mac valve for my step well ram leaks out the exhaust port.

[twslp]

HI can anyone chime in. I have replaced my mac valve that controls my step well slide twice. leaks out the exhaust port when off. ? thanks. 99 marathon.

[drivfour]

Mine did same thing,even new one. Valve needs a bit over 20 psi to move to close

[Joe Camper]

Its the internal oring on the bottom of the ram on the cylinder itself thats bad and the leaking air is coming out the exhaust on the Mac valve.

[twslp]

thanks joe. i can buy that one. but if the mac is not powered seems it should not pass air thru. am i thinking wrong. or is the air stored in the ram thats leaking ? its leaking when no power to the valve .and step slide not in use. i have a new norgren reg set at 19 lbs and it leaking at the exhaust.

[PrevostNewbie]

This is what Joe is talking about. If air supply to retract the step slide is passing by the piston seal, it will show itself by escaping out the exhaust port. Same thing can be said for the other direction. Follow the Red arrows.

[PrevostNewbie]

Here is a very simple illustration of how a valve and cylinder work.
https://www.youtube.com/watch?v=iIMgJ-wa0Y8

[Gil_J]

Mike, great picture to illustrate how most pneumatic rams and valve controls work.