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Differential Cover Leak!

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Peeetah, Jan 3, 2001.

  1. Peeetah

    Peeetah Registered Member

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    I looking for some opinions on how to stop a leak in my rear end cover. I have tried to reseal this thing twice and it seems to be the same story each time. It works at first but three months later it develops a leak at the bottom. I've heard so many different opinions on the proper way to seal it. I just purchased a new cover and cork gasket. I would appreciate any insight into what to use to along the line of RTV with a cork gasket. In additions the torque specs for the bolts. I have a GM truck 12 bolt.
     
  2. Stoopalini

    Stoopalini 1/2 ton status

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    If your Diff cover is damaged, it will leak. After you replace the Diff cover, make SURE you check your vent. Verify that it is not clogged up and also that the hose is not plugged. If the diff is not venting properly, it will develop a leak over time.

    It sounds like either your Diff cover is bad, or your vent is clogged.

    There is no secret to sealing them up. I don't even use a cork gasket ..... I have always used Blue RTV, and only Blue RTV, to seal my Diff covers.

    Good luck,

    Thomas.

    -- '84 K5 Blazer --
    <A target="_blank" HREF=http://Stoopalini.coloradok5.com>http://Stoopalini.coloradok5.com</A>
     
  3. HarryH3

    HarryH3 1 ton status Author

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    Is the cover bent? Check it with a straight edge. Also take a look at the area around each bolt. This can get dimpled to the point that the cover doesn't seal properly. A bit of work with a small ball pein hammer can fix this. As for gaskets, like Stoopalini, I don't use one. Just a nice bead of RTV. Never had a leak.

    <font color=black>HarryH3 - '75 K5</font color=black>
    <A target="_blank" HREF=http://ThunderTruck.ColoradoK5.com>http://ThunderTruck.ColoradoK5.com</A>
     
  4. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Also make sure the gasket surface on the diff housing is completely clean of gear oil. I use brake cleaner. I also just use RTV and it never leaks.

    Rene

    [​IMG]
     
  5. Burt4x4

    Burt4x4 3/4 ton status

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    I never use any type of gasket.
    I use black RTV.
    Black= oil
    Blue= water
    Red= High Temp(exhaust)
    Clear= rubber gasket stuff (window/weather)

    First I run a small bead on the diff cover then I run a small bead on the housing. I let it sit for 20 min or two beers to allow the RTV to set, then bolt it up in a criss cross patern.
    I have never had a leak by doing it this way.
    As said make sure your breather is breathing!!

    72K5[​IMG]Led Zeppelin[​IMG]Rock ON![​IMG]
    <A target="_blank" HREF=http://www.burt4x4.coloradok5.com>http://www.burt4x4.coloradok5.com</A>
     
  6. mudhog

    mudhog THEGAME Staff Member Super Moderator

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    very good point if you keep having leaks check the vent tube also never use cork always ask 4 felpro gaskets

    s.smith 77blazer lookin 4 mud
     
  7. Channing74

    Channing74 Registered Member

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    I agree with mudhog ..... if your gonna use a gasket use felpro ..... no silicone ....... but if you want to seal with silicone my personal favorite is made by victor part # JV6 Gray in color ........ Made for GM to use in factory.

    Bigger is Better [​IMG]
    Channing74
     
  8. Peeetah

    Peeetah Registered Member

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    Thanks for all the posts! Still have few more questions. Since I am indeed going to use a cork gasket what should I put on it if anything (weatherstripping snot, RTV, Other?) Also where is this vent tube and how do I check if it is indeed clogged? Once again thanks for all the earlier replys.
     
  9. Stoopalini

    Stoopalini 1/2 ton status

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    I would not recommend using the cork gasket at all. If you do use it though, don't put any goop on it at all ........ use just the gasket and a torque wrench. Torque the bolts to the recommended spec.

    Go to this link:
    http://Stoopalini.coloradok5.com
     
  10. Blue85

    Blue85 Troll Premium Member

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    One more thing: Even if the surface on the diff is clean, if there is oil and crud in the bolt holes, it will squish up onto the (formerly clean) sealing surface when you put the bolts in. Just spray the bolt holes out with brake cleaner, especially the ones near the bottom, since they always fill with oil as it drains.

    "Big? No, these tires might be big for your Jeep, but they're just temporary for my K-5" [​IMG]
     
  11. BigJim85

    BigJim85 1/2 ton status

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    I have a different kinda leak. I keep getting water in my diff and it concerns me. First time I noticed it was after a camping trip and some BIG puddles of water, there was what looked like malt milkshake dripping out of it. Drained it, new gasket, and torqued it down and when I checked it this weekend it looked just like a malt milkshake. I have no idea about it this time, I havn't been in water at all for a month (aside from rain and snow) and, quite frankly, I'm baffled. Any help is appreciated.

    <font color=red>If it's stupid but works, it isn't stupid.</font color=red>
    [​IMG]
     
  12. HarryH3

    HarryH3 1 ton status Author

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    Did you thoroughly clean out the case when you changed the fluid last time? If there was water in there, then the mixture can go all through the housing, out to the axle bearings at the wheel. You may just be seeing more of the old goo getting mixed with your good oil. Sounds like it may be time to pull the diff cover, pull the axles and clean out the entire housing. Then refill it with fresh lube. [​IMG]

    <font color=black>HarryH3 - '75 K5</font color=black>
    <A target="_blank" HREF=http://ThunderTruck.ColoradoK5.com>http://ThunderTruck.ColoradoK5.com</A>
     
  13. Stoopalini

    Stoopalini 1/2 ton status

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    Sounds like either your vent hose is gone and water is getting in the vent hole ........... or maybe one of your seals are toast. (pinion seal and 2 axle seals). If one of the seals is bad, water will drip in through it.

    I wuold check the vent hose 1st though, it's most likely your problem.

    Thomas.

    -- '84 K5 Blazer --
    <A target="_blank" HREF=http://Stoopalini.coloradok5.com>http://Stoopalini.coloradok5.com</A>
     
  14. BigJim85

    BigJim85 1/2 ton status

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    Thanks guys, I'll check 'em out.

    <font color=red>If it's stupid but works, it isn't stupid.</font color=red>
    [​IMG]
     
  15. bennett

    bennett Registered Member

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    A freind of mine is a mechanic at a ford dealership and sets up all rear end work. He says black RTV is good but for the best he uses Permatex "The Rright Stuff". I personally put it to the test on a Landcrusier(76) transfer case ...It leaked everywhere. I use the "right stuff" its got great hold and will allow for imperfection between two mated peices and still seal. I can attest to the fact that after 2000 miles of hard driving , I had one leak ( at the speedo) a small drip, I took off the speedo collar and spread the "right stuff " in and presto. No leaks . Do a search on the web under "permatex" and "right stuff" and read up on it. I was a non believer but the way this stuff comes out and goes on and seal will amaze you. You can get it at any auto parts store. Can you tell I believe in it? no I dont own stock in permatex.... give it a try and PS my freind does not use gaskets when putting diff covers back on, just this product. Call backs cost money and this has eliminated tons of call backs for drippy drivetrain leaks on clean driveways.
     
  16. K5 NUTT

    K5 NUTT 1/2 ton status

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    Had the same problem except mine leaked every darn time i went rockin out here from banging it on rocks. So this time i went down to GM and bought a new one....and sealed it with the same stuff Rockwell gives us to seal big truck diffs...Ultra Gray...about 4 to 5 bux at the local napa store ...or $25 bux if you buy it from a class 8 truck dealership with Rockwell's sticker on the package....lol. Anyways i changed it out 3 weeks ago and it hasn't leaked yet!

    Azblazer

    1979 K5
    1976 K5 Chalet
    1972 K10 Suburban
     

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