Leaking BSA Ultra Valve Advice & Suggestions

[wildy]

Hi All,

At my wits end with my old Ultra. Its an early .117 MMC single shot that is leaking past the knock open firing valve. I have re-sealed the whole gun while its been apart and put in a brand new knock open valve and stem seal but it continues to leak when filled.

It has an after market Huma reg fitted.

When the old valve was removed the face was slightly rounded but the new is a square edge. I am not sure if the slight bevel was due to wear? Looking inside the valve body the mating surface when the valve seats looks conical. Should the replacement valve be beveled slightly?

Its been cleaned out many, many times and there doesn't seem to be an dirt etc stopping a seal.

I have pretty much run out of ideas..Anyone able to offer any help or advice?....I'm stumped!!

Cheers

[DM80]

The valve from new are faced off flat the edges do round with use etc the reason why it could still be leaking past the valve is if the regulator pressure is set to low or needs a service if its low sometimes the exhaust valve wont seat correctly.

Dave.

[wildy]

The valve from new are faced off flat the edges do round with use etc the reason why it could still be leaking past the valve is if the regulator pressure is set to low or needs a service if its low sometimes the exhaust valve wont seat correctly.

Dave.

Thanks for the input Dave,

That crossed my mind so I tried higher reg pressure and also removing the reg...still blumin leaking!

The mating surface in the valve body doesn't look fantastically smooth, I'm wondering if its possible to have it honed smooth and flat?

PCP's can be very frustrating, particularly as my BSA R10 is also leaking from the reg! (waiting for seals for that).

Old BSA Spitfire keeping my going plus the faithful springers.

[jirushi]

I have had a slow leak in a S10 I was servicing.
A friend who had this with his R10's (s!) advised me to polish the brass valve seat.
I found this very scary to do but it seems to have worked.
Using a dremel with polishing bit, cut with scissors to fit in the valve seat.
And Autosol.
I also followed his advice to put the valve stem in a drill and smoothen the valve surface with 2500 grit wet&dry.
Now this was scarier. Not sure if this was good advice, but the S10 is now holding air.
However I did the same thing with two Spitfire's I'm resealing.
Both still had their infamous slow leaks after a full reseal.
I thought it could be the rear of front valve.
Gave both the same polishing and valve smoothening treatment, leading to a violent leak from the front valve.
I feel like a total idiot for having done this.
I guess the valve "smoothening" didn't go well - not completely straight. Will have to send them to someone with a lathe, hopefully that will be curative.
But obviously I wouldn't touch your new valve.
I would try the valve seat polishing though.
You will only be removing a tiny tiny bit of brass, and eliminate any small scratches that can cause air to escape past the valve.
Don't push on the Dremel, as the metal pin can then stick out of the polishing bit... Been there done that.

[wildy]

Thanks Mate
I may give that a go as the new valve face looks spot on under magnification.
If that fails then its off to a specialist when the lockdown is lifted as its emptying my bottle at an alarming rate.
Cheers

[jirushi]

Thanks Mate
I may give that a go as the new valve face looks spot on under magnification.
If that fails then its off to a specialist when the lockdown is lifted as its emptying my bottle at an alarming rate.
Cheers

You're welcome.
Any luck yet?
I would be interested to know if the polishing works.
Many thanks

[wildy]

You're welcome.
Any luck yet?
I would be interested to know if the polishing works.
Many thanks

I haven’t plucked up the courage to try it yet, I’m waiting on the delivery of one more new valve stem to try. If that doesn’t work then out comes the dremel. I’m not sure which polishing but to put in it though. Ive got some paper polishing bits but I’m worried they may be too aggressive. Also some floppy cloth type that I think could buff it smooth with the jewellers paste I have. I’m hoping the new valve works!

[wildy]

Quick update.

On the Ultra the 2nd new valve stem sorted it. I had it serviced a number of years ago (is a very early one) and I measured the valve I removed the first time which was the later one so I ordered that type and installed one of the same. I have now put in the early type which is a little wider and sealed spot on without any polishing to my relief!

The R10 Mk1 was leaking through the reg. New seals throughout and bobs your uncle back to being a tack driver. I was a little confused that the new regulator seals looked a little different to the old ones but I think that was due to the old seals being in for so long that they had gone hard. The middle inner seal almost looked like a flat washer rather than an "O" ring but the new seals worked a treat.

Now my only problem is getting my scuba tank filled as its down to 200bar. Tried topping the R10 up with a pump...sod that for a lark...got about 10 pumps in before I could not get any more in and I'm a heafty bloke...nearly killed me! The Ultra should be OK with the pump though. Just my luck two guns sorted and running out of air.

[the bish]

Tried topping the R10 up with a pump...sod that for a lark...got about 10 pumps in before I could not get any more in and I'm a heafty bloke...nearly killed me! The Ultra should be OK with the pump though. Just my luck two guns sorted and running out of air.

Isn’t there a restrictor screw in the BSA Fill Probe that has to be loosened or removed if you’re filling the gun with a hand pump?

Edit.

Have a look at the filling instructions.
http://www.bondbywater.co.uk/doc_upl...0Multishot.pdf

[jirushi]

Quick update.

On the Ultra the 2nd new valve stem sorted it. I had it serviced a number of years ago (is a very early one) and I measured the valve I removed the first time which was the later one so I ordered that type and installed one of the same. I have now put in the early type which is a little wider and sealed spot on without any polishing to my relief!

The R10 Mk1 was leaking through the reg. New seals throughout and bobs your uncle back to being a tack driver. I was a little confused that the new regulator seals looked a little different to the old ones but I think that was due to the old seals being in for so long that they had gone hard. The middle inner seal almost looked like a flat washer rather than an "O" ring but the new seals worked a treat.

Now my only problem is getting my scuba tank filled as its down to 200bar. Tried topping the R10 up with a pump...sod that for a lark...got about 10 pumps in before I could not get any more in and I'm a heafty bloke...nearly killed me! The Ultra should be OK with the pump though. Just my luck two guns sorted and running out of air.

Nice! Congratulations, good result. Ah yes I remember that now, two sizes of valve heads. All quite confusing. So with the older Ultra's with hammer tube, valve tube and cylinder and thus a steel valve housing instead of the later all brass valve housing, has the wider valve head. I'll make a note of that.
R10 resealed. Now some air and many pleasurable hours ahead of you.
Good point above about the restrictor screw, rings a bell. But in any case do you put your weight on the pump whilst going down? I only weigh 74 kg, I am not strong but I do all my pcp charging with a 15 year old Hill's pump. Buddy bottles I do in 2 episodes. From about 80 to 150 bars, a break, then to 230. Nice to not have to worry about getting a tank filled, imo. My chest is hovering above the pump whilst going down. I kind of "fall" onto the pump handle. Not much force required.