Tuning STUCK halfway thru' Seneca Aspen/Nova Freedom Pump Repair - PHOTOS

[Null_Pointer]

Thanks for the warning about the pressure tube. Had no idea it was still charged to 1800 PSI. Scary!

Pictures are a good idea. So..... as a reminder I am trying to fix a leak, but I don't really know where it is.

This is a picture of Butch's probe side by side with mine (on the right). Is this where the 006 o-ring(s) goes? Mine is a flat ring, and it seems in OK condition. Perhaps this is a design change in later versions. I presume I could change it for a couple of the 006 buna rings. (??) So, I think I will assume this is not the source of the leak.

Therefore, I assume I need to access this part to clean it and replace any bad seals:

In order to get to it, do I need to unscrew this (pic from sticman77 above):

And if this is the case, will it take a lot of torque? I already tried once and could not budge it. Maybe I need a cheater bar? 

 

[Butch]

To get to the check balls you must unscrew (CCW) the center piece withe the 4 hole. It holds the black piece down. After unscrewing the center (silver) piece, slide the black piece off. Then you will use a wrench to remove the tube to get to the check balls and seals. 
hope this helps you out. 
Butch

 

[Null_Pointer]

Thanks Butch, this makes it clear. 

On my gun, the "silver" central part is painted black, and there are only two holes, and they are only 2mm diameter (small).

What's really bad, is that the silver part appears to be aluminum, and the shaft going through it is stainless steel. That unfortunately, is a recipe for corrosion, and I can see at the interface between the two that this has already started. There's a white powder at the interface that indicates corrosion has started. There are not really any solvents or lubricants that can fix this.

As a result, I have not been able to apply enough torque to get the silver part to move. I will keep trying.....

 

[cegd]

I would like to ask for some help as I also realized that it only takes me 15 pumps to get the gauge from 0-3600! That’s seams Way too little as I read people taking about 75 strokes to get it to 3600!

Also weird is that I only get 3-4 shots from 3600-1000psi, on low power and 2 shots from 3600-1000psi on high power! this is confirmed by the fact it takes me 5 strokes after each shot to get back to 3600 on high power and about 2-3 strokes on low power. im so confused as this .25 Aspen is suppose to see 9-11 decent shots on high power and 15-17 shots on low power! 

Could I have a faulty gauge? Could it be that the previous owner adjusted the hammer spring (I don’t understand the function of adjusting it) and made it put too much pressure through each shot?

I also noticed that my trigger is “loose” (warbles left, rite, back and forth) before it engages the final trigger click. It does not seem to have a 2 stage or any spring to keep the trigger from having this free play. Could this be the issue for such high pressure usage per shot?

any advice would be great guys

 

[DesertSilver]

I think the precharge piston is stuck near the end of the pressure tube. There's supposed to be 1800 psi precharge which allows you to have pressure with a small amount of pumping but not 3600 psi. Is your rifle still under warranty? If it is send it back for repair. If it was my rifle, I'd release the precharge pressure then pump it up to 3600 psi which should break the piston loose. Then release all of the pressure and pressurize the the precharge to 1800 psi and call it good. But, you have to have the special probe to fill the precharge chamber. That's why I said if under warranty send it back. Some might suggest just releasing the precharge pressure and just deal with the increased amount of initial pumping and don't worry about the precharge pressure. The main thing is the piston needs to be broke loose so you have the whole pressure tube volume of 50cc to shoot from. Hope this helps and didn't confuse the situation more for you.

 

[cegd]

Thanks for the great info and advice. Butch has also been a great help and suggested the pre-charge could be a little high. Unfortunately it’s out of warrantee. Is there any way to get hold of the “special” fill probe if I want to go with releasing the pre-charge and trying to loosen up the piston? 


Is there any other place I could put Sillicone oil other than the lube hole below the pump leaver to try and get lubrications to the piston?

Thanks again guys for all your support! This forum is awesome! 

 

[DesertSilver]

What pressure do you shoot at? Whether I have the precharge or not I always try to have my pressure between 2800 and 3000 psi. At those pressures the precharge IMHO would have no effect but I pump 5-6 pumps after each shot. The special probe I have was made by soupyy on GTA. Have no idea where else to get the correct probe at. 

 

[cegd]

So to update on my Seneca Aspen pump issues, I kept using the gun yesterday and added more oil as suggested to see if i could get the precharge piston to loosen up and slide free before following the steps of elimination shared by SilentSquirrel in another thread. So I decided to fill the gun past 3600 to near 4000psi (I knew the burst disk is rated for 4500), and suddenly I heard a popping/springing sound come from near the pump. I noticed the pressure pressure gauge dropped to about 2000psi. So I began to pump it up again and instantly there was no where near as much resistance on the extension stroke, and it now takes about 70-75 strokes to pump the gun up to 3600 From 0. Now it shoots the 14-16 shots on low power like a boss!


i can’t say for sure what it was that caused my issue, but I believe as suggested by other members, it was the precharged piston being “stuck”. The lining and slight “over pressure” forced it to move and then slide free.

thanks to everyone here for all their advice and input.

 

[cegd]

Anyone here know the thread size on the gauge? Butch confirmed it’s an 8mm. Can anyone confirm M8 x 1?

 

[DesertSilver]

So to update on my Seneca Aspen pump issues, I kept using the gun yesterday and added more oil as suggested to see if i could get the precharge piston to loosen up and slide free before following the steps of elimination shared by SilentSquirrel in another thread. So I decided to fill the gun past 3600 to near 4000psi (I knew the burst disk is rated for 4500), and suddenly I heard a popping/springing sound come from near the pump. I noticed the pressure pressure gauge dropped to about 2000psi. So I began to pump it up again and instantly there was no where near as much resistance on the extension stroke, and it now takes about 70-75 strokes to pump the gun up to 3600 From 0. Now it shoots the 14-16 shots on low power like a boss!


i can’t say for sure what it was that caused my issue, but I believe as suggested by other members, it was the precharged piston being “stuck”. The lining and slight “over pressure” forced it to move and then slide free.

thanks to everyone here for all their advice and input.

I would've suggested that but figured I'd get crusified for suggesting it. It's good you got it fixed

 

[cegd]

I am afraid to report that after some more shooting, the power plant is behaving strangely again. It is once again only taking 10-15 pumps to fill to 3600 from 0 and I am getting resistance on the outward extending stroke. I can’t understand why this issue is intermittent. Could there be a blockage somewhere or perhaps lubrications is not getting to the part which occasionally gets stuck.

Desert Silver, you mentioned you got the special fill adapter for the front end service valve on the rifle from “souppy on GTA”. Sorry but I’m not sure who or where that is. I would really like to get one Incase I need to repair the pre-charge piston.

 

[Butch]

The blockage is from the high pressure seal failing causing the suction on the up stroke. 
Butch

 

[cegd]

Thanks again Butch for your input How would you Go about fixing that? Is this a pressure seal for the pump? Where is the high pressure seal located?

 

[Butch]

The high pressure piston seal is the small piston on the inner rod. You will have to disassemble the pump to get to it and it is not a hard job to do. Should be plenty of info in the post for you to do the job. 
Butch

 

[DesertSilver]

I am afraid to report that after some more shooting, the power plant is behaving strangely again. It is once again only taking 10-15 pumps to fill to 3600 from 0 and I am getting resistance on the outward extending stroke. I can’t understand why this issue is intermittent. Could there be a blockage somewhere or perhaps lubrications is not getting to the part which occasionally gets stuck.

Desert Silver, you mentioned you got the special fill adapter for the front end service valve on the rifle from “souppy on GTA”. Sorry but I’m not sure who or where that is. I would really like to get one Incase I need to repair the pre-charge piston.

I'm not sure souppy is still making them. That was about 2 years ago. The bottom one is for the precharge chamber.

 

[cegd]

Do you have a contact for souppy? How did you initially contact for getting the probe?

 

[cegd]

I managed to open up the pump today to check the condition of the “small piston“ o-ring. As highlighted by others, it was impossible to remove the “Rear moveable sleeve” (bottom black plate with 4 holes) even using a proper pin wrench and vice grip on the steel tube! The grip keeps slipping on the stainless steel tube (tried leather piece, rubber etc) despite gripping the correct flat groove on the tube!
Unintentionally, with a lot of turning of the entire pump cylinder, the brass “small tube connecting sleeve“ unscrewed it’s self inside (Prob friction) and allowed me to slide out the clear tube, stainless steel tube and small piston all at once.
I’ll have to take the stainless steel tube to a machine shop or workshop to see if they have better tools or a way to unscrew it from the “rear removable sleeve” before I can reassemble the rifle.

 

[cegd]

I have another question, since I’m “rebuilding” the pump, I noticed that there is not “Desiccant” in the clear tube of my rifle as shown in the parts list / assembly guide. Do you guys have it in yours? Is it effective? Should I bother adding it?

I’m also trying to understand if the oring of the small piston is suppose to be snug/tight around the brass rod or should it be slightly loose with some play? I ask because I notice that the diameter of the rod is 2.68mm but the #006 o’rings have an ID of 2.9mm.

Have any of you tried Viton o-rings instead of the standard NBR? If so which o-rings did you swap out? How are the results?

 

[DesertSilver]

Do you have a contact for souppy? How did you initially contact for getting the probe?

https://www.gatewaytoairguns.org/GTA/index.php?action=profile;u=11366

 

[Butch]

Viton orings work better than the NBR orings. The size you need is 006. Get a few of the 70-75 duro and a few of the 90 duro. Try the duro 90 first but be careful pushing the piston back into the tube because you can bend and break the end very easily. If it doesn’t want to go in try the duro 70s as they are softer and easier to get the piston back in. Use silicone oil or silicone grease on the piston during assembly. 
Butch