Tweet
Some VU4s will leak back to the tank if the tank's at a lower pressure than the bags. Often this will be just one corner if the pressure differential is minimal - it's corner 3 on mine, but apparently it can vary. Anyway, if your bag pressure and tank pressure are close, a 9 psi drop at the tank could cause a corner to leak down.
What'd I'd be tempted to do to help isolate the leak is to get a check valve and put two PTC fittings on it, then stick that between the tank and the valve manifold. If the corner still leaks down, you've got a leak after the check valve. If the tank still leaks down but the corner doesn't, you know you've got a leak before the check valve.
The first place I'd look if you've got a leak before the tank is the leader hoses on your compressors. Viair leader hoses are... cheesy, IMO. Mine started leaking less than a year into ownership, and it's not the first Viair compressor I've had with a leaking leader hose. In my case, the leak was so slow that I couldn't detect it with a soapy spray. Eventually I replaced it with an SMC check valve and some DOT air line (though one ought to be VERY careful not to overtighten the fittings at the head - I learned the hard way, and $35 + shipping for a new 444C head bears testament to that).
What'd I'd be tempted to do to help isolate the leak is to get a check valve and put two PTC fittings on it, then stick that between the tank and the valve manifold. If the corner still leaks down, you've got a leak after the check valve. If the tank still leaks down but the corner doesn't, you know you've got a leak before the check valve.
The first place I'd look if you've got a leak before the tank is the leader hoses on your compressors. Viair leader hoses are... cheesy, IMO. Mine started leaking less than a year into ownership, and it's not the first Viair compressor I've had with a leaking leader hose. In my case, the leak was so slow that I couldn't detect it with a soapy spray. Eventually I replaced it with an SMC check valve and some DOT air line (though one ought to be VERY careful not to overtighten the fittings at the head - I learned the hard way, and $35 + shipping for a new 444C head bears testament to that).
Comment