YUUUGE problems in my Transmission/Tcase/Diff ????? Its a mess

Discussion in 'Engine & Drivetrain' started by Shibbershabber, Nov 7, 2019.

  1. Shibbershabber

    Shibbershabber Member

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    Ok... so... 1999 Yukon 5.7, 4x4, 4L60E

    First, thinking about this in hindsight... had been making a light grinding noise ever so slightly and for only a second while taking off from a stop... mostly while turning and thought it was a tire rubbing. Sort of like what a car sounds like with a bad CV axle.

    FF to tonight, take off from a stop, going straight, I hear the same noise, but it does not stop and as I continue forward it escalates to an ominous grinding slam within 2-3 seconds.
    Engine continues to run, I give it some gas but nothing happens. I coast into a parking lot and get a tow home.


    Here is where its at now.

    In PARK, the truck rolls as if its in NEUTRAL

    From PARK I shifted into REV with grinding, it seems to engage and moves backwards, feels like it at least.

    Shifting into the forward gears, I can hear a rotating sound, like something engaged. I look underneath and the drivelines are both spinning but there is no engagement of the wheels

    Shifting back down, it will not engage REV at this time... going into PARK gives a higher pitched grind, but still rolls freely.


    Trans was serviced last year with nothing abnormal found. Fluid looked good at that time and still did recently. No other signs of trouble, no other grinding or slipping.

    Sure there is no shortage of people who will try to sell me what they have to solve this issue, but In the interest of saving some money I want to narrow it down some.

    No movement at wheels while the driveline spins away makes me thing the read end went.
    BUT the grindings and noises from the transmission make me things its something inside the trans itself.

    Could both have blown out?

    I suppose I can open up the rear differential and see how things liik in there
     
  2. swathdiver

    swathdiver Full Access Member

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    RWD or 4x4? Symptoms make it seem like a transfer case issue if you have one...

    I would chock the wheels and jack up the rear with the driveline in neutral and rotate the driveshaft by hand with my ears open.
     
  3. Shibbershabber

    Shibbershabber Member

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    Its a 4x4

    leaning towards rear end right now...considering that the driveline spins while in gear, just not engaging the diff.

    Ill pop the cover off tonight and see what it looks like in there. My guess is there is going to be a lot of debris....
     
  4. PNW VietVet

    PNW VietVet Full Access Member

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    When you remove the rear diff cover make sure you have safety glasses on for the metal debris that may fly out. I think you may have rear diff and transfer case problems. Getting it all opened up should take the guess work out of it.
     
  5. Shibbershabber

    Shibbershabber Member

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    I just went out and tried to see what it would do in 4wd...

    So I can drive in forward and reverse if I put it into 4hi....... go back to 2wd and I have nothing...

    Looking a lot more like its the rear end
     
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  6. PNW VietVet

    PNW VietVet Full Access Member

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    I believe you are on to something. That is gonna be ugly inside that diff. Be prepared for the grey fluid to flow out.
     
  7. Shibbershabber

    Shibbershabber Member

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    Well, opened it up and it is definitely the differential..... or whats left of it anyway

    Big chunks in there. Getting it done today, $900........... but beats 2x that for a tranny........


    This is pretty far above my pay grade, anyone have a guess as to what caused this to happen?

    20191111_143827.jpg
    20191111_144003.jpg
     
  8. 96-2D-Hoe

    96-2D-Hoe Full Access Member

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    I had a crack in my diff body that is almost identical to the shape of what's left of yours in the last pic. I'd say whatever caused it be thankful it didn't grenade on the freeway, I was very happy I found mine before it did.
     
  9. PNW VietVet

    PNW VietVet Full Access Member

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    Cause? Likely age and mileage. You never said mileage I believe. Don't know the maintenance record on it either so maybe not taken care of with fluid changes in a timely manner?

    Or your 10 second quarter mile launches at the drag strip had something to do with it. :chewie:
     
  10. Shibbershabber

    Shibbershabber Member

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    Hahaha no time at the drag strip for me.

    Its got 180k on it. Not sure of the service history before I got it. However, the fluid didnt look too bad... still pretty transparent.

    Oh well. One less thing to worry about in the future I suppose.
     

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