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rearend keeps leaking!!!!!!

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 90K5, Oct 23, 2001.

  1. 90K5

    90K5 1/2 ton status

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    Everytime I go to my truck, there are a few drops of gear oil under the diff. I've already changed the fluid in that thing like 5 times since it got rebuilt, but it leaks everytime. I used RTV the first couple times, then I went and bought a gasket for it yesterday. Today it leaks again. the cover seems flat, so it shouldn't leak. The gasket is just a Fel-pro paper one, and I put some gasket stuff (not RTV) on both sides of it yesterday. Do I need to put RTV on it? I'm getting really sick of doing this. Its getting expensive too. 3qts of Valvoline Dura Blend at $5 each and a $7.50 bottle of LSD additive...grrrrrrr

    90K5
     
  2. Burbinator

    Burbinator 1/2 ton status

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    Try scuffing the mating surfaces with a fine sandpaper to give the gasket/sealant something to "grab" onto.

    The learning curve is a toll road...ride with someone who has already paid!
    <a target="_blank" href=http://photos.yahoo.com/abshort1>My Naval Fleet</a>
     
  3. ftn96

    ftn96 1/2 ton status

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    Also, are you SURE its coming from the cover and not the pinion seal? As oil leaks from the pinion seal, it tends to run down the bottom of the pumpkin and drip from around the bottom of the cover. Just a thought.
    Whip the entire outside of this thing down the night before and see if you can tell where its leaking from. If its still the cover try and trace the flow of the leak back to its origin and then when you take the cover off, maybe you can see if there is anything obvious in that area that may appear to casue a leak.

    Surgeon General's Warning:
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  4. dyeager535

    dyeager535 1 ton status Premium Member

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    I went through this before as well. First off, you sure its the diff cover and not the pinion seal? Of course that will leave a tell tale streak down the underside from there...

    How about the bolts? Are the bolts staying tight or loosening up? PO on mine had used bolts that were too short, and they ALL backed out after less than 100 miles. The correct, longer bolts solved the problem.

    There are way too many different ways to seal gasket surfaces for any one to be right for all instances. What works for one, won't work for another. You can use no gasket, silicone only. You can use no silicone, gasket only. You can use silicone with gasket. Etc.

    What I do, on valve covers, oil pans, and diff covers, is to use a VERY thin layer of RTV (Usually black in my case, because its what I typically have) on the pan/cover side ONLY.

    Clean the diff surface up with paint thinner and some paper towels Check the surface for any raised edges, such as where the diff hit a rock, and pushed up a little corner, or where a screwdriver put a nice scratch. File any abnormalities down. Park backwards on a hill (if rear diff) so that when you drain it, the left over fluid doesn't keep dribbling down the gasket surface..scoop some of the remaining sludge out just to insure that it doesn't interfere with sealing.

    Clean the diff cover off with thinner as well. Lay it flat on a known flat surface, like a table. See if it "rocks", since a flat cover will sit perfectly flat. If you can see light under it, then the bolt holes are bulged, and can be LIGHTLY hit with a hammer to smooth them. (don't have to be perfect, thats why theres a gasket)

    Once you've got all that taken care of, I (again, VERY lightly) smear silicone only on the diff cover gasket surface. So thin that in spots you will see metal through it. Go around the bolt holes as well. Then, mate the cover to the diff. Bolt it up. Bolts snug, about as tight as you reasonably can with your hand on the head of the ratchet, not the handle. Not bolt breaking tight. Let it sit for an hour or two (if you really want to make sure not to leak) then refill with fluid.

    If you are getting continuous leaks, I'd be checking the diff cover for "flatness" and probably the housing as well.

    BTW, re-use the diff fluid, just use a clean pan to catch it, especially if it's that new. (or do you mean it leaks that much lol)

    Dorian
    My tech/links page: &lt;a target="_blank" href=http://www.dorianyeager.com/index2.html&gt;www.dorianyeager.com/index2.html&lt;/a&gt;
    Why insist on counting when the ring gear has the tooth counts stamped in?
     
  5. 90K5

    90K5 1/2 ton status

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    Well I just went out there to wipe it off, there was a little oil on the sides, and a very small drop on the ground, so it may be runoff from when I filled it up. Took the fill plug out to fill it up if it needed it, and about 1/2 a quart of fluid came out. This was on my front driveway, which is totally flat. I guess the back driveway is on a little more of a hill than I thought, since thats where I filled it up last night. Now I'm worried aobut the LSD additive...its thinner, so it should be sittign at the bottom right now, right? Or will I have to go buy more of it since some just came out? Hopefully there weren't any leaks though...just runoff.

    90K5<P ID="edit"><FONT class="small">Edited by 90K5 on 10/23/01 02:14 PM.</FONT></P>
     
  6. dyeager535

    dyeager535 1 ton status Premium Member

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    I really like using that Bra-Kleen stuff ($.99 a can on sale) to spray off oil. It dries almost instantly, and removes all trace of oil. You can be sure if its leaking or not if you clean it with that stuff.

    Dorian
    My tech/links page: <a target="_blank" href=http://www.dorianyeager.com/index2.html>www.dorianyeager.com/index2.html</a>
    Why insist on counting when the ring gear has the tooth counts stamped in?
     
  7. ftn96

    ftn96 1/2 ton status

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    I think the additive mixes pretty well with the rest of the diff fluid. So I dont think you have to worry about it sitting at the bottom and it leaking out first.
    Try and get the leak resolved before you by anymore additive. If its your diff cover (at or below) the level of the fluid then it will leak weather you drive it or not.
    So got out there and whip the fill plug off real good, all around the diff, the pinion seal. The whole damn thing. Then go back every so often and check for leakage.
    Then if no leaky by the time you get ready to leave. Just drive it then when you get where you going get out and check it and see where its coming from.

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  8. 90K5

    90K5 1/2 ton status

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    Allright I'm an official idiot. Just thought I sprayed some STP Brake cleaner on it, walking back to the garage, and looked at the can, and it was STP silicone spray...where did my brake cleaner go? Too bad I probably used silicone spray to clean the axle housing yesterday too!!!! It should be OK though, right? Hey silicone is a sealer...seriously though, any way the silicone could mess up the rearend?

    90K5<P ID="edit"><FONT class="small">Edited by 90K5 on 10/23/01 02:46 PM.</FONT></P>
     
  9. TXsizeK5

    TXsizeK5 1/2 ton status

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    How much did you spray in? Also make sure its not leaking from the pinion seal or whateveer and make sure the cover doesnt have a hairline crack... thatswhat happened to me.. i thoguht it was a cover leak and it was from the piniion and a crack in the cover... sucked...

    6in 87' K5 w/ 35" BFG muds.
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  10. dyeager535

    dyeager535 1 ton status Premium Member

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    lol! Silicone prolly won't hurt anything, at least in the quantities you would have used. But with cork (thats what you are using?) you might have some problems. One of the rubber gaskets would love the silicone though, as long as you hadn't used RTV at the same time.

    Dorian
    My tech/links page: <a target="_blank" href=http://www.dorianyeager.com/index2.html>www.dorianyeager.com/index2.html</a>
    Why insist on counting when the ring gear has the tooth counts stamped in?
     
  11. 90K5

    90K5 1/2 ton status

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    I used a paper gasket with gasket spray stuff on both sides, and wiped the mating surfaces down with a rag, so there shouldn't be any silicone near the gasket...

    90K5
     
  12. 90K5

    90K5 1/2 ton status

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    I think I got it to stop leaking...sprayed some brake cleaner - the real stuff - on it and tightened the bolts down a little more. I can feel a little more friction coming from the rear than I would like, so I think I'll have to get some more LSD additive and put an oz. or so in there, maybe top off the oil too.

    90K5
     
  13. yeild2me

    yeild2me 1/2 ton status

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    doesnt the additive make it grip??? meaning that if it has more friction than you like there is too much in there??? not trying to be a smart@ss, just curious because i changed my fluid and only put 7 oz in and it slipped like crazy. when i first put my rear in, i used the premixed stuff that was the right ratio and it worked fine. i bought the second tube to put in it, but havent done it yet......

    350 TBI, 700R-4, NP241, D44-14FF, 4:10's, 38.5 TSL/SX's, full conv., full cage
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  14. 90K5

    90K5 1/2 ton status

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    7 oz. is too much...are you using the GM stuff? If so, all you need is 4oz. I had that much in mine for a little while and it worked great. Its just that some of it leaked out, and some came out when a bunch of fluid poured out later...so I need to add a little

    90K5
     
  15. coopertwpk

    coopertwpk 1/2 ton status

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    Mine had a hairline crack on the inner edge the only way i saw it was when i took it off and sanded it down to repaint it.

    88k5 silverado w4"lift <font color=orange>d44 and corp14ff</font color=orange> with 4.11
     
  16. Blazin Obsession

    Blazin Obsession Registered Member

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    I just went through the same thing,,, I tried everything and the thing still leaked,,,,finally I got a different cover and use the gasket and sealant and all is fine. My first cover looked fine but I believe that it was the problem.
    Good luck
    Ken
     

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