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Rear main seal.

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by BlazinRojo, Aug 30, 2001.

  1. BlazinRojo

    BlazinRojo 1/2 ton status

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    Alright, my 83 350's rear main seal is leaking. I should be able to just drop the oil pan and replace since its a two piece seal (I know its more complicated than that), but I've heard that its almost impossible to get a new rear main in without it leaking again. Is it worth it? Or should I just wait until I scrounge up enough for a new edelbrock crate engine and live with the drip?

    Shutup Brain or I'll stab you with a Q-Tip - Homer J. Simpson
     
  2. txbartman

    txbartman 1/2 ton status

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    If it ain't dripping too bad, I'd just live with it.

    But just my 2 pennies.

    Brian
    Click to see <a target="_blank" href=http://tx85gmcguy.alloffroad.com> My 85 Jimmy </a>
    Who put a stop payment on my reality check?!?
     
  3. blazbrnc

    blazbrnc 1/2 ton status

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    I changed one on an '86 350 and it wasn't too bad. After pulling the pan, remove rear main cap (oil pump also). Loosen the next cap forward a few turns and the one before that a few less turns. Use a small screwdriver to push one end of the seal so the other end becomes visible. Take some needle nose pliers and pull it out. Be carfull not to nick the bearing journal on the crank. Slide the new half in, put some silicone on the ends of it and install the cap, retorque caps, install pump and pan and your done. Oh yeah, you may have to loosen some of the lower timing chain cover bolts to remove and install the pan. If you stay away from the muddy watery holes it shouldn't leak anymore. I have found that rear mains typically leak when exposed to muddy water because the dirt gets trapped in between the two lips on the seal and kinda chews up the crank a little. A new seal should last a while though.

    '79 K5, '79 Suburban, '76 Br**co, 77 K20
    '99 BB 4x4 Suburban to tow more junk home
     
  4. Stoopalini

    Stoopalini 1/2 ton status

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    huh, this is pretty interesting to me. I thought I would have to drop the transmission to change my rear main. It's been leaking for a while now (not too bad) and I was dreading the job; but if I can do it just by getting into the pan, that's great!

    Thomas.

    -- '84 K5 Blazer --
    <a target="_blank" href=http://stoopalini.off-road.ws/blazer>My Blazer Site</a>
     
  5. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Only '86 and later engines would you have to drop the tranny to change it.

    I'd do it. It's cheap and easy.

    Tim
    '84 Chevy K10, lifted, loud, fast, and 3/4 ton axles
     
  6. muddin4fun

    muddin4fun 3/4 ton status

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    If it's leaking like a siv, then change it. But small block chevys had a problem with the rear main leaking. You won't be able to get it to stay completely dry.

    It's been lovely, but I have to scream now.

    <a target="_blank" href=http://www.geocities.com/muddin4fun79blazer>My wonderful site</a>
     
  7. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Mine doesn't leak a drop.

    Tim
    '84 Chevy K10, lifted, loud, fast, and 3/4 ton axles
     
  8. Stoopalini

    Stoopalini 1/2 ton status

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    I'm getting ready to pull my pan, and had a quick question about changing the rear main.

    The replacement seal has 2 halfs; do I just replace one half of it? When I drop the pan, will I be able to replace both halfs?

    Thanks,

    Thomas.

    -- '84 K5 Blazer --
    <a target="_blank" href=http://stoopalini.off-road.ws/blazer>My Blazer Site</a>
     
  9. Beast  Owner

    Beast Owner Registered Member

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    When you take off the oil pan, take off the oil pump then remove the 2 bolts from the "end bearing cap". Take the cap off...........(some times you may have to tap it on the side with a rubber mallet. Take seal out of bearing cap, then tap lightly with small straight screwdriver, the top half of the bearing over the crank journal. Once it moves a little pull it out with pliers!! Be careful not to nick the journal. Lube the slots on the new halfs and install then seal the ends with a little RTV. IMPORTANT&gt;&gt;&gt;&gt;&gt;&gt;&gt;MAKE SURE THE LIPS PROPER EDGE IS FACING TOWARD THE FRONT OF THE ENGINE ON BOTH SEALS!!!! see enclosed instuctions. Torque main cap bolts at 80 ft lbs. re assemble............
     
  10. Beast  Owner

    Beast Owner Registered Member

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    sorry not the top half of the bearing................but the top half of the seal!!!!
     
  11. Highlander

    Highlander 1/2 ton status

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    Hey Stoop
    You should replace both seals. And I was Always told not to line up the seal ends with the main bearing cap but to offset the seal just a little. Eric

    <a target="_blank" href=http://cethern.tripod.com/erics-home-page-and-other-stuff/>http://cethern.tripod.com/erics-home-page-and-other-stuff/</a>
    AMSOIL Dealer # 529948
    Cethern@interfold.com
     
  12. Stoopalini

    Stoopalini 1/2 ton status

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    Alrighty then, thanks guys.

    I just finished removing the pan and came in to check for any replies. Back out I go to get that rear main out....

    Thanks guys, I appreciate it!

    Thomas.

    -- '84 K5 Blazer --
    <a target="_blank" href=http://stoopalini.off-road.ws/blazer>My Blazer Site</a>
     
  13. Blazer79

    Blazer79 1/2 ton status

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    Does anybody know if this is the same procedure for my 1979 454? I know the torque specs are different and I already ordered the seal kit for mine, but the fact of loosening and retorqueing the main caps scares me. Any do's and dont's?

    Thank you.

    <font color=purple>//////
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    Soon a 454 K5!!</font color=black>
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  14. Stoopalini

    Stoopalini 1/2 ton status

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    One more question guys,

    When I removed the pan, there was silicone all around the cork seal and on the rubber end seals. Should I put silicone on the new seal? I've always just used the cork and rubber seals and never silicone, but maybe this is different??

    Thomas.

    -- '84 K5 Blazer --
    <a target="_blank" href=http://stoopalini.off-road.ws/blazer>My Blazer Site</a>
     
  15. CaptCrunch

    CaptCrunch 1/2 ton status

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    There is a tool called the Sneaky Pete tool that is really cheap and will grab the seal and put the top back in without risk of damaging the new seal or journal. Highlander is right offset the place where the seals meet compared w/ the caps.

    STOOPALINI: Don't use any RTV on the cork portion of the gasket. If you have a cork gasket on there now w/ rtv it may be the gasket itself leaking because rtv generally causes the cork to crack. You can use rtv on the rubber ends, just keep it away from the cork. My extra $.02 is call up Jeg's or Summit and get one of those one piece oil pan gaskets. It will make it 200 times easier on you back when you are trying to position the pan over the pickup. Also make sure you do not mess up the oil pump pickup if it is not welded already. It would be wise to make sure it is position just off the bottom of the pan before you button everything back up.

    -Mikey
    1987 Chevy K5 Blazer- 350 TBI
    <a target="_blank" href=http://coloradok5.com/gallery/captcrunch>http://coloradok5.com/gallery/captcrunch</a>
     
  16. CaptCrunch

    CaptCrunch 1/2 ton status

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    What is your 454 from Blazer79? Chances are is is a Mark IV block (1970-90) which has a 2 pc. seal. The Gen V(91 and up) and Gen IV (96 and up) which also includes most of the GM performance Blocks and crates are a one piece seal.

    Just make the bottom part of the bearing doesn't get put in the wrong way or get dirty and see my note above about gaskets and the pickup. I also usually wipe on some fresh 30 wt oil on the bearing before I put it back up and like on any oil change on my trucks or cars I fill the oil filter full of oil before I screw it on (if it is a vertical jobber) to cut down the time it will take to get oil to the pump. It's a messy job on your back sometimes, but not too hard to accomplish. The last one was on an IFS truck which required me to remove/relocate the front axle so it could be worse. Even that wasn't too bad. Good Luck everyone!

    -Mikey
    1987 Chevy K5 Blazer- 350 TBI
    <a target="_blank" href=http://coloradok5.com/gallery/captcrunch>http://coloradok5.com/gallery/captcrunch</a>
     
  17. Stoopalini

    Stoopalini 1/2 ton status

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    I ended up putting a very small amount of RTV on the top of the cork seal, so it would stick top the bottom of the engine while I lifted/bolted the pan into place. I did not put any in between the pan and the gasket; just between the gasket and the block.

    This made it a lot easier to line it up and have it stay there while I manuvered the pan into place.

    On a side not: I am constantly reminded how easy these trucks are to work on! I've never replaced a rear main so easily [​IMG] thanks for everyone's help, I truly appreciate your willingness!!

    Thomas.

    -- '84 K5 Blazer --
    <a target="_blank" href=http://stoopalini.off-road.ws/blazer>My Blazer Site</a>
     
  18. Blazer79

    Blazer79 1/2 ton status

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    Thanks Capt Crunch.

    It's a Mark IV (1979) that came from a dually tow-truck, so that makes it a two piece seal. This is the last item I need to go through to be able to install the engine.

    I'll be very careful and follow your directions in detail, lets see how it goes. The order I placed should arrive on next week's wed or thur. I'll let you know how it goes.

    Thanks [​IMG]

    <font color=purple>//////
    <a target="_blank" href=http://blazer79.freeyellow.com>blazer79.freeyellow.com</a></font color=purple><font color=black>
    Soon a 454 K5!!</font color=black>
    [​IMG]
     

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