Daystate Valve seating/leak repair assistance

[TWebster]

I have an old Daystate Mirage XLR I picked up from the classifieds not too long ago. Great shooting, lightweight rifle! Unfortunately, the valve started leaking the other day, and I haven't been able to sort it out.

I narrowed it down to it leaking past the valve where it seats in the valve body. There are no obvious/visible defects or damage to either the valve stem or valve body/seat. All feels smooth to the touch and it seems to drop in just as it should, and there is good tension from the internal spring.

I have cleaned the surface of the valve seat and the valve stem a bit, and tried setting the valve stem in different positions, turning a little each time to see if there might be an obvious uneven/unlevel spot, but no luck.

Since this gun is almost 25 years old and Daystate didn't make a ton of them, there are no spare valve parts to be found at the usual places. And, I'm hesitant to try anything too aggressive!

Any thoughts or ideas/suggestions appreciated!

 

[JimD]

I do not know if it has worked yet but I have a gun that leaks at the valve and I used some valve grinding compound on the valve today and plan to put the gun back together tomorrow to see if it worked. I put the valve in a drill, put a little grinding compound on the seating surface and spun it against the seat. It looks a lot better but the proof will be in whether it leaks. This valve is brass on what I think is a stainless steel seat from my P35X. If it works, I will try it on a hard plastic valve in my P35 that I reduced in diameter.

I got the valve grinding compound from an O'Reily autoparts store for $6. Cheap fix if it works.

Your situation would seem to be much more minor. I would probably try a little JB bore cleaner as an abrassive and spin the valve in the seat the same way. The valve grinding compound does not seem to be very agressive, however.

 

[KatoKevin454]

I use Silicone oil on a rag and spin the poppet in a drill and apply pressure to the sealing surface with the oily rag, allowing it to get very warm, I also use Scotchbrite pad on the metal part

 

[SilentSquirrel]

Hopefully @nervoustrig will chime in
For a first pass on my FX Indy leaky valve he advised me not to lap the valve with the seat.
But rather to polish the seat with a very, very mild abrasive.
Nothing more course than toothpaste

I looked for the post but could not find it
Sorry!

Edward

 

[nervoustrig]

Use a black Sharpie to color the contact faces of both the poppet and the valve. Apply a light abrasive* and spin them together for long enough to clear the ink from the surfaces. Wipe away the abrasive and inspect both with the aid of magnification. If there is a low spot such as a fine radial scratch, the ink will remain behind to signal what needs to be remedied.

Then based on the severity of the defect, you can consider how to proceed. For example, whether to stay with a light abrasive or step up to something more aggressive, whether to continue lapping both together or instead start by dressing the flawed part alone before doing a final lapping pass, etc.

* light abrasive - some examples include J-B Bore Compound, medium metal polish, valve compound in the realm of 400 / 600 grit, homemade slurry of oil and diatomaceous earth powder

For additional reading, here is a related thread:

Tuning - Peek poppet lapping for seal

What are you using to lap in your peek poppet to seal I have used some metal polish that had worked a couple times but this time I can't seem to get the poppet to seal all the way up I also tried a 30 degree and 35 degree taper just won't seal at 150 bar I now peek will seal all way down to like...

www.airgunnation.com

 

[Booder98]

A little off topic but good to know - valve grinding compound also works to help loosen stripped screws. A little dab on the tip of the screwdriver does the trick.

 

[JimD]

Well my use of valve grinding compound on the valve and seat of my P35X seems to be working. I filled it to 150 bar half an hour ago and it is holding. I only assembled the air tube (in case I had to try again) so now I need to put it back together and see how well it is working now. This gun was gifted to me because the previous owner could not get it to shoot at a higher velocity than a bullshark. It is a 25 caliber that had a 22 caliber sized barrel port and smaller passage through the block and valve, like a 22 caliber. That is all opened up now so I'm hoping power will increase significantly. It has a 40mm longer barrel and a 60cc plenum so it should, logically, be more powerful.

I used Permatex valve grinding compound that starts out pretty coarse, 120 grit if I remember right, but breaks down as you use it to much finer grit. I finished with JB's. I have no previous experience so I don't know if what I did was best but so far it is successful.