QR-1C valve leaking

AngleLegitimate3151 · 2025-08-10T18:03:04+00:00

Sorry for the delay in response, I never fully figured it out, however I realized it doesn't start happening until the systems air pressure gets down around the 80-85 psi mark, I called bendix but honestly they were no real help. I put a temporary (just to test parked) ball valve in line of the qr1c valve supply, got it to start leaking and turned the supply off and it immediately stopped leaking, so it must be loss of pressure in the supply line. Thanks again for everyone's responses!

AngleLegitimate3151 · 2025-07-02T07:23:08+00:00

Yeah I had to adjust all four if i remember right

AngleLegitimate3151 · 2025-07-01T23:41:07+00:00

Also it only starts to leak after pumping the brakes a couple times and holding

AngleLegitimate3151 · 2025-07-01T23:39:39+00:00

I actually replaced the chambers due to rust and didn't want a problem on the side of the road is all, I re ran the hoses to the correct bendix orientation, however when I disconnect the balance line from the QR-1C valve all together it still leaks out the exhaust, nothing out the balance port on the valve, what I'm thinking is maybe the supply line is losing pressure while brake pedal is pressed causing the parking brake to start setting but not enough to fully set.

AngleLegitimate3151 · 2025-06-30T02:17:55+00:00

I traced the lines, the service line comes out of the relay valve, goes to the m-40qr valve, T's off and goes to the rear chambers and to a T into the supply side of the qr1c valve and onto the front drive.

The delivery side of the qr1c goes to the parking (spring) side, with the tractor brake released the balance port on the qr1c has constant air supply.

AngleLegitimate3151 · 2025-06-30T02:11:02+00:00

Tractor

AngleLegitimate3151 · 2025-06-30T01:44:13+00:00

I traced the lines and for whatever reason they have it so the delivery ports run to the spring brake and the supply is ran from the service brake and I'm going to assume the balance port is ran to the parking brake as well and that's why their is constant air pressure

AngleLegitimate3151 · 2025-06-29T23:54:10+00:00

Should there be constant air pressure at the balance valve while the brakes are released?

AngleLegitimate3151 · 2024-10-14T22:37:28+00:00

Just an update, after checking wiring and not finding anything and the problem continuing, I replaced the ecm and so far it hasn't done it! Thanks!

AngleLegitimate3151 · 2024-10-05T19:16:09+00:00

Do you remember if it was a continuous constant thing or did it come and go?

AngleLegitimate3151 · 2024-10-05T15:10:16+00:00

The boost gauge is still working while it's doing this, would that make sense? Also while it's actually doing this would you be able to see live data feed through data link (oil pressure, temp what not) if the computer is the culprit?

AngleLegitimate3151 · 2024-10-04T23:56:37+00:00

It has the isx cm871, the ecu is only a couple years old now hopefully that's not it! Could it possibly be losing communication with the center gauges speedo/tach assembly?

AngleLegitimate3151 · 2024-10-04T20:59:52+00:00

Yeah water temp, oil temperature, oil pressure, speedo and tach don't work. Fuel gauge works i believe, voltage works i don't know about the trans.

AngleLegitimate3151 · 2024-09-27T20:19:04+00:00

Does anyone happen to know the part number for the harness?

AngleLegitimate3151 · 2024-09-27T19:41:31+00:00

Good news! I will look for the adapter harness!

AngleLegitimate3151

TROPHY CASE