Aceptable non running air leak down on a 2007 freightliner Columbia

Discussion in 'Trucks [ Eighteen Wheelers ]' started by Hulld, Apr 30, 2016.

  1. Hulld

    Hulld Road Train Member

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    Just wondering what the acceptable non running over night air leak down on a 2007 freightliner Columbia ?
    I have no leak down problem when running down the road at all but if I let it sit over night not running I have 0 air pressure in the morning.
    Is this normal?
     
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  3. ExOTR

    ExOTR Windshield Chipper Extraordinaire

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    I'm driving one older than yours, and only lose about 25psi overnight.(manual tank drain though) Break out the soapy spray bottle, and spray down every connection and valve you can see.
     
  4. BoxCarKidd

    BoxCarKidd Road Train Member

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    I thank legal is two pounds per minute in that case, it's in the CDL book. Acceptable to me? No.
    Columbia's have a mob of air pressure switches in the dash, bottom center. Remove the junk drawer then test them with a light an window cleaner. Sometimes bigger leaks are harder to find because the high volume of air may not allow for bubbles to form.
    Cab and suspension leveling valves are often a problem.
     
  5. Hulld

    Hulld Road Train Member

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    Upstate NY
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    Update
    I found leakage behind the dash at the red line coming into to the tractor parking brake valve and the red line coming in to the trailer trolley brake valve.
    I pulled the lines and cut them back and reinserted them but I still have a slight leak at both of them when I use soapy water.
    My question now is are the fittings replace able or do I have to replace both valves?
    Definitely headed in the right direction I had 35 lbs of air pressure left and my cab air bags were still inflated after 13 hrs.
     
  6. Heavyd

    Heavyd Road Train Member

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    Over night leak downs are a tricky situation. If you can hear a leak, that is a defect that must be repaired. In Ontario they say your system must be able to build air from 85psi to 100 psi while the engine is at 600-900 rpm in under 2 minutes. If it takes longer, that is a defect. Then, with a full charge, shut off the engine, release the brakes and make a full brake application and wait for the air pressure to settle, then watch for one minute to see the air pressure drop. I think you are allowed 4 psi per minute for a truck and trailer. If you pass that you are legal. Losing air over night now becomes one of those PITA things you can spend a lot of time and money chasing.
     
  7. Smellfunny

    Smellfunny Road Train Member

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    I am fighting air leaks for a customer with a 2000 Century right now. Replaced his park brake valve and his manifold. The fittings on some park brakes are replaceable on some they are not. If they are able to screw out you can replace them. Get compression style fittings to go back in the place if you can. The customer I am working on now has a hard time understanding that if you fix leak A then Leak B is going to start. I finally explained it to him like those old cartoons where you are in a submarine and you have a leak and you put your finger over the hole then another one pops up. Then another.. It is going to go to the weakest link until you repair them all. But there are a lot on a truck. Especially on a Freightliner Century or Columbia. Good Luck
     
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