BCM Community
Bus Discussion => Bus Topics ( click here for quick start! ) => Topic started by: 64MCI on June 29, 2026, 05:59:15 AM
Hello again!
I got home from a trip yesterday and before moving my bus to it's normal parking spot, I got an air leak that won't allow the bus to build air pressure.
This is the view in front of the rear axle on my MC5. First question, is the blue assembly/part the inversion valve?
20260628_164318 - Copy.jpg
Here is the spot that is leaking all my air.
20260628_164401 - Copy.jpg
Assuming it is the inversion valve, I've read some folks rebuild them and some replace the whole thing. What say you?
Thanks!
I'm still not sure what the valve above is, but I did find this thread:
https://www.busconversions.com/forum/index.php?msg=171109
which indicates that even though the valve is leaking, it might be from a DD3 diaphram or something else. Seems like I need to do some more digging.
That is your relay valve.
There are folks on this board who can tell you exactly what lines to pull and cap to diagnose the source of the leak. Or you can spend some quality time with your air line schematic and figure out the air flow and diagnose it that way.