I have an 08' Volvo VHD ten wheeler and it has three air valves right behind the cab. One air valve is mounted above the other two, the one that is mounted above the two is constantly leaking air. If I step on the brake pedal it stops, but if you hold your foot on the pedal it slowly starts to leak again. I have no idea what the valves do and will probably end up bringing it to a local mechanic to get it repaired. My question is, is the valve just failing or is something else in the air system failing causing the valve to bypass? Here is a pic of the valves.
Looks to be the relay valve. They will get trash in them and leak constantly as they're plumbed into constant air pressure. If you can get some numbers off of it a local truck parts place will have one. They're easy to change, just take pics and match where the lines go when you replace it. Doesn't have to come from a dealer and shouldn't be very expensive. For sure under a $100. Worst case pull it off after making sure you know what line goes where and have the parts place match it. Nothin else generally causes the leak they just get trash in them or the diaphragm breaks down and leaks. Simple fix. Junkyard
Thanks for helping out, I'm gonna try to get a number off of it and go from there. Really appreciate it!
Thanks again Junkyard! It was a bad valve, replaced and back on the road again!
Sweet. I love it when a plan comes together. (Said with a cigar in my mouth......).