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4x4 experts your help is wanted, please

Discussion in 'Truck & Equipment Repair' started by elite1msmith, Dec 4, 2008.

  1. elite1msmith

    elite1msmith 2000 Club Member
    from chicago
    Messages: 2,762

    ok , 94 dodge ram 2500 CTD

    when shifting form 4wheel back down to 2 wheel drive.

    I notice that the 4x4 light can stay on for 4 or 5 mins after i have moved the shifter. As i understand it, the light goes on when the axle locks up. the axle is staying locked up for extra time, becasue the vacum pressure could be low, or maybe the acctuator is getting old.? i understand this part


    heres the kicker..... when i shift into 4x4 the truck seems to pull hard to the right. when im in 2 , it pulls slightly right , but its twice as bad in 4 wheel... i assume i need to get an aligment, with the extra plow weight adding to the effect (yes there is lots of balast)

    so im in 4 and i shift back into 2 wheel. the lever shifts just fine, but the light stays on..... then i start hereing a strage hum, that only happens when im shifted into 2 wheel, but 4x4 light is still on.

    so after a few mins of it, im driving , and out of no wear a large thump for the frond end. the only way i can descripe it is drive in a construction area thats doing road surfaceing... you know when you hit that 2 inch lip, and load bang and suspention throwing you up in the air.... and every time you ouch.....

    thats what it feels like, then your in 2 wheel drive and the hum is gone


    what do you expects think? B&B?
     
  2. theplowmeister

    theplowmeister 2000 Club Member
    from MA
    Messages: 2,550

    Bad vacuum actuator makes the bang when the collar finally disengages the shaft. The pulling, 1 tire different or low on air
     
  3. elite1msmith

    elite1msmith 2000 Club Member
    from chicago
    Messages: 2,762

    really, ?/ that little acctuator , makes that BIG bang that shakes my entire truck?
     
  4. streetsurfin'

    streetsurfin' Senior Member
    Messages: 770

    It's the movement of the collar from over both axles to just one that releases the torque between the two axles, and that jars the truck. When you shift out of four wd, back the truck up while moving steering wheel left and right. It may unlock quicker for you then. Look for a kinked vacuum line, or a corroded switch on top of the transfer case. There is one line with a filter on the end, near the right side firewall, which is an intake for the vacuum system. Make sure it hasn't melted due to the exhaust or kinked or been plugged with dirt. A vacuum gauge brought into the cab with a long hose hooked up at the actuator should tell you if the vacuum signal is building too slowly causing the lag. If the vacuum is built up quickly and it still hangs the forks of the actuator may be bent or the shift motor shaft bent or other problem there.You should have 10-20 in. vacuum at the outboard most shift motor port. If no vacuum there when shifted into two wheel drive, then look for vacuum system, if vacuum ok, then look at axle/ shift motor (actuator).
     
    Last edited: Dec 4, 2008
  5. elite1msmith

    elite1msmith 2000 Club Member
    from chicago
    Messages: 2,762

    ok so basicly check for the vacum, and compair with repair manuel specs, ? there are two lines that go to the actuator, the outer one , towars the tire is the on that locks the 4x4 on , i have used a hand pump and done it manuelly before... so the left one towards the driver pulls it back in 2 wheel? so whic line am i checking? sucktion power on the left or how quick it releases on the right? and this makes the entire thing shake...nuts do you think the arm is bent?
     
  6. streetsurfin'

    streetsurfin' Senior Member
    Messages: 770

    You want to check that you have vacuum in the line that pulls it into two wheel drive and by your statement I take that to be the driver side hose . If you have vacuum in the hose, then apply vacuum to the shift motor with a mighty vac and see if it will disengage as you rotate the wheel. I just looked under my 96 and see the axle is reversed from my 85 (the book from which I quoted), so the "outboard port" may not apply.
     
  7. elite1msmith

    elite1msmith 2000 Club Member
    from chicago
    Messages: 2,762

    yes it is the drivers side... ok ill check that in the morning , thanks for your help

    i know that it is shifting back and forth , it just takes a while, so the bang feeling is the collar moving to slowly?
     
  8. ticki2

    ticki2 Senior Member
    from NH
    Messages: 175

    .
    It could also be that the actuator shaft is sticking . This would cause the banging as you discribe because the shift is taking place while you are under load long after you have shifted. You can take off the cover and see if the shaft is moving freely . There is also a solinoid on top of the transfer case that contols the vacuum to the actuator.
     
  9. elite1msmith

    elite1msmith 2000 Club Member
    from chicago
    Messages: 2,762

    if i remember right , if you take off the cover the shaft comes out with it
     
  10. rocknrollrednec

    rocknrollrednec Senior Member
    Messages: 108

    the shaft, and shift fork, will come out with the cover. apply vacuum to the ports, one at a time, and see if it moves freely. if it does, you probably have vacuum leaks too. my 87 had the same setup, and I was sick and tired of chasing down vac leaks, and having the front end try to disengage when I had my foot to the floor for more than a few seconds.
    so I replaced the shaft with a bolt, too measurements and shimmed the fork in the "engaged" position with washers, ditched all the vac crap, and put on warn hubs. (if the axle ever breaks, I'll rob one from an 80's chevy)

    can you put locking hubs on a 94?
    you could save yourself some grief, and buy a manual actuator (cable, instead of vac) from Posi-Lock.
     
  11. ticki2

    ticki2 Senior Member
    from NH
    Messages: 175

    Yes it does , also check the light switch shaft that it isn't sticking and preventing the actuator shaft from moving easily .