I'm trying to follow advice of other posters on testing my hoses by using a grease gun, water, and pressure gauge, but have found that there is really nothing to hold the pressure from bleeding back in to the grease gun. Does anyone know of a simple one-way valve that could be used for this? Any other ideas to make it work? I realize I could have a hydraulic shop do it, but it would be mucho convenient to be able to get it done right here, right now.