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Changind Diff Fluid ???

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by reddog64, Mar 27, 2001.

  1. reddog64

    reddog64 1/2 ton status

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    It sounds easy... I just want to make sure I do it right... I need/want to service my front and rear ends before I burn up something... I have a 78 Jimmy w/a D44 front and a 12 bolt rear... I think the rear has that gov-lock crap...
    Let me see if I have this right... in order to change the fluid in fornt rear, Iall I have to do is remove the cover, ket it drain, replace the seal, bolt on the cover, fill with fluid and I'm set right??? What fluid do I use... is there an additive for the rear??? How can i tell if it's the gov-lock thing???

    Um... yes officer I know it's too big...
     
  2. Ditchdigger

    Ditchdigger Registered Member

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    Thats about it, Make sure when you pull the cover to watch for any chunks, metallic color or shavings is normal,
    I use 80w-90, and you might want to get a flex neck funnel
    and doesn't hurt to check your ring an pinion teeth!
    while your at it check the Tcase!
    as far as additive, I didn't use any and I have Gov-loc
    and no problems But I don't think its required!

    If it ain't Intimidating / It ain't a Chevy!
     
  3. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    I used some RTV on the cover gasket as well(not sure which color though). I've read that if your gasket is still in good shape, you don't even need to replace it, just goop it up with a bit of RTV and bolt it back up.

    Regarding the additive, some gear oil is already formulated for use with a limited-slip diff. It should say somewhere on the bottle if it is.............

    <font color=red>PHOTO ALBUM-</font color=red> <A target="_blank" HREF=http://albums.photopoint.com/j/AlbumList?u=1289798>http://albums.photopoint.com/j/AlbumList?u=1289798</A>.......<font color=blue>TRUCK & HIKING PICS</font color=blue>
     
  4. ftn96

    ftn96 1/2 ton status

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    Thats it DOG!

    Will work for beer, parts and tools.
    90 Jimmy 350TBI-700R4-241-33" BFGs-10 bolts w/4.10's
    <A target="_blank" HREF=http://www.nashvillek5.freeservers.com>http://www.nashvillek5.freeservers.com</A>
     
  5. BlazerGuy

    BlazerGuy 3/4 ton status

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    I have a gov-lock and when I changed my fluid I didn't put any additive in it. Ran it like that for about 2 months and put in some posi additive from the dealer and didn't notice any difference

    Murphy's Laws on Life :
    "It is a mistake to allow any mechanical object to realize you are in a hurry."
     
  6. 77K5Blazer

    77K5Blazer 1/2 ton status

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    How might I go about finding out if I have a gov-loc in my 12-bolt? What exactly is it? Can I get some info and boackground history on it?

    1977 Blazer w/ 350 GM crate motor
    44 front/ 12-bolt rear, gear driven NP205
    31x10.50r15 BFG All-terrain- Larger on the way!
     
  7. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Looks fine to me too but I thought I would throw in a few things. Like someone else said, do a visual inspection of the old oil and the diff (look at gears (rotate) for chips and look in the bottom of the diff and drain bowl for sediment). When putting it back together, I would definitely use some sort of gasket sealer. Also, be careful not to over-tighten the bolts since this can distort the cover and cause it to leak. Follow the tightening pattern (if you can find one, alternate sides otherwise) and do not try to tighten each bolt all at once. I usually "follow the pattern" 3 or 4 times minimum before achieving the final torque rating. If the cover has been previously over-tightened you will probably need to use one of the forma-gasket sealers since it will be very hard to straighten. One other thing, I prefer to slip a rubber hose on the bottle snout rather than use a funnel. Much easier to deal with.

    Bad Dog

    85 K30 CUCV, 350 TBI, TH400, NP205, D60/C14, 4.56
    Coming soon: 4" lift, 40" tires, massive cutting, shorter wb and rear overhang.
     
  8. Sax Art

    Sax Art Registered Member

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    As far as the RVT sealant goes........I used to use the blue type (original) until somebody pointed out that the red (Hi-temp) stuff costs the same and will protect the seal should things ever get too hot. (Of course if the diff. gets hot enough to melt the "blue stuff", I'm guessing the gasket will be the least of your worries!)

    Just a thought anyway.....

    Oh, and I second the comment about using a small piece of hose attached to the top of the container. Or you could use an old (clean!) bottle from dishwashing liquid. (The kind that has the pull top and you squeeze it to get the soap out!) Just fill it with gear lube and you never have to worry about losing a drop!
     

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