Sometimes air leaks can be deceptive. Air works in a circuit much like electricity. Where air leaks present themselves is not always the cause of the leak. We have prepared some simple tests to help. Eliminate wasting valuable time and the frustration of changing a valve and still having the same problem.
The majority of the time a leaking service relay valve is not the bad valve at all, rather a bad spring brake chamber or QR1C quick release valve.
How to determine if an air leak from the relay valve is the valve or a spring brake chamber.
- Step 1 - Block your wheels and release your parking brakes.
- Step 2 - Trace your delivery line to the service port of the spring brake chamber.
- Step 3 - Disconnect the line from the service port of the spring brake chamber, check to see if air is leaking from the chamber itself, if so the chamber is bad and needs to be replaced. The same test should be repeated on all spring brake chambers. It is not uncommon to have more than one bad chamber.
- Step 4 - If you have performed this test on all chambers and you still have air coming out of the delivery lines from the valve you have a bad valve. The valve will have to be identified and replaced.
If your system uses a QR1C valve on the spring brakes it can be defective and will lead you to believe your relay valve is bad as well.
How to test your QR1C valve.
If this valve is used in the spring brake circuit the balance port on this valve will be plumbed into a delivery line from the relay valve to the service port of your spring brake chambers.
- Step 1 - Locate the QR1C valve and remove the balance port line. If the air is coming out of the valve the valve is bad. If the air is coming out of the line and you have not performed the spring brake test described above do this now.
- Step 2 - If you have determined all spring brake chambers are good the valve is bad and will need to be replaced.
TECH TIPS FOR TROUBLE SHOOTING RELAY, SPRING BRAKES, AND QR-1C VALVES