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98 w900b wont build air

Discussion in 'Kenworth Forum' started by CAT3412, Jan 23, 2012.

Page 1 of 2
  1. Jan 23, 2012 #1
    CAT3412

    CAT3412 Bobtail Member

    4
    0
    Jan 23, 2012
    Northwest,CT
    0
    Hey all new to the forum here. 98 kw w900b cat 3406e cat tu-flo 750 compressor. Was fine when parked and next morning went to fire up and the truck won't build air. Nothing out of discharge line on top of compressor and minimal air on the inlet. Replaced governor for the hell of it and nothing. I was under the truck with a propane torch heating up the fittings on the lines in case of ice and that did nothing as well. Any ideas? Thanks, Dean
     
    CAT3412, Jan 23, 2012
    CAT3412, Jan 23, 2012
    #1
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  3. Jan 23, 2012 #2
    Les2

    Les2 Road Train Member

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    kicked back in my lazyboy...
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    If you aren't getting any air out of the top and its not pulling air in the intake, your compressor is shot.

    You said you replaced the governor but did you replace it with a new one? If so, then your most likely going to be replacing the compressor.
     
    Les2, Jan 23, 2012
    Les2, Jan 23, 2012
    #2
  4. Jan 23, 2012 #3
    CAT3412

    CAT3412 Bobtail Member

    4
    0
    Jan 23, 2012
    Northwest,CT
    0
    Yeah brand new governor. I was afraid of that, there was no problem with air before. Can the compressor really go sitting overnight?
     
    CAT3412, Jan 23, 2012
    CAT3412, Jan 23, 2012
    #3
  5. Jan 23, 2012 #4
    KaptainKenworth

    KaptainKenworth Bobtail Member

    33
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    Jan 19, 2012
    Alberta Canada
    0
    Sounds like the unloaders in the comp are stuck open.. by removing the plate on the top of the compressor you can access tham..fairly cheap and easy fix if that is the problem....(a quick fix to get you out of a bind,remove the compressor air inlet and spray some penetrating fluid on the unloaders and they may free themselves up)
     
    KaptainKenworth, Jan 23, 2012
    KaptainKenworth, Jan 23, 2012
    #4
  7. Jan 23, 2012 #5
    CAT3412

    CAT3412 Bobtail Member

    4
    0
    Jan 23, 2012
    Northwest,CT
    0
    Alright cool that is the next thing I had in mind. Thanks for the post.
     
    CAT3412, Jan 23, 2012
    CAT3412, Jan 23, 2012
    #5
  8. Jan 23, 2012 #6
    CAT3412

    CAT3412 Bobtail Member

    4
    0
    Jan 23, 2012
    Northwest,CT
    0
    What is actually rebuilt in the unloaders and how do they work? I've never torn into a truck compressor.
     
    Last edited: Jan 23, 2012
    CAT3412, Jan 23, 2012
    CAT3412, Jan 23, 2012
    #6
  9. Jan 23, 2012 #7
    Shade Tree

    Shade Tree Light Load Member

    177
    44
    May 15, 2011
    Galloway Ohio
    0
    The unloaders are valves that have springs on top of them that lift off their seat to allow air to go to the governor and open it or shut it off. Normally what happens over night is the airline check valves get stuck (frozen) and won't allow air to go to the air tanks.
     
    Shade Tree, Jan 23, 2012
    Shade Tree, Jan 23, 2012
    #7
  10. Jan 23, 2012 #8
    bender

    bender Road Train Member

    2,105
    1,356
    Jul 20, 2010
    Don't Kid Yourself
    0
    The parts that actuate the unloaders are serviced with a unloader kit but not the unloader valves themselves. The unloader valves open to stop compressor from pumping air. The compressor cylinder is then open to the intake side when not pumping.
     
    bender, Jan 23, 2012
    bender, Jan 23, 2012
    #8
    CAT3412 Thanks this.
  11. Jan 24, 2012 #9
    Les2

    Les2 Road Train Member

    5,150
    2,288
    Jul 25, 2008
    kicked back in my lazyboy...
    0
    The problem is finding a rebuild kit for the unloaders. I tried this a few weeks ago and had no luck so I ended up searching high and low for a compressor. I have an older model on mine and they seem to be harder to come by, parts or compressor.
     
    Les2, Jan 24, 2012
    Les2, Jan 24, 2012
    #9
  12. Jan 24, 2012 #10
    KW Parts Guy

    KW Parts Guy Light Load Member

    230
    78
    Jul 16, 2011
    0
    Get me your truck ser number and i'll getcha a part number, they're usually as common as rat ####.
     
    KW Parts Guy, Jan 24, 2012
    KW Parts Guy, Jan 24, 2012
    #10
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