I have a twin engine gaffrig air muffler setup. When i close the mufflers, after about a minute or two, the port side tips open, while the starboard side will remain closed. Sucks having to keep hitting the switch, as i would like to keep them closed while rafted up to keep any possible backwash from the tails.

Is it just a matter of checking the air lines for leaks, or could the little cylinders on the mufflers be bad.

I have the same problem and can't get it worked out either. I took the cylinders apart and cleaned and greases them and it helped some, but they still creep open slowly

You can also take some dish soap and water, squirt it on all the connections, see the little bubble and there is a little leak, see big bubbles and there is a big leak. Same thing the tire guy's do to find a leak in a tire. Clean with some carb cleaner.

Like Vector said, you have a leak. That is the only thing that will make them open on their own. When you close them, they are supposed to stay pressurized with air. When the air leaks out, they open. They are spring loaded, so just a little tiny air leak will make them open. You need to find the leak.
Eddie

On the Merc silent choice air system, the pressure releif valve gets dirty over time and a simple remove and clean usually fixes that. I'd assume the Gaffrig is about the same setup?? Something to check. Also checked by the soap method. Mine were held open when pressurized and would close under the spring return closed position when the pressure leaked down. Yours appearantly is opposite it appears.

Odd why only 1 motors tips open though. Once the pressure leaks down enough, all 4 should open. Unless you have 2 pumps.

Got the soapy water spray bottle out. Found that when pressurized, the little valve mounted to the pump body was leaking a bit. So I removed the air line, sprayed some wd40 in there, let it sit. Reconnected it, and bingo! Mufflers stayed closed for at least an hour while i was there tinkering. A lot better than the minute they were staying closed before! Im happy now.

That's the relief valve. Just a rubber disc (if I recall correctly) held closed under spring pressure. If you hold the pump switch on, that valve opens up bleeding off the excess pressure. The rubber gets dirty over time and doesn't seal.

Stopped back at the garage today. They were still closed!!!!! 24 hours. I'd say I got a good seal now. Opened them up to make sure they werent stuck!

you da man!

The Merc silent choice system defaults to thru prop. You cant open them when it breaks.