- 518
- 179
- 43
- Location
- Stoneville, NC
If the top diaphragm in the tractor protection valve is bad, it will leak air out of the vent cap on the side of the valve when you are pressing the brake pedal. I'm not sure what other leaks you would have if other parts of the valve are bad. There is a rebuild kit for the valve available at Napa. http://www.steelsoldiers.com/showthread.php?140345-Air-Brake-Info-and-Troubleshooting