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Front tires not spinning while in 4x4 '98

Discussion in 'Dodge 4x4' started by d2stephen, Mar 11, 2012.

  1. d2stephen

    d2stephen
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    Helping a buddy work on his '98 1500 4x4 Sport, truck was intermittent in locking into 4x4, but now wont at all. Just replaced actuator, and ran a few new vacuum lines because one was pinched shut. Not really too sure what else to do. We put it in 4x4, the light turns on, front axle spins and everything. However, the front tires do not have any power going to them. Not really sure what else could be causing this. There is vacuum in the lines, not crazy strong, but its there. Anyone have any input on this? Really digging at the bottom of the barrel for ideas...
     

  2. jprtroy

    jprtroy
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    So, your saying that the front drive line spins when the transfer case is in 4X4, and that the wheels don't spin under power? If this is the case, I'm thinking you could have 1 of 2 problems. Not enough vacuum to pull the CAD to engage, or broken axle shaft.
    You need to verify how much vacuum is at the cad, (vacuum gauge) I don't know what that reading should be, (My truck produces 30hg vac)
    Jack the truck up, all four wheels off the ground, rotate the front left tire. You should see the front driveline rotate with the tire. If not, then something is broken in the axle. (Unless you have locking hub, if so lock them) If the driveline rotates when you spin the wheel, then this'll tell you that the driveline is connected to the wheel, nothing broke on that side, and you should look at the vacuum.
    I think the right side wheel is outside the cad and it won't engage without vac, so the right wheel should spin freely untill you apply vacuum to engage the cad.
     

  3. v10sport

    v10sport
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    Sounds like the cad collar isn't sliding over all the way.
     
  4. d2stephen

    d2stephen
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    Thank you. I'll hook up a vacuum gauge to it as soon as he gets back to work. When I pull the small vacuum hoses off they have suction, but it feels very little. I was concerned that wasn't enough to pull the collar over, but didn't know how much vacuum was needed. I appreciate you telling me how much vacuum yours has, that will give me a general idea of what we need to be at.
     
  5. d2stephen

    d2stephen
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    Okay, quick update. Hooked a vacuum gauge up to the lines on the bottom of the truck, gauge read 16, then we checked the hose near the back of the intake manifold, that every other vacuum line hooks into, and that only read 16 as well. Followed all lines from there and come to find out some how the line running to the HVAC had been cut. So we re-ran that hose, started the truck, and now it reads around 17.5 of vacuum. Still not switching into 4x4 though. Later today we will be jacking up all 4 tires as mentioned and testing that, and we will also be taking the fork assembly on the axle just to double check everything is well down there.
     
  6. Wh1t3Nukle

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    I'd recommend you still verify integrity of ALL vacuum lines in the system. Even the line back to the evap cannister is part of that system, correct?

    This might help further.
    http://dodgeram.org/tech/repair/4X4/4x4_engagment.htm
     
  7. d2stephen

    d2stephen
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    Correct. We checked and this line did have a cut in it. Replaced it and it went from 15 vacuum to 17.5 vacuum. Still no where near enough to switch into 4wd. Guess from here on we will have to check every hose....
     
  8. wheelrr15

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    i had this problem a while back. it turned out that one of the teflon pieces on the shift fork that slides in the collar had broke off and the light would say it was engaged but it was not. the fork was binding somehow and not letting the collar slide all the way over. when you pull the fork out to check it just check to see that the plastic bushing is still inside the axle shaft as well. mine was broken and would allow the collar to slide over either. maybe this will help ya out
     

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