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  1. #1
    Bobtail Member
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    Low air problems on a 2004 Volvo 670

    Air compressor went bad, oil in tanks. Replace with reman compressor, new governor, new air dryer, cleaned tanks and air hoses.



    The problem is that from 0 to 70 pounds of pressure all tanks fill fine at idle. Accelerate motor to 1500 rpms all tanks fill slowly to 120 psi. When I let truck idle back down to 600 rpms, the primary tank drops to 70 psi within 90 second. The secondary tanks hold their air for a while then eventually drops to 90 to 100 psi.

    I have checked for air leaks with the truck off and had assistance checking for air leaks while holding the brake in. Results, couldn't hear any.

    While driving, my truck holds air at 120 psi and while in stop and go traffic or a stop light the same thing happens as I described earlier to the primary tank.

    Can someone give me some insight to this annoying problem.

    Thank you!

  2. #2
    Road Train Member Heavyd's Avatar
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    Still have a leak somewhere. Some leaks are so bad they make no noise. Keep looking.

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  4. #3
    Road Train Member blanco's Avatar
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    leaking brake chambers? have you listened for air leaks with engine off?

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  6. #4
    Road Train Member bender's Avatar
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    Is your main air line off the air compressor hard piping or a braided stainless flex line?
    Keep in mind that the check valve between primary and secondary air tanks has a rubber seat and can be affected by oil in the air system (swelling and deterioration).

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  8. #5
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    Grab a bottle of soapy water and start looking for the leaks. Listening only gets you so far.

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  10. #6
    Bobtail Member
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    Quote Originally Posted by scsapril69 View Post
    Air compressor went bad, oil in tanks. Replace with reman compressor, new governor, new air dryer, cleaned tanks and air hoses.

    The problem is that from 0 to 70 pounds of pressure all tanks fill fine at idle. Accelerate motor to 1500 rpms all tanks fill slowly to 120 psi. When I let truck idle back down to 600 rpms, the wet tank drops to 70 psi within 90 second. The primary & secondary tanks hold their air for a while then eventually drops to 90 to 100 psi.

    I have checked for air leaks with the truck off and had assistance checking for air leaks while holding the brake in. Results, couldn't hear any.

    While driving, my truck holds air at 120 psi and while in stop and go traffic or a stop light the same thing happens as I described earlier to the primary tank.

    Can someone give me some insight to this annoying problem.

    Thank you!
    Thank you all for your responses. The problem turned out to be, my turbo actuator was leaking air.

  11. #7
    Road Train Member
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    mine did that too, I only found it because I tried to hear leaks while it was running, which you would think would not be the thing to do.

  12. #8
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    Quote Originally Posted by scsapril69 View Post
    Thank you all for your responses. The problem turned out to be, my turbo actuator was leaking air.
    Ouch $$$$$$$$$. Did you have to buy a new actuator or was there a repair kit for it? Mine is doing the same thing, ive just been putting it off.