Help tracking down a gas leak

[DVCNick]

So I'm on my first keg after making some modifications to my kegerator setup:

-Moved bottle outside
-Inside, added a three way splitter manifold with a shutoff valve on each output.

The problem is, I have a slow leak in one or more places. I've turned the pressure up and sprayed every connector I can find with Star san, looking for bubbles, and none to be seen by me so far.

The beer has been carbing for a week, so I don't think it is taking up much CO2 right now, and also my pressure will eventually drop to zero (only let it go that far once). Here is what I'm doing right now:

Gas up the system to, say, 20 PSI. Then turn the gas off. Fifteen or twenty minutes later it is at 15 PSI, and will drop to zero if given enough time.

Second test: Gas up the system to 20PSI. Turn off both the gas, and the shutoff valve at the manifold (trying to isolate the leak up or downstream of the manifold valve). Given enough time, the pressure will drop to zero. Definitely got a leak upstream of that valve.

BUT, then I open that valve an expect to hear some kind of movement and non-zero reading on the regulator... nothing. Seems like there is no pressure downstream either. Downstream is really just the keg and ball lock gas-in. This keg as far as I know has always held pressure in the past.

Am I going to have to disassemble this entire thing and pressure test it submerged in a tub? I think the leak is very slow. I had it pressured up all weekend for three days while I was out of town, presumably leaking the whole time, and the bottle still has plenty of gas in it.
Thanks for any pro tips.

 

[LittleRiver]

...Am I going to have to disassemble this entire thing and pressure test it submerged in a tub?....

I once did that very thing and found a leak in one of my connections.

But before you do that check to make sure it's not the connection between the C02 bottle and the regulator. That is a very common spot for a leak.

 

[EnglishAndy]

The regulators that I've seen will vent through the body if you turn them back beyond zero to where the knob feels loose. This can be a very short distance, worth checking that. It could also be leaking through the regulator body when it shouldn't. I had one that did that.

 

[IslandLizard]

Those little shutoff valves on the manifold perhaps? I had one that leaked when touching the (red) handle.
Also, only keep them in 90° positions, they may leak in between.

Check the whole manifold too, there is very little tape on the shutoffs, and only 2 turns of thread in the aluminum body.

Do you have a "fisheye" flare washer between all metal to metal flare surfaces?
None are needed on the plastic MFL QDs, their plastic tippy is the "seal."
Make sure all connections are tight.

 

[DVCNick]

I torque all the hose clamps pretty tight. Unfortunately all my hose barbs are not the same size, so I have a couple of double sided hose barbs to step changes in hose diameter before the manifold. So I have four unnecessary couplings there. If I can find the right barb size piece to thread on to the regulator I could eliminate that and just have 3/16th going all the way from the regulator to the manifold.

I think you guys are right... the manifold is probably the most likely culprit. there are five threaded connections and three valves, any of which could potentially be leaking. I had to switch the input barb to the other side when I got it, so I think the input barb and bolt on the other side are likely good (I did them with fresh tape of course. The three outputs, I can't even see any tape on them at all. Probably should take them off and re-tighten with fresh tape? The other two currently unused valves are turned at 90 degrees and should be closed.

I still don't get why the keg side pressure would seemingly drop to zero with the valve closed though. That would mean that either the keg is leaking (I don't think it has before) or the manifold valve is leaking, AND there is another leak upstream as well.

Not sure about fisheye washers, but this regulator and keg have been used directly together in the past with no issues, so I have to think the issue resides somewhere in all the new connections.

 

[homebrewfinds]

I would take a hard look at the gas post o-ring. That's a pesky spot to check for leaks since it's only in play when a QD is connected and, it's difficult or impossible to check for a leak when the QD is on. A couple resources... check out my post on the pressure gauge method of checking for co2 leaks and here is my post on bulk oring sources and part numbers. I would grab extras, so you can replace as needed.

 

[balrog]

The levers on those valves are notorious, as per @IslandLizard .
The submerge in tub method is awesome, but for the whole get it apart and into the tub bit.

 

[DVCNick]

So I kegged another one yesterday, and since the leak is kind of slow, figured I would just hook it up to the second port on the distributor and let it roll.

Now the leak seems slower, and the new keg is not carbed so it should be taking up C02, so I'm not even sure it is leaking right now. Maybe the leak was at the second valve on the distributor that I just hooked up to the new keg. If that is the case it kind of sucks since I won't always have a keg hooked up to it, and it would have to be leaking through the valve and the loose ball lock gas in fitting.