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Chevy 350 1-piece Rear main seal R&R

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by jberg62, Mar 19, 2003.

  1. jberg62

    jberg62 1/2 ton status

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    Hi all,
    I've never done this before but I figured while the Tranny was out (being swapped) I'd like to take care of the leaking one-piece rear main seal.
    If some kind person would please give me a short block of instruction on what to do to accomplish this task I'd really appreciate it.
    I've heard a lot of folks say that it's really no big deal, but I guess they had someone to show them how it was done for their first time.
    Anyhow, I'd appreciate a tip or two...or the whole procedure /forums/images/graemlins/wink.gif
    Thanks a bunch!
    Jim
     
  2. fortcollinsram

    fortcollinsram 1/2 ton status

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    Well first and foremost, you must remove the transmisson/ t-case and the clutch/ Torque converter from the engine next, you must remove the flywheel/flexplate to expose the rear main...on the 350, the seal is in its own aluminum adapter that bolts to the block.

    Next you need to remove the rear main...this can be done two ways...you can either remove the seal from the adpater while the adapter is still bolted to the block by prying it out with a screwdriver or similar device. I used the alternate method of removing the adpater for the block and THEN prying the seal out of the adapter...once the old seal is out, clean the adapter and the block mating surface and press the new seal into the adapter...I simply used a piece of 2x4 to push the seal in...When you place the adpater back on the block you must replace the paper gasket on the upper half of the adapter... then simply bolt the adapter back on the block, making sure not to nick the seal on the crank as you slide it on...

    I can not recall if the oil pan needs to be removed to complete this operation...

    I replace mine when I was swaping my tranny so it was a perfect time /forums/images/graemlins/thumb.gif good luck..

    Chris
     
  3. milspecjimmy

    milspecjimmy 1/2 ton status

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    step # 1, take a screw driver and pry out the old one using the three notches in the aluminum housing. step #2 take the new seal and pack some heavy grease in the back of it filling the groove completely. this will keep the spring from popping off when you install it(if you dont get a teflon seal, wich has no spring). then grease the end of the crank shaft(so it will slide on and not tear) then push the seal gentaly onto the crank shaft, you'll have to work it on, youll see what i mean when you get to that point. youll have to push up on it and slowly work it on, then just push it onto the shaft and take a large socket or some thing solid and pound it into the retainer as evenly as possible.
     
  4. jberg62

    jberg62 1/2 ton status

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    Wow, thanks very much guys for those speedy and informative replies. I guess it really isn't that difficult to do after all. I'll be attempting to R&R it over the weekend.
    As far as Grese goes, I understand that some on the Crankshaft will ease in the seal installation but should I also put some on the outside of the seal or does that go into the adapter dry?
    If I decided to do it by removing the adapter from the block could I get another paper gasket from pep boys or someplace like that or would I have to make my own gasket outa something?
    Thanks again gentlemen /forums/images/graemlins/thumb.gif
     
  5. fortcollinsram

    fortcollinsram 1/2 ton status

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    When I bought my Fel-Pro gasket from Jegs, it had the paper gasket in the kit as well...You don't have to put grease on the OD of the seal when you put it in the adapter, but it won't hurt anything...These seal most always leak at the crank/seal surface..It really is pretty easy...in a Gen V and VI BBC, you don't even have the adapter, the seal just presses into the rear main cap...



    Chris
     
  6. loudnowlouder

    loudnowlouder 1/2 ton status

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    [ QUOTE ]
    I can not recall if the oil pan needs to be removed to complete this operation...

    [/ QUOTE ]

    nope doesnt need to be removed, the old style did, that was a big pita job, but the one piece isnt too bad at all
     
  7. R72K5

    R72K5 Banned

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    yeah oil pan has to be tremoved for doing two piece seals not one piecers, make sure you have a one piece for sure before you start, 86 and up are one piece, 79 and older are two, two piece are alot easier to do because you dont have to remove tranny.

    good luck
     
  8. 84_Chevy_K10

    84_Chevy_K10 Banned

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    [ QUOTE ]
    86 and up are one piece, 79 and older are two, two piece are alot easier to do because you dont have to remove tranny.

    [/ QUOTE ]

    55-85 are two piece
    Most 86 are 1 piece, but I've seen 2 piece 86s as well
    87-present are all 1 piece
     
  9. jberg62

    jberg62 1/2 ton status

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    Well, I finally got a chance today (after removing the transmission and Transfer Case) to have a face to face with my Chevy's rear main seal.
    I fought for about 10 minutes with the Flywheel, but it yielded to my cursing and a little PB Blaster /forums/images/graemlins/wink.gif
    The Rear Main Seal (1-piece) actually looks fine and the oil that is leaking is more than likely coming from the rear of the oil pain.
    I've purchased a 1-piece rubber oil pan gasket and will install that tomorrow and return the RMS on Monday.
    It did look mega-easy to do though.
    Thanks everyone for your help with this.
     
  10. R72K5

    R72K5 Banned

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    [ QUOTE ]
    [ QUOTE ]
    86 and up are one piece, 79 and older are two, two piece are alot easier to do because you dont have to remove tranny.

    [/ QUOTE ]

    55-85 are two piece
    Most 86 are 1 piece, but I've seen 2 piece 86s as well
    87-present are all 1 piece

    [/ QUOTE ]

    i have yet to see a two piece 86 engine, if you run into a nother two piece 86 then i want the casting date code off the top rear and also suffix code stamping off the front pad

    good luck
     

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