Losing Co2

[Bubba Brew]

My keg is drawing perfectly and I doused everything with soapy water. I see no leaks but my Co2 bottle keeps going empty. I started with a fresh 3 lb bottle 1 1/2 weeks ago on a half keg of Busch light. Never checked gauges but 1 week into the keg the beer tasted flat. Opened the fridge and found all pressure gone from keg and tank. I had another tank so I swapped it out with the empty one which recharged the beer and all was good again. Now I see that tank is near empty as well. I refilled the the original tank again but I can't keep going through tanks of gas!
Before starting this keg I charged the gauges with gas and left it sitting a few days. It held pressure fine.
Does anyone think it could be the coupler? Or the gauges? I've had this equipment for 20+ years with no problems but somewhere it must be leaking and I can't see it. Usually a 3 lb tank lasts for multiple 1/2 kegs. Two different bottles have drained empty on me. I keep them inside the fridge with the keg. It's so expensive having the keg I don't know what to replace or if it's worth it.
If I need to replace the gauges, I would only NEED to have the pressure gauge and not both pressure and capacity gauge, right?
Thanks for any suggestions..

[djc]

Run the pressure up to 50 and listen for the leak, and redo the soapy water test if needed. If all the washers are 20 years old you should treat yourself to new ones.

[Bubba Brew]

Thanks djc. I will try the pressure raise and soap. I do have all new washers in place but maybe the pressure test will reveal the problem.

[PointPleasantNJBeerguy]

Just to add to DJC's 50Lb test. Don't leave hooked up to keg for very long if cranking pressure up to 50lb. If you crank to 50lb and leave tapped you will over carb the beer. Short period of time just testing will be ok.Just bleed excess back out by pulling ring on coupler to blow off excess co2 out of keg.
But I would do untapped and coupler handle left up(or if you have wing handle coupler, handle twisted up)
I'm betting your co2 regulator to tank gasket is flattened out from years of use.I would double up with a fiber washer if that is the case.After twenty years hoses get hard. So could be where hose is co2 hose is clamped. Or last your rubber check valve in coupler is no longer sealing to hose barb.

[Bubba Brew]

NJBeerguy. Since I also have all new hoses and the regulator did hold pressure for 3 days when I tested, I'm thinking you may be onto something with the check valve. It is original. I ordered a new coupler but I'm gonna take a look at that check valve (and double any suspicious washer.

[PointPleasantNJBeerguy]

You can usually fix a leak on co2 check valve with a #759 neoprene beer washer.

[Bubba Brew]

Are they a thin washer? I have a couple I got when I refilled the Co2 tank, (if that's what they are)..

[PointPleasantNJBeerguy]

Item Link.

No fatter and softer than a co2 washer. Its the washer you have on end of beer line inside nut that threads to coupler.

[Bubba Brew]

Gottcha..Thanks again..