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Thread: ...455 Rear Main Seal Leak...

  1. #1
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    Default ...455 Rear Main Seal Leak...

    ...Hi... ...My '73 Centurion 455 Convertible has a rear main seal leak... ...It has leaked slightly for ten or so years but not enough so that I would have to add oil between changes... ...I havent driven the car in 3 years but prior to this last storage the leak became somewhat worse... ...It's time to fix all the leaks...(turbo 400 also leaks)... ...I was told by a pretty savy guy that just replacing the rope seal might not do the trick...as possibly there may be some excessive clearance in the main bearings???... ...Any guidance I could get from you guys would really be appreciated... ...I am unsure of how many miles are on the engine but I would guess 110K to 140K ???... ...It had the valves done at some point many years ago possibly around 70K... ...The engine runs great and makes no strange noises once the oil pressure is up...
    ...Thanks in advance... ...I should have added that in the 20 years I've owned the car it has had pretty low oil pressure,...20 lbs at idle...
    Last edited by William Bryden; 03-02-2013 at 09:05 PM.
    Willie B

  2. #2
    Join Date
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    Saint Charles, Missouri, United States
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    How much have you driven the car since you realized the leak got much worse? I've found that "exercising" the seals (driving the car) will help seal them back up somewhat. Same with your transmission issue.
    Adam Martin
    BPG# 1358
    BCA# 39765
    1970 Buick Skylark Custom 455 Coupe


  3. #3
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    Quote Originally Posted by Smartin View Post
    How much have you driven the car since you realized the leak got much worse? I've found that "exercising" the seals (driving the car) will help seal them back up somewhat. Same with your transmission issue.
    ...The main seal won't seal up by driving it although the trans will... ...It took me years to actually figure out where the engine oil leak was... ...With the trans in the time it has been stored this time it has leaked 2 to three quarts of fluid... ...It has saturated a couple of bags of kitty litter...
    Willie B

  4. #4
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    Hi William,

    I too have a leakage of engine oil coming from the area between the engine and transmission, but only if the car has the front jacked up or parked uphill.
    I assume its that crescent shaped sealing at the end of the oil pan that needs replacing; I have a pan gasket set laying out in the garage but since it involves lifting the engine a little to get the pan off and I donít have that equipment for that, it never got installed.

    I have tried tightening the pan bolts a little instead but it didnít help
    Per

    Buick Centurion two door hardtop 1973
    Hyundai Santa Fe 2006
    Honda Accord 2009
    Cadillac Seville STS 1999

  5. #5
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    ...Now I am really confused???... ...About a year ago I jacked the front of the car up and let it sit overnight... ...There was oil coming from the small hole in the torque converter dust cover... ...I pulled the dust cover and it appeared that the oil was coming down from the rear main seal and not the pan... ...But that was a year ago and I can't really remember if I stuck a cotton swab up in there or not???... ...In thinking about where the car left the biggest amount of oil,... ...It was definately where the front of the car was on an up hill incline???... ....Hmmmm...grumble grumble???...
    Willie B

  6. #6
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    Ainít troubleshooting great mental acrobatics

    Why didnít I think of the possibility of removing that cover to inspect like you did
    Per

    Buick Centurion two door hardtop 1973
    Hyundai Santa Fe 2006
    Honda Accord 2009
    Cadillac Seville STS 1999

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