A couple of problems after 140 reseal

[newt68]

I picked up my first 140 and resealed it yesterday and also installed a Mac1 flat head piston.  After the reseal I have two issues.  First issue is I can only physically pump it 5 or 6 times.  It is nearly impossible to pump it more than that.  Is that normal?

Second is the more common air leak.  It will only hold pressure for a few minutes.

In terms of the air leak, I cleaned all the parts real well in an ultrasonic cleaner before reassembly and installed the new seals including the quad seal and the O-ring on the brass check valve.  Any troubleshooting tricks to determine where the air leak is coming from?

I have also swapped out the brass check valve for a white (teflon?) one I had from a Crosman 760 I had.  It still leaked after that as well.

[Back_Roads]

 Hard to pump after about 5 means the pump is working just fine, they are a bit difficult to pump past that if working. as far as the leak the white disk may need to be tapped in to get a set, that or they have a sealing side and a rough side, some suppliers mark one side with an X. other than that oring seal on the valve

[newt68]

Ok great to know on the 5 pumps!  I plan on going over everything in the valve again later and will try tapping to set the check valve.

Thanks

[Duane38]

One thing to check is the lever toggle pivot.  If the hole is elongated/out of round, the toggle pin rivet rides in a way that binding occurs.  Found this to be the case on a few I've repaired over the years.

Though, not the greatest lever design for mechanical advantage, the piston size shouldn't make it too difficult to pump to 8 or 10 pumps.  Stout, yes.  Not nearly impossible. 

[newt68]

The pivot point looks good.  I did do a bit of a deep clean on the valve around where the check valve seats so will see if that fixes the leak issue.

Currently, I have everything apart and started to strip the stock and forend for refinishing.  I will report back on both issues once everything is back together.

[newt68]

I reached out to Tim from Mac1 and he told me that because the flat head piston moves more air than the stock pump cup, 6 pumps would be the max now.  So with that behind me the only issue left is my air leak.  I will update this thread once I have the gun back together in a few days after I have finished refinishing the wood.

[threesuns]

Any chance the check valve is the culprit? Could contribute to harder pumping.
Your flat head piston is designed for pumping but should not be have to do the work of the check valve also.

[newt68]

I think it could be a problem especially with the air leak.  I did take the valve apart again and found it needed a better cleaning around the check valve area.  Once I get the gun back together I will post my findings.  I do have the original brass check valve with an O-ring and a white Teflon one from another project.  I am hoping one of these work to correct the air leak and like you said potentially it has something to do with the hard pumping.

[c801tfd]

The 140, 147 and 1400 all become harder with each pump and Like Tim said 6 pumps is about max with the flat head piston as it is more efficient at moving air into the valve. The “Pop Off Valve” design of these rifles also affects trigger pull as the more you pump the harder the trigger pull gets, this is normal and the beauty of the design is it resolved the valve lock issue found in the 110 and 120 models.

As for the check valve it sounds like it is cleaned well enough for a good seating/seal. I learned the hard way about the metal one with o-ring was good but would leak. I found By searching numerous internet threads that it recommended to use the white modern replacement, and that proper sealing occurred by replaceing the old check valve spring with a new one that depending on the kit you purchased should have one in it as well, I know the Baker, Mac-1, Precision Pellet and the Crosman600 kits do have spring replacements.

I hope your project is a success, it’s fun to get these oldies up and running like they should.

[newt68]

Great information thanks!  I am using an the old spring so maybe I should consider swapping that out. 

Beautiful guns as well!  I will post a picture once it is back together.

[LOKEY]

I don't know? Sounds odd to me. After I resealed my 140 it holds air just fine and I can pump it 20 times if I want. I don't do that but I did it one time just t see if it would handle it.

[TF89]

One way to get the check valve to seal is to cut a piece of 3/8 wood dowel just long enough so that you can screw the valve together with check valve in place overnight.  This will form fit the check valve.  This is what I do at it has worked everytime,

[Pelle]

  I had a lousy time on mine a couple years back with some made up tricks and it goes to 20 with no trouble and has serious power and easy pumping with less. I bought the kit and my original problem of dumping gas when pumping persisted but seems better now. It would leak but then work fine.

[newt68]

The wood took some time to refinish but the rifle is back together again.  A new Teflon check valve and spring fixed the leak.  It still maxes out around 6 pumps but I think that is because of the Mac1 piston.

[threesuns]

very nice. I like the spoon handle!

[c801tfd]

Glen,

Great to see it up and running again, 6 pumps seems resonable as the Mac1 flat top piston is more efficient at moving air. I know 6 is good enough for me but 8 is doable I just dont like stressing the linkage to force more air when just punching paper.