Crosman 101 reseal

Related Blogs:
Crosman 101 Disassembly

The valve in the 101 works the same way as the valve in the late model Crosman multi stroke pneumatic air guns, everything is just larger and less refined. 

I have the valve cleaned up and ready to be resealed. I purchased a reseal kit from Dennis Baker of Airgun Repair. The pump seal is at the top. The thick O-ring wont be used, some models had a groove for an O-ring to seal the valve body to the pump tube and this rifle doesn't have that groove. There were two check valve seals in this kit, I'm not sure if they all come with two or if it was a mistake. The thinner O-ring is to seal the exhaust valve to the body. A small tube of Pellgun oil is included in the kit.

The check valve unscrews so that the seal can be replaced. 

The seal was shot.

The exhaust valve doesn't look bad but I won't know for sure until I reassemble everything and test it. There were two styles of exhaust valve, the one pictured here and there was also a cone shaped (conical) seal. My other two 100 series air guns had the conical seal.

This is a picture of the valve from my 100 with its conical exhaust valve. There are a couple other differences, the spring is different and most of this valve is brass where the valve in my current project has some aluminum components mixed in. 

I laid out the parts to give a better idea of how everything works.

The brass valve body fits inside the pump tube, the pump tube is threaded and screws into the receiver. The aluminum exhaust valve seals against the brass body and is held in place by the nut that screws into the receiver.

The hammer assembly slips over the exhaust valve and the nut threads on to the end of the exhaust valve, the hammer spring is compressed against the nut when the cocking knob is pulled back. 

The face of the hammer assembly engages the sear and it is ready to fire. Clear as mud? Once you tear one apart it is pretty easy to understand how everything works.

It took a while to get all the old paint stripped off, I can see why people leave the brass exposed on their old Benjamins.... So Shiny!

Once the metal was all repainted and assembled, it is time to put the valve in. There is a paper/ fiber gasket that seals the valve to the pump tube. The gasket was showing its age and crumbled so I replaced it with a low tech replacement..... 

 Dental floss. I used this on my first 101 rebuild and it is still working.

Three or four wraps then push it up against the shoulder. 

Before installing the valve I applied some Crosman Pellgun oil to the floss the oil will soak into the floss and help seal it.

I used the exhaust valve and nut to install the valve body in the tube, tightening the nut until the body was seated.

With the valve body installed the check valve, spring guide and spring were dropped into the valve.

The exhaust valve was installed next, making sure it was lined up with the spring. 

There is an O-ring to seal the exhaust valve to the valve body.

Making sure the transfer port is oriented correctly  the exhaust valve is installed.

I used a drill bit to keep the transfer port oriented with the barrel and keep the exhaust valve from turning while the nut that holds the exhaust valve is tightened.

With the exhaust valve installed, the hammer assembly is next. The tube, spring and nut go on.

The cocking knob goes on last. The bolt needs to be installed before the knob. 

I left the trigger spring and guard off for the reassembly of the valve and hammer otherwise the sear gets in the way and could be damaged. With the valve and hammer installed the spring and guard can be re-installed

With the valve and hammer installed it was time to adjust the pump length. 

Since I was going to be removing the pump several times to get the length adjusted I used a 3/16" drill bit for the linkage to pivot on. 

I stopped here, the end of the pump is hitting the valve at this point. With a little more pressure the pump handle closes tight against the pump tube and stays in place. Zero dead space between the pump and valve is what I was going for. Once I was satisfied with the pump adjustment I pulled out the pump assembly and tightened the jamb nuts to lock everything in place.

With the pump linkage adjusted and everything tightened down I installed the pivot pin, notice the recess in the pin and the dimple in the spring clip.These need to be oriented correctly to hold the pin in place.The paint got dinged up during assembly, if I had let the paint cure before assembling it there would have been less damage. I'll have to do some touch up to the paint once I'm sure it is ready for final assembly.

Everything is working great so far, it pumps up and fires. On this rifle there is enough spring pressure on the hammer spring to hold the exhaust valve open, so the hammer needs to be cocked before pumping up the rifle, otherwise the air goes straight out the barrel with each pump stroke. 

I did notice an air leak, I could feel a puff air on my forehead every time I fired the gun. I put a barrel cleaning patch on top of the bolt and fired it to verify what I suspected, and sure enough the patch was blown off the bolt, verifying that it was leaking between the bolt and the breech. During the initial tear down the breach got dinged up while removing the barrel from the receiver. I had cleaned up the breech in the lathe and thought I had a good fit between the bolt and breech, it needed a little more work to get a good seal. To fix this leak I applied some automotive valve grinding compound on the face of the bolt, installed the bolt and rotated the bolt back and forth against the breech to lap the bolt to the breech. Lapping the bolt cured the leak and everything is coming together now. 

UPDATE:

I shot a string across the Chrony tonight, a 10 shot string with 14.3 grain Crosman Premier Hollow Points gave some great results. With four pumps for each shot I was getting an average of 475 fps. The impressive thing is the extreme spread was 5.4 fps and the standard deviation was 1.73 fps. Great numbers from an old air gun. Six pumps gives 550 fps and eight pumps gives 600 fps, again good velocities for an old pumper.  

I'm not getting the accuracy I was hoping for. My first groups looked like shot gun patterns, I was checking the crown and noticed paint inside the muzzle. I had plugged the barrel with a pellet before I painted it but some paint still got into the bore. With the paint cleaned out and another barrel cleaning the groups got better but still over an inch at 10 yards, good enough for shooting cans but not what I was hoping for. I'm going to spend more time with it before I do anything drastic....