Rear main seal faulty after 6 hrs?

Discussion in 'Gas Engines' started by 7228sedan, Oct 2, 2018.

  1. 7228sedan
    Joined: Nov 2009
    Posts: 320
    Likes: 7, Points: 18, Legacy Rep: 60
    Location: New Jersey USA

    7228sedan Senior Member

    Long story short, I installed a re-man long block this summer Mark IV 454.
    The boat went in the water 2nd week of August. I followed all of the typical break in procedures for a fresh build flat tappet cam just prior to the launch.

    After she went in, I put 5 hours on it or so prior to opening it up for a short burst. After the carb issue was worked out, I got it up to 4400 RPM at WOT for a few minutes to make sure she wouldn't blow up :). 21 knots, the best the old girl ever ran.
    Upon getting back to the dock I notice a small puddle of oil in the bilge. The seam between the block and the bell housing is weeping oil. I removed the rubber access cap to inspect the flywheel and coupling. everything is wet with oil.

    As this is a 2 piece rear main, the pan and main cap need to come off to replace.
    Has anyone ever had this happen on a motor this young?
     
  2. Lepke
    Joined: Sep 2015
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    Location: Oregon to Alaska

    Lepke Junior Member

    I've seen it on new and rebuilt engines. Not any I've done. It depends on the guy installing the seal. I grease the journal where the seal rubs so it doesn't get hot before the oil shows up. Both rope and modern seals. If the block was done with cheap labor in some discount rebuild factory...
     
  3. 7228sedan
    Joined: Nov 2009
    Posts: 320
    Likes: 7, Points: 18, Legacy Rep: 60
    Location: New Jersey USA

    7228sedan Senior Member

    I just had her hauled this week... I'll pull the motor after the holidays and take a look. Going to change the oil pan seal and the rear main to rule both out.
     
  4. missinginaction
    Joined: Aug 2007
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    Location: New York

    missinginaction Senior Member

    Don't forget to let us know how this works out 7228. I'm considering an engine rebuild or long block replacement. Any advice you have after you troubleshoot this would be appreciated. Hope it all works out.
     
  5. 7228sedan
    Joined: Nov 2009
    Posts: 320
    Likes: 7, Points: 18, Legacy Rep: 60
    Location: New Jersey USA

    7228sedan Senior Member

    Oh I won't... once I can get the yard to haul the boat into their shop I'll be pulling the motor back out. As I can't confirm if it truly is the rear main or the oil pan, I'll be replacing both. I don't want to do this a 3rd time :)
     
    Last edited: Jan 3, 2019
  6. 7228sedan
    Joined: Nov 2009
    Posts: 320
    Likes: 7, Points: 18, Legacy Rep: 60
    Location: New Jersey USA

    7228sedan Senior Member

    So I finally got the motor pulled and the pan dropped, cap removed etc. Here's what I found, no wonder it was leaking... I polished it up in place with some oiled 1,000 grit and an old belt. Here's to not pulling this motor for a second time!
     

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  7. baeckmo
    Joined: Jun 2009
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    Location: Sweden

    baeckmo Hydrodynamics

    Oops, thanx for sharing!
     
  8. missinginaction
    Joined: Aug 2007
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    Location: New York

    missinginaction Senior Member

    Thanks for updating this 7728. How the heck did that get so rusty though? I'm sure you would have noticed it but I'm not sure if you did the seal personally. I've never had a problem with a leaky rear main but I've always worried about it. Thanks for sharing. MIA
     

  9. 7228sedan
    Joined: Nov 2009
    Posts: 320
    Likes: 7, Points: 18, Legacy Rep: 60
    Location: New Jersey USA

    7228sedan Senior Member

    I purchased this long block assembled with the seal in place...
    It appeared almost as though it was never machined. Either that or the assembled motor was sitting prior to my buying it where moisture got in there... The motor had no pan installed when I got it, I assumed that there would have been other indications of moisture elsewhere if it was a moisture/storage issue...

    That's what I get for saving a buck and buying on ebay... oh well, live and learn.
     
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