Parking Brake Issue

I'm going to guess it's time to PM the air system. It's a long shot, but it could be full of moisture. When air and condensation travel through your parking brake, the moisture doesn't move as fast as good dry air.

You can drain the tanks with the hand valves to see if they're full of moisture. If they are, time for a dessicant cartridge and some maintenance. If not, it could be time for a new brake valve.

 

i have same issue with my volvo, as dave26027 said, i do have water in air tanks problem.

 

it sounds as if you need to bleed off water out of air tanks, the tanks have probally started to corrode and start to bleed out of the exhaust relief valve. you could also having a exhaust release valve thats going bad or clogged. try draining the air tanks while the truck is running and do it for about 5 minutes so the air compressor kicks in and keeps the pressure up.

 

where is this valve ( exhaust release) located on volvo 670. This problem only happens with the trailer hooked. Never with bob tail, are there two different valves on truck one for truck and other for trailer.

 

The truck brakes could also be out of adjustment. As previously stated, PM the system.

 

Have seen on 05 volvo this to be normal on shutdown.
Actually part of the system draining the air when shutting the truck down. Not necessarly when setting the brakes.

 

Did you ever find out what valve was causing this? I have a 2007 Volvo 780 that takes 10-20 seconds to set the parking brakes when it has a trailer attached to it...

 

Bad valve needs replaced. Get it to the shop ASAP