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ZF-5 transmission not engaging

Discussion in '6.9L IH & 7.3L IDI Diesels' started by Skinny Lennie, Dec 24, 2019.

Replace transmission

  1. Yes

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  2. No

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  3. Sell truck

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  1. Skinny Lennie

    Skinny Lennie Registered User

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    I have a 94 F250 4x4 7.3idit 5 speed manual transmission. I bought the truck non running and after I got it running it drove for a couple hundred miles expect reverse wouldn’t engage. While driving if I let off the fuel the RPMs would drop and I would coast but when I got back on the fuel it would pick back up and go on. Then one day it drove until I reached 3rd and it just revved then caught violently so I stopped. After that it was hit and miss if it would engage so I engaged the transfer case with hubs unlocked and it would go just fine just slow. Does anyone know what’s going on? Any advice would be great before I sell this truck or find a transmission thanks
     
  2. Garbage_Mechan

    Garbage_Mechan Garbage Mechanic

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    My first thought is that the Dual Mass Flywheel is failing but that doesn’t explain why putting it in 4 wheel makes any difference
     
  3. Garbage_Mechan

    Garbage_Mechan Garbage Mechanic

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    So another thought is the transfer case. I have had a BW1356 do something like this. The oil pump failed, spun around and wiped out the plastic shift fork liners. Then it would jump out of gear. I drove about 30 miles with my foot on the transfer case shifter keeping it engaged. However this wouldn’t easily explain the freewheeling deceleration.
     
  4. Garbage_Mechan

    Garbage_Mechan Garbage Mechanic

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    What kind of noises are you getting?
     
  5. Skinny Lennie

    Skinny Lennie Registered User

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    When it drove and I let out of the fuel it would sound like it was rattling as the rpms dropped it pretty much was like I put it in neutral until I got on the fuel again
     
  6. Randy Bush

    Randy Bush Full Access Member

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    That would not explain the not going into rev? I would tend to think the transmission. I wonder when shifting the transfer case if he can feel it locking in each range?
     
  7. Skinny Lennie

    Skinny Lennie Registered User

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    It won’t go anywhere in 4hi but in 4lo it will go. Also reverse works in 4lo hubs unlocked and locked
     
  8. franklin2

    franklin2 Full Access Member

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    Any oil in the transfer case? They like to develop leaks. When the oil gets low they overheat and have problems like the other posters mentioned. They are not hard to change and a used one is not too expensive.
     
  9. Randy Bush

    Randy Bush Full Access Member

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    sounds like transfer case issue then.
     
    SlippyRider and troutwest66 like this.
  10. Skinny Lennie

    Skinny Lennie Registered User

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    Even when the transfer case is out of gear it won’t go. I don’t know much about transmissions. So the transfer case plays a role with the transmission all the time?
     
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  11. franklin2

    franklin2 Full Access Member

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    Any power that goes though the transmission, has to go through the transfer case, whether it's in 2wd or 4wd. If the transfer case is in neutral, you are not going anywhere. Putting the transfer case in neutral is good for towing the truck with all 4 wheels on the ground, since it disconnects everything from the driveshaft.
     
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  12. 79jasper

    79jasper Chickenhawk

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    Definitely the tcase. Like garbage said, the shift fork pads come off. Typically mine this has happened before anything else. I've had 3 or 4 do exactly this. Some in early stages would slip if you left off the throttle.

    Sent from my SM-N960U using Tapatalk
     
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  13. Skinny Lennie

    Skinny Lennie Registered User

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    Ok thanks! I’ll check it out what fluid do y’all recommend for the t case and transmission?
     
  14. Skinny Lennie

    Skinny Lennie Registered User

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    Would fluid solve this problem or does it sound like I need to replace the whole t-case?
     
  15. DaveBen

    DaveBen Supporting Member Supporting Member

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    Drain the existing fluid and if it has ANY metal bits in it, the transfer case needs a rebuild.
     

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