weihrauch P3.

Unlatch the pseudo hammer and open the gun as though cocking. With the gun open, use a 2mm allen wrench and loosen the set screw as shown. It's unnecessary to remove the setscrew, just back it out a turn or two so it's no longer bearing against the cross pin. Drift out the cross pin.

Pull the entire piston right out of the compression tube.

This step is completely unnecessary for a routine tear down. I'm going to crown the barrel on this gun as I get further along. I removed one of the small e-clips on the barrel pivot pin and using a drift, pushed the pin out.

Another view. You can see the small e-clip just above and left of the cotton swab.

Using a 2.5mm allen wrench, remove the right side grip panel. Find the seam on the bottom with a fingernail and gently separate. Some of the internal pivot pins may stay attached to inside of the right grip. That's OK. Note their location and pull them out of the grip. Try to not scar them up with pliers.

Using a small pair of needle-nosed pliers, pop the tails of the 2 springs out of the left grip panel to relax the spring tensions.

Pull the pivot pin out until it just clears the mounting hole and remove the sear straight back and out.

Another view. Holding the sear. Pull it straight out.

Unhook the torsion spring from the part that looks like the number 7. Weihrauch refers to this part as the true "hammer".

Remove the hammer's torsion spring.

Unhook the lower end of the coil spring attached to the pivoting lever on the hammer assembly.

Another view.

Next, unhook the top of the coil spring from the pivoting lever . Set the spring aside. Pull the hammer's axis pin out slightly and rotate the hammer assembly as shown on the valve stem and it will lift right out.

Here's the #7 looking hammer assembly. The pivoting piece at the top is the lever. Coil spring shown detached but oriented correctly. Upper loop of the spring fits into the round hole in the lever.

Removing the hammer axis pin shows there's yet ANOTHER spring inside the hammer. Note the orientation of the loop.

I pulled the trigger axis pin and the trigger came right out.
More to come.

34 comments:

Anonymous said...

Simply AWESOME Derrick!!!!!

Jason

Anonymous said...

Derrick - THis is awesome! I have a P17 which doesn't fire unless I pull the trigger a few times. Any idea what that might be? Hopefully I don't have to do everything in your guide...the gun is only 1 month old and has been fired less than 100 times.

derrick38 said...

Hmmm...Did you adjust the trigger set screw inward too far? There are several potential problems. Perhaps the safety is sticking...Or it could be the trigger/sear connection...Or the sear/valve stem... At a month old, the gun should still be under warranty. I'd be tempted to return it and get another. Why return? Well, there are exactly zero repair parts for this gun. So, if a component is broken you'll have to manufacture any and all parts needed.

Bill said...

Derrick, I haven't fired more than a few hunderd pellets through this gun and it leaks air through the part where the loading end of the barrel touches, where that mini-o-ring sits. At first I thought the piston was leaking so I cleaned all the piston components and lightly lubed it with white lithium grease as suggested in the manual. When I push to close it, I can hear air hissing out through this hole. My guess is there is another seal leaking air between the piston and the loading end of the barrel. Any suggestions? I've had the gun for 18 months.

derrick38 said...

Bill,
Really sounds like the valve stem o-rings needs some attention. Check the final installment on the P17 here:
http://anotherairgunblog.blogspot.com/2009/02/derricks-beeman-p17-overhaul-finale.html
This should walk you through the disassembly/reassembly.
Derrick

derrick38 said...

Bill,

The address I posted might be truncated by the blogger software. Go to our blog index on the right and scroll down to post number 180.

You can also use the search function on the blog at the very top left corner. Type in " P17 " and you'll get all 4 posts for the gun.

Derrick

Bill said...

Derrick, Thank you very much. That seems to have done the trick.

Bill

Anonymous said...

When i heard air hissing out of mine, i completely tore it apart looking for a faulty/ brittle o-ring thinking that the grease they slapped in there, might have destroyed the o-ring over time. After finding nothing i took the rifled barrel out and moved it aft about 1/64" inch and the hissing stopped. Either the barrel gets pushed slightly forward from the o-ring after cocking the gun for a while, or the o-ring itself flattens out. Anyways, had a nice crack in the housing so i returned it...not 200 shots later my new P17 won't fire at all.

Kort said...

Derrick, Can you post the O Ring sizes for the P17. I have one that is leaking and have torn it down cleaned and put back together but the leaks persist so I'd like to replace all O Rings.

Thanks
for the detailed posts

derrick38 said...

Kort,

O-ring sizes: It's been too long and it looks like I never wrote it down. Sorry about that. Happens sometimes as I'm trying to fix the thing and then I remember I'm gonna write it up, too.

I've got several o-ring kits so I just root around until I find what I need. It's easier and cheaper than driving back and forth to the hardware store. They're often under $10 for a kit if you have a Harbor Freight nearby.

derrick38 said...

O-ring update:

Opened the gun back up. Piston seals are size #116. Uppermost seal on the valve stem is a #006. Hope that helps. I'll add this to the text.

Tom said...

Thanks for this awesome series of posts.

I just bought a P17 and it worked great for about 50 shots and then the valve started leaking.

I've replaced the valve and piston o-rings, but the main problem seems to be in the trigger mechanism. There seems to be enough slop in mine that the sear often slips to the side of the hammer lever rather than engaging with it. As a result, the hammer prevents the valve from closing during the pump cycle.

Any suggestions for making the sear engage more reliably with the lever?

Thanks again,
Tom

Chris S. said...

Thanks, Derrick, for the great pictorial. My P17 starting leaking after less than 1K pellets. I'm still trying to find the leak as it doesn't appear to be from the hammer, sear, or a loose stem nut. Probably an O-ring.

derrick38 said...

Tom,

If you're having problems after only 50 shots, just take it back and get a new one.

The V-shaped hammer spring needs to have the rear end of the spring in the RIGHT side half of the grip on reassembly. Hammer spring is Weihrauch part number CS387.

http://www.gunspares.co.uk/shopdisplayproducts.asp?id=24763&cat=P3

Tom said...

Thanks, Derrick.

I thought about returning the gun, but I had to file a bunch of registration paperwork (for a pellet gun!) and figured it would be too much of a hassle to update the serial numbers and stuff for a $40 gun.

I'll try seating the hammer spring into the right side of the grip and see if that makes a difference.

Tom said...

Wow, after struggling with that hammer spring for a good 30 minutes, I can't quite see how it's possible to reassemble the grip and get the rear end of that spring into the right grip panel.

Any suggestions?

derrick38 said...

Tom,

Yes, leave the hammer spring sticking out the back as you start to install the right side cover. Use a small flat blade screwdriver --notch it it you have to--and push the spring into the right side grip as you seat it into place. Install the grip bolt and you're done.

Anonymous said...

Hi Derrick,
I just finished changing the 006 O'ring on the valve of my NEW p17.
Thanks to your great photos and instructions I believe it was a success. Time will tell. Thank you so much for your blog.
Ken

Anonymous said...

do you know where i can buy the #7 hammer

SifuSun said...

To everyone that said their p17 is dumping air after you cock it, Let me say I solved that problem on mine. After about 100 shots it started to dump air. So, I took off right side pistol grip to access air valve plunger connected to trigger assembly. All i did was to spray a liberal amount of wd-40 on the valve stem post and work the cocking mechanism back and forth a few times. This lubed the seals in the valve which I guess became dry with use. And wallah, she holds all the air and shots great.

Pascal Cadorette said...

Hello there!
I also have a Beeman P17 which is 2-3 years old. The problem I have now is that the pression of the air is leaking, so either there's not enough air to shoot or the velocity is very low. If shot it around a 100 times and now I have this problem :/.
I suspect the air chamber, but that also might be the seal the trigger that might be the problem.
Do you have any ideas?
Thank you :)!

Shane Renolds said...

Anonymous said...

If anyone wants to buy my broken P17 (releases air on closing stroke), I am willing to sell it for parts or for refurbishing.
Email me at cobbs.zhang@gmail.com

Anonymous said...

Whenever I have air leak on my p17 I usually do the following to correct it:
1. add oil in breech valve and cylinder.
2. replace cylinder o-ring with green A116.
3. remove grip cover and tighten end bolt of valve stem assembly.
4. If still no go, replace all the o-rings inside the valve stem assembly.

It has happened to me at least 20 times a year and each time I use the above procedure to correct the problem.

Xi Mu Xiu said...

In order for your P17 to be able to cock , It has to have a click sound shortly after you start closing the cylinder. Otherwise the P17 will not be able to fire. So all the corrections and adjustments mentioned before are intent to bring back this click sound......p.s.

Xi Mu Xiu said...

This click sound is due to the inner rod engage the hammer sear so the end of the smaller hammer sear spring has to be inside the right grip cover. Over the time this spring end might get to the left hand side of grip cover and you will not have this click sound and hence P17 can not be cocked.....P.S.

Anonymous said...

Procedure to remove valve stem assembly without disturbing the hammer sear system.
1. remove piston pin.
2. remove grip cover.
3. use something to block hammer.
4. remove valve stem end nut.
5. remove piston receiver pin and lift piston receiver.
6. overhaul valve stem assembly described previously.
7. install finished valve stem assembly onto piston receiver without end nut.
8. install piston receiver onto pistol frame.
9. put end nut back to valve stem assembly and tighten it.
10. put grip cover back on and check for operation.


Anonymous said...

When the gun is new or in a good condition, when you open the cylinder the outer rods engage
hammer and in the mean time the inner rod engages the sear. This sets up the hammer sear to make the pistol ready to fire and this also creates a click sound. Without this sound
all the air inside the cylinder will be dumped by hammer at the end of stroke. One easy way to correct this problem is to add oil to hammer sear system.....p.s.

Anonymous said...

If your gun gets old (about a year old) and you have hammer or sear problems such as air being
dumped by hammer at end of cylinder closing stroke. Be sure to leave the end of hammer spring (largest one) inside of Right Grip Cover. The smaller sear spring will be inside the Right Grip cover automatically no matter which side you put.
Derrick said it is the binding of hammer spring causing the problem. I am not sure about that.
I only know it did solve the air dumping problem for me though. So watch that hammer spring!

PassionatelyPatriotic said...

I must be very lucky. I have had my P17 for almost 3 years and have fired over 4,500 pellets throughout it. I kept the empty tins to keep track of how much shooting I was doing. Last night I had my first failure. I noticed recently that on occasion it would take a couple of attempts at opening the gun very quickly to get it to draw in air to be compressed. Then last night, I loaded a pellet, closed the housing which had normal resistance, and pulled the trigger. Nothing but a click. Then the trigger would not "click" again. After much effort, I got the top opened, cocked it again, and this time it fired. During the remaining 300 shots, it malfunctioned this way about 5 more times. Guess I'm going to had to take it apart to see what is wrong. BTW, I really like this gun. I also have a Beeman Temptest and a Crosman multi pump pistol. I prefer the P17 for feel, accuracy and sight picture.

Anonymous said...

Whenever you have dumping air at end cocking stroke problem on your P17. Do the
following to correct it:

1. Check and replace all 4 o-rings especially small M006 at end of valve stem.
2. Place a washer over the main spring.
3. or Place main spring leg inside right grip cover.
4. Work cylinder back and forth to get that click sound back.
5. add some oil in the breech valve hole.

P17 is not that bad . What you expect from a $ 30 gun? At least it makes me an air
gun gunsmith. I bought this gun 3 years ago and I can make it work forever. That
is good enough for me!

Anonymous said...

so I thought I would add my experience with the p17 I also had a problem right about a month old so fairly new, the trigger wouldn't fire the gun all the time, having to pull it a few times and eventually it would go, I found this quite alarming. The gun being so new and also quite a dangerous problem to have. So I went online and I forgot whos video I watched but its really a simple fix. you start by removing the one side of the handle, with all the trigger mechanism in it, the very first spring that you will be dealing with, as you remove the plastic handle is the "Hammer" spring as he calls is in this post. the problem I think is this spring can slide inside the handle where tension is made. What I did to fix this was first stretched the spring a little, (this is personal preference for added security) then mainly you need to look at how the spring should sit under tension, (I used tape, some kind of glue would work) without having the plastic handle screwed down and in place yet. once all secured and you see trigger is catching each time you open and extend the lever, finally screw the black plastic handle back in place and you should never have a problem again.


hope this helps anyone

Oscar Cheng said...

I lost the bolt that is under the optic sight at the gun range. Now it just hangs loosely. Does anyone know which nut is used for that? Thanks.

derrick38 said...

The rear sight is held with a 4mm x 0.7mm bolt and nut.