AF: 1988 dodge w150 318 4wd doesn't work but T case is engaging | Allpar Forums
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1988 dodge w150 318 4wd doesn't work but T case is engaging

Discussion in 'Pre-1994 trucks, commercial vehicles' started by upser145, Dec 10, 2017.

  1. upser145

    upser145 Member

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    my 1988 w150 that I haven't had for long i recently found out the 4wd isn't working it has manual locking hubs and i made sure to lock them and i can put the tcase in 4wd and get under the truck and can no longer turn the front driveshaft by hand but the front tires won't pull so it seems the tcase is engaging. I've heard some people say to lock my CAD and it could fix it but being that I have little experience with a 4wd front end I'm not sure if locking it would be good or possibly a bad idea or what exactly it does any help would be greatly appreciated. also noted the first time i ecer put it in 4wd it felt almost as if it was popping in and out of 4wd and kinda hopped when i hit a dry patch of road like it would if it was in 4wd but I've never been able to get the fronts to spin
     
  2. Devildodge

    Devildodge Active Member

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    Do you know if the manual hubs where added by someone. If you have C.A.D. then someone did. The C.A.D. Did away with the manual hubs.

    If you do still have C.A.D. you can lock it yourself, or buy a kit.

    V10 RAM getting some due rest and rectification of Pennsylvania abuse. (at https://www.allpar.com/forums/threads/v10-ram-getting-some-due-rest-and-rectification-of-pennsylvania-abuse.164786/ )

    You can check out this link, it is my challenge with C.A.D.

    If your truck came with manual hubs it wouldn't have C.A.D., so if it does I am not real sure why someone would do that modification.

    Let us know some more info and we will be glad to help.
     
  3. Devildodge

    Devildodge Active Member

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    The C.A.D. is on the long axle tube under the truck. Held on by 4 bolts and would have a vacuum bulb and a switch.

    Does your 4wd light come on?

    If you do have C.A.D. then you may have a broken fork.
     
  4. upser145

    upser145 Member

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    I am not sure if they were added or not. as soon as i can find the cad and figure some more info out i will update thanks for your time guys!
     
    Devildodge likes this.
  5. pt006

    pt006 Active Member

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    The axle disconnect system is a 2 piece axle connected by a sliding spline. When the spline is disengaged, the inner axle spins, but not the outer axle. When the spline is engaged, the inner axle turns the outer axle and now you have 4WD. The spline is slid back and forth by a fork which is driven by a vacuum piston/diaphragm. When vacuum is applied to either of the 2 vacuum ports, the piston/diaph. will move one way or the other [engaged or disengaged]. When the spline is fully engaged it hits a switch and an electrical signal is sent to the dash to light up the dash screen. Says 4WD ENGAGED [I think].

    Be aware that the sliding spline will not disengage if there is tension on the axle. Rolling back and forth will help.
    Also, the sliding spline will not engage if the splines of one axle do not line up with the splines of the other axle. Rolling back and forth will help. It important that the dash light works. This verifies that the splines are fully engaged. NEVER operate in 4WD unless the dash light is on, because if the spline is only partially engaged then serious damage can be done to the sliding spline or the axle spline.

    The truck must be running to produce vacuum. Check hoses for leaks. ----- good luck-----
     
    NYBo likes this.
  6. upser145

    upser145 Member

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    Ok so i Have two 1988 rams one the 4wd works one doesn't the one it doesn't has manual hubs that were added and it still has the cad does the cad have to be locked for it to work with manual hubs? also the one that the 4wd works has stock auto hubs and i can't move the cad by hand but on the one with no 4wd i can crawl under it and move the CAD some by hand like somethings loose not sure what that could mean.
     
  7. Devildodge

    Devildodge Active Member

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    I am not 100% sure I follow you. But in the one with auto hubs, you say you can move the CAD...Sounds like broken fork. On the one with manual hubs, but still has CAD, it either has to be locked in place or has to operate as intended. Hope that makes sense.

    Edit. I read it again and realized you said the one worked. I would venture to guess the one with the manual hubs was someone' attempt at making it better and they never finished the job.
     
  8. upser145

    upser145 Member

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    Yep thats what i was thinking someone started and never finished, so if the fork is broken could i still just lock the CAD or would the fork have to be replaced
     
  9. Devildodge

    Devildodge Active Member

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    The fork is what holds the collar over. You can buy the lockout kit or you can do it by moving the e clips. But if it is a broken fork that will have to be replaced
     
  10. upser145

    upser145 Member

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    Does anyone know of a good tutorial or book with good info on replacing the fork in the CAD i have everything i need but would like some kind of instruction as it is my first time doing this
     
  11. Devildodge

    Devildodge Active Member

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    Remove electrical connector and vacuum lines. Remove four bolts holding the cover.

    Remove e clips and slide actuator rod out.
    Shift fork will come off as well.
    Finished with removal.

    Slide actuator in cover and through new shift fork.
    Replace e clips.
    Replace gasket with new and slide over fork and set in place over cover.
    Slide fork over collar.
    Return 4 bolts to the cover.
    Hook up electrical connector and vacuum lines.
    Refill with lube.

    You tube has videos and any of the manuals that can be bought for the truck can be used.
    Also posi lok website will have a tutorial.

    Easy job but you may break off the bolts (I did) so you might want to be prepared to replace them.

    Good luck.
     
  12. upser145

    upser145 Member

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    I thought i would be able to find the parts but i have been unable to find them any idea where i could order them from?
     
  13. ImperialCrown

    ImperialCrown Moderator
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    Which parts specifically?
     
  14. upser145

    upser145 Member

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    Shift fork and the CAD gasket
     
  15. Devildodge

    Devildodge Active Member

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  16. upser145

    upser145 Member

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    I know someone that has a CAD assembly out of a 2nd gen 1500 i believe that would work correct? and i never pulled the cover havn't had time buti figured something has to be broke in there and figured I'd just go ahead and replace the whole assembly
     
  17. Devildodge

    Devildodge Active Member

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    I would say they are very similar, but not 100 percent sure they are the same. They would surely be close though.

    As it seems, the part number is the same for 1988 to 1999 Rams. And all years from 1985 to 2001 are listed together on most sites.

    Should work, no guarantee.
     
    #17 Devildodge, Mar 10, 2018
    Last edited: Mar 10, 2018
  18. upser145

    upser145 Member

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    Alright thanks im gonna look into it anyone have a part number for the gasket by chance
     

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