Author Topic: Crosman 1400 Discharges When Pumping (Read 1879 times))

eeler1 · « **Reply #20 on:** January 15, 2024, 11:10:31 PM »

franken1400! Or as the doer probably called it, customized. That barrel/breech doesn’t look right with the tube. The tube shouldn’t be extended out behind the barrel, should it? Where does it say it’s a 1400?

You’ll get it sorted out. Make sure to post what you figure out about it.

avator · « **Reply #21 on:** January 16, 2024, 07:29:34 AM »

Looks like someone pulled a page out of my "tinker book". Every now and again I go through my spare parts drawers and take off bins and see what I have collected to build something out of. Often times screws, springs and seals are not factory. Sometimes the outcome is good and sometimes they just get broken back down to rise again someday.
Looks like someone tried to pass this one off on someone... hopefully not to be shady. I don't like shady.

Ascot500 · « **Reply #22 on:** January 16, 2024, 10:18:45 AM »

Keep in mind that with Crosman dump valves (130, 1300, 1400 some 760's) the sear's function is to hold the poppet forward.
It is being pushed rearward by the air pressure.
If the sear does not extend high enough catch the 140-017 sear block, then the poppet will blow off after one or two pumps.
It will also blow off if the sear is at a bad angle or is out of alingment - conditions that could be due to wrong parts.
In any case it should fairly easy to fix, even if the gun is a bitsa.
HMU if need more assistance - I have a 140 that I can use for pictures

Goose · « **Reply #23 on:** January 16, 2024, 11:53:35 AM »

That's an interesting rifle. The piston looks like one of the early Mac-1 jobs.

Here's a couple of pics of the trigger group. The trigger spring-tension is adjustable, so bumping it up some may cure the premature eacuation that it's having. The screw is at the bottom rear of the casting.

Luck,

J~

Starbright · « **Reply #24 on:** January 16, 2024, 12:24:38 PM »

I'll adjust the trigger screw after I get it near together. On the front, I plan on somehow putting a tube in the oversize hole of the plug and then a roll pin. I did drill out the screw beneath the bolt and plan on going to Ace Hardware in hope of finding a small screw to replace the one I drilled out. It's a Frankenstein. Reminds me, when I worked a the VA the admin desk gave me a paper of a patient with Frank N. Stein. I kept calling Frank Stein until I was exasperated and finally called Frank N. Stein and then I knew I'd been had. We all had a good laugh over that.

Starbright · « **Reply #25 on:** January 18, 2024, 12:53:57 PM »

The tube tip assembly (sight) had been drilled out to accommodate the larger pin and I can't find another assembly so I fabricated a smaller hole that may work temporarily until I can find the correct tube tip assembly. I took a 1/4" copper tubing and inserted it into the hole and the roll pin will fit within the copper shim. With oil, it should last quite a awhile.

Beaver Trapper · « **Reply #26 on:** January 18, 2024, 03:42:58 PM »

Your rifle needs a new trigger. I have had a couple that would fire after two or three pumps. New trigger solved that. The late Ron Sauls helped me through one I was having that issue with a long time ago.

Starbright · « **Reply #27 on:** January 18, 2024, 04:05:11 PM »

Quote from: Beaver Trapper on January 18, 2024, 03:42:58 PM

Your rifle needs a new trigger. I have had a couple that would fire after two or three pumps. New trigger solved that. The late Ron Sauls helped me through one I was having that issue with a long time ago.

Thanks for the advise! I'm expecting a barrel today and once I get this 1400/140/ etc together, I'll change out the trigger. Meanwhile, I'll look around for one.

Starbright · « **Reply #28 on:** January 19, 2024, 03:53:50 PM »

Starbright · « **Reply #29 on:** January 31, 2024, 10:56:36 AM »

Got the "1400" together with courtesy parts from members. I put a new quad seal (popped right in) in it and still couldn't pump up any pressure. Couldn't figure it out, all the seals were new except for the Mac piston head. So I changed that out to the Crosman and still couldn't pump. Then I took the Frankenstein apart yet again and then put another quad seal in, put the Mac piston back in and it pumped and holds pressure.
I'll post a photo of the "1400" tomorrow after letting it sit overnight with pressure.

Blowpipe Sam · « **Reply #30 on:** January 31, 2024, 11:35:51 AM »

Looking forward to those pictures.

Starbright · « **Reply #31 on:** January 31, 2024, 06:22:29 PM »

Here's a photo of the Frankenstein 1400, Ill post tomorrow if it holds pressure overnight.

. I adjusted the trigger and so far it doesn't fire when pumping.

Blowpipe Sam · « **Reply #32 on:** January 31, 2024, 07:25:29 PM »

Quote from: Starbright on January 31, 2024, 06:22:29 PM

Here's a photo of the Frankenstein 1400, Ill post tomorrow if it holds pressure overnight. . I adjusted the trigger and so far it doesn't fire when pumping.

Nice! It looks like a first model stock

Starbright · « **Reply #33 on:** February 01, 2024, 08:22:03 PM »

I can't figure it out, at one point the 1400 held air but not I pump it up to 4 strokes and come back in a couple of hours it has leaked out, no puff, nada. I have taken it apart 4-5 times and this time it will be 6 times, replaced the quad seal twice. I am wondering if it is the Mac pump or maybe I didn't oil it much when reassembling.
Perhaps the alcohol flush, I've never done that and to me it is a last resort because if all the seals are new it doesn't need alcohol. Any ideas?

avator · « **Reply #34 on:** February 01, 2024, 08:33:23 PM »

Here is a thread from back in 2017 that may or may not help you out.

https://www.gatewaytoairguns.org/GTA/index.php?topic=120571.msg1167970#msg1167970

Blowpipe Sam · « **Reply #35 on:** February 01, 2024, 09:02:39 PM »

Did you replace the check valve and check valve spring when you resealed the valve? The check valve can be installed backwards if you aren't careful. It might be a weak check valve spring or a distorted check valve.

Starbright · « **Reply #36 on:** February 01, 2024, 09:27:26 PM »

Sam, I put a little soapy water on the muzzle and the barrel is leaking air. I replaced the spring and the check valve. (the small white piece of plastic) I did a little studying or observation of the check valve and finally decided that the small end or tip should go in the spring but...I now think it's backwards #2 according to this photo:[i

. I'll fix it tomorrow AM.

Blowpipe Sam · « **Reply #37 on:** February 01, 2024, 09:46:50 PM »

If it's leaking out the barrel it's probably at the quad seal. Is the valve sealing cap flat on the surface that contacts the sear pin? Or does it have a distinct "step" to it.
I'm wondering if you got some 760 parts mixed in there too.

Starbright · « **Reply #38 on:** February 01, 2024, 10:23:43 PM »

I'm puzzled, what is the valve sealing cap flat on the surface that contacts the sear pin? I've looked at diagrams of the 1400 and it looks like and I may be wrong the trigger assembly? Dang, I hate to change the quad seal agin, it'll be the 3rd time. I have an extra seal kit that I can steal it out of and if that is the culprit, maybe it'll do the job of stopping the leak.

avator · « **Reply #39 on:** February 01, 2024, 10:27:11 PM »

The valve cap is the part that the quad seal goes into. The flat surface is the inside surface of the quad seal.

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Crosman 1400 Discharges When Pumping

Author Topic: Crosman 1400 Discharges When Pumping (Read 1879 times))