Jump to content

  •  

  • Welcome to BigMackTrucks.com

    Welcome to BigMackTrucks.com, the best resource on the Internet for Antique, Classic and Modern Mack Trucks!  

     

    Please login or register to take advantage of everything BMT has to offer.  Memberships are Free and offer many benefits:

     

    • Start new topics and reply to others
    • Subscribe to topics and forums to get automatic updates
    • Showcase your trucks in our Garage
    • Photo Gallery, Member Blogs and much more...
    • Add events to our community calendar
    • Create your own profile and make new friends
    • Customize your experience!
    • Mack Dealer and Corporate personnel can contact the ADMIN after registration for access to the Dealer Forums.

    If you are having trouble logging in or haven't received your validation email, you can post as a guest in the Guest Forum.


    login  register
    Guest Message by DevFuse
     

    Photo

    Air Dryer/compressor Questions



    • Please log in to reply
    14 replies to this topic

    #1 OFFLINE   Truck992

    Truck992

      Old Iron Expert

    • Porch Pup
    • PipPipPipPipPipPipPip
    • 51 posts
    • Make:Mack
    • Model:CH613
    • Year:1998

    Posted 09 September 2007 - 07:19 PM

    I installed a new air dryer on my 98 CH. Right after it spits it sounds like air is leaking from the compressor but only for a few seconds. Why does it do this??? There doesnt seem to be any leaks around the compressor. Also the compressor charges my system up to 130PSI. Is there a way to dial it down???? Is there any special way to install the air dryer besides mounting it and connecting the 3 air lines and plug.? It was pretty simple...but almost too simple.
    Thanks for your help.
    Rob w.

    #2 OFFLINE   ThaddeusW

    ThaddeusW

      MadMacks

    • Pedigreed Bulldog
    • PipPipPipPipPipPipPipPipPipPip
    • 1,778 posts
    • Location:Ozone Park, New York City
    • Make:Mack
    • Model:B61
    • Year:1961

    Posted 10 September 2007 - 01:42 AM

    Rob,
    The three lines and plug are all thats needed. As for the air leaking sound, the governor sends out positive pressure to hold the unloader valve in the compressor open. This stops the charge cycle and that same air signal also triggers the purge cycle of the air dryer.
    The governor does have an exhaust port, that might be the leaking sound but thats normal. 130 PSI sounds normal as the pressure relief valves in the brake system are set at 150 PSI. Turning that pressure down is possible by adjusting the governor cut out pressure via a screw on one end. But some governors are not adjustable like the D2-A from Bendix.

    Here are the instructions for the D2 from the Bendix website:

    To raise the pressure settings, turn the adjusting screw
    counter-clockwise. To lower the pressure settings,
    turn the adjusting screw clockwise. Note: Be careful
    not to overadjust. Each 1/4 turn of the adjusting screw
    raises or lowers the pressure setting approximately 4
    psi.
    -Thad
    What America needs is less bull and more Bulldog!

    #3 OFFLINE   Truck992

    Truck992

      Old Iron Expert

    • Porch Pup
    • PipPipPipPipPipPipPip
    • 51 posts
    • Make:Mack
    • Model:CH613
    • Year:1998

    Posted 10 September 2007 - 05:48 PM

    Thanks for the help Thad!!

    #4 OFFLINE   HK Trucking

    HK Trucking

      BMT Certified Know-It-All!

    • Pedigreed Bulldog
    • PipPipPipPipPipPipPipPipPipPip
    • 1,557 posts
    • Location:Appleton WI

    Posted 10 September 2007 - 06:15 PM

    I'd leave it at 130.

    That extra 10 lbs. pressure isn't going to hurt anything, and it will give you an extra reserve of air.
    "If You Can't Shift It Smoothly, You Shouldn't Be Driving It"

    #5 OFFLINE   CML Service

    CML Service

      BMT Veteran VIP

    • Big Dog
    • PipPipPipPipPipPipPipPip
    • 151 posts
    • Location:Hamden CT
    • Make:MACK
    • Model:B , R , DM ,U ,CH
    • Year:1954 - 1995

    Posted 12 September 2007 - 04:26 AM

    Some of the newer air driers like the Bendix AD-SP have a longer purge that will sound like a air leak from the bottom valve, but only for 10 seconds or so.
    Chuck

    #6 OFFLINE   Noid93

    Noid93

      Old Iron Expert

    • Porch Pup
    • PipPipPipPipPipPipPip
    • 68 posts
    • Location:Arkansaw, WI
    • Make:Mack
    • Model:CH613
    • Year:1997

    Posted 13 September 2007 - 12:03 AM

    Unless the destroking process on the air compressor takes longer than the purge, It will continue to pump air untill the destroking valve hold the valves open on the air compressor. Just had a 3176 cat in a t600 KW (part of Maxvilles fleet) that would continue to pump all day long. The culprit, a collapsed line from a governor to the compressor, but if your mack is like mine, the gov is bolted to the comp. Also, The o rings on the destroking valves could be old and cracked, I just ordered a "destroking kit" for the bendix tf 550 air compressor on that cat(the same as on my truck) that consists of a gasket and push rods with new o rings for a whole 15 dollars. Those valves are just under the cover on the head of the comp(right on top). If you need i can get a part #. Let me know.
    There Is No Replacement, For Displacement!!!!!

    #7 OFFLINE   Truck992

    Truck992

      Old Iron Expert

    • Porch Pup
    • PipPipPipPipPipPipPip
    • 51 posts
    • Make:Mack
    • Model:CH613
    • Year:1998

    Posted 13 October 2007 - 04:16 PM

    OK gang i still need your help. I installed a new unloader kit in my 98 CH. It didn't really make much difference but my air dryer is doing silly shit. It is a new dryer from the Mack dealer....When i start the truck with 0psi its fine until the dryer spits at about 125 (sometimes 130) then it ticks like a bomb for 5 seconds then it hiss's air until the red needle is down to 100. Air builds back up (dryer still hissing air) until it hits 125/130 again. Then it starts over. It seems to hiss air all the time and the compresor is just doing it's normal thing. Is the new dryer bad?? The parts guy at Mack said they are really never bad out of the box.


    thanks for the help
    Rob W.

    #8 OFFLINE   theakerstwo

    theakerstwo

      BMT Certified Know-It-All!

    • Pedigreed Bulldog
    • PipPipPipPipPipPipPipPipPipPip
    • 2,132 posts
    • Location:mounds okla
    • Make:mack
    • Model:b61
    • Year:1957

    Posted 13 October 2007 - 05:39 PM

    OK gang i still need your help. I installed a new unloader kit in my 98 CH. It didn't really make much difference but my air dryer is doing silly shit. It is a new dryer from the Mack dealer....When i start the truck with 0psi its fine until the dryer spits at about 125 (sometimes 130) then it ticks like a bomb for 5 seconds then it hiss's air until the red needle is down to 100. Air builds back up (dryer still hissing air) until it hits 125/130 again. Then it starts over. It seems to hiss air all the time and the compresor is just doing it's normal thing. Is the new dryer bad?? The parts guy at Mack said they are really never bad out of the box.
    thanks for the help
    Rob W.



    Where does the air leak fromand what kind of drier is it? glenn
    glenn akers

    #9 OFFLINE   fjh

    fjh

      BMT Certified Know-It-All!

    • Pedigreed Bulldog
    • PipPipPipPipPipPipPipPipPipPip
    • 1,303 posts
    • Location:bc canada

    Posted 13 October 2007 - 06:58 PM

    Unless the destroking process on the air compressor takes longer than the purge, It will continue to pump air untill the destroking valve hold the valves open on the air compressor. Just had a 3176 cat in a t600 KW (part of Maxvilles fleet) that would continue to pump all day long. The culprit, a collapsed line from a governor to the compressor, but if your mack is like mine, the gov is bolted to the comp. Also, The o rings on the destroking valves could be old and cracked, I just ordered a "destroking kit" for the bendix tf 550 air compressor on that cat(the same as on my truck) that consists of a gasket and push rods with new o rings for a whole 15 dollars. Those valves are just under the cover on the head of the comp(right on top). If you need i can get a part #. Let me know.


    You may have bad unloder orings in the compressor head depending on your compressor they can be easy or hard to change!
    If you have a 700 bendix its easy if you have a 500 bendix its dificult!
    take the small line off the air drier while the compressor is pumping between 90 and 130 if there is air coming out the line the problem is in the unloader !

    #10 OFFLINE   Truck992

    Truck992

      Old Iron Expert

    • Porch Pup
    • PipPipPipPipPipPipPip
    • 51 posts
    • Make:Mack
    • Model:CH613
    • Year:1998

    Posted 13 October 2007 - 09:20 PM

    Where does the air leak fromand what kind of drier is it? glenn

    The air is coming from the valve or hole at the bottom of the dryer. I dont recall what model Bendix it is.

    #11 OFFLINE   Truck992

    Truck992

      Old Iron Expert

    • Porch Pup
    • PipPipPipPipPipPipPip
    • 51 posts
    • Make:Mack
    • Model:CH613
    • Year:1998

    Posted 13 October 2007 - 09:24 PM

    There is one thing i forgot to mention...when i put the new unloader kit in I had a problem with the gasket leaking and took the cover off again. I did notice the piston on the left side popped up with the new spring and the right one (the one to the front of the truck) didn't pop up and almost seemed stuck in the hole. I did grease the new ones up with the grease in the kit before i put them in.. Was it supposed to pop up when i took the cover off????

    #12 OFFLINE   theakerstwo

    theakerstwo

      BMT Certified Know-It-All!

    • Pedigreed Bulldog
    • PipPipPipPipPipPipPipPipPipPip
    • 2,132 posts
    • Location:mounds okla
    • Make:mack
    • Model:b61
    • Year:1957

    Posted 13 October 2007 - 09:47 PM

    There is one thing i forgot to mention...when i put the new unloader kit in I had a problem with the gasket leaking and took the cover off again. I did notice the piston on the left side popped up with the new spring and the right one (the one to the front of the truck) didn't pop up and almost seemed stuck in the hole. I did grease the new ones up with the grease in the kit before i put them in.. Was it supposed to pop up when i took the cover off????


    If it drains the air tank down till the governor kicks back in and it is a ad4 or a ad9 bendix you have a check valve in the drier draining the 1st tank back in to the drier and out of the purge valve. The ad 4 has a plastic flapper for a check valve inside and you have to tear down to replace and the ad9 will have a screw in check valve on the bottom on the inlet port of the dier and can be changed from the bottom. glenn
    glenn akers

    #13 OFFLINE   Truck992

    Truck992

      Old Iron Expert

    • Porch Pup
    • PipPipPipPipPipPipPip
    • 51 posts
    • Make:Mack
    • Model:CH613
    • Year:1998

    Posted 14 October 2007 - 05:48 AM

    The part # on the box is 745 800887 it says AP-SA Bendix air dryer it doesnt have a number after AP. I'll look on the air dryer itself on Monday. The old one doesnt say either. The new one does have a plastic flapper on the bottom.

    So what you guys are telling me the air dryer is probably the problem and not the compressor or unloader?? It's still under warranty. Also the Mack dealership said I can bring it in and they'll test it.

    thanks again
    Rob W.

    #14 OFFLINE   Truck992

    Truck992

      Old Iron Expert

    • Porch Pup
    • PipPipPipPipPipPipPip
    • 51 posts
    • Make:Mack
    • Model:CH613
    • Year:1998

    Posted 14 October 2007 - 05:51 AM

    My bad ...it's AD-SP

    #15 OFFLINE   theakerstwo

    theakerstwo

      BMT Certified Know-It-All!

    • Pedigreed Bulldog
    • PipPipPipPipPipPipPipPipPipPip
    • 2,132 posts
    • Location:mounds okla
    • Make:mack
    • Model:b61
    • Year:1957

    Posted 14 October 2007 - 08:39 AM

    My bad ...it's AD-SP


    I sorry but i cant help you on the ad sp i know what it is but have never wored on it but if the dier is draining the wet tank it sounds like the deir is defective. glenn
    glenn akers




    0 user(s) are reading this topic

    0 members, 0 guests, 0 anonymous users