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Technical HEAD GASKET LEAKING STRAIGHT 8

Discussion in 'The Hokey Ass Message Board' started by bgreene30, Jan 14, 2017.

  1. bgreene30
    Joined: Feb 26, 2011
    Posts: 44

    bgreene30
    Member

    Hello All, Had a really bad day today. Finally ready to fire up the 48 Pontiac Streamliner with completely rebuilt original straight 8 and we noticed anti freeze dripping on the back of the block at he bottom off the boss.

    Come to look a little more and pre mixed anti freeze is dripping from between the head and block at the back above the freeze plug.

    I have been told the L8 heads were prone to that due to the length. I do not know if that is true. what i do know is it had a blown head gasket and sat for 30 years. Our machinist has never let us down so just curious what the group recommends? If it matters rebuild had to go 60 over, heads torqued per manual to 60 ft lb, rechecked after leak detected. We primed oil system by turning starter over with all spark plugs removed. BTW- is there are better/safer way to do this?

    We are planning to pull the head, look at the gasket and take the head back to the machinist.

    Cheers,
    Bob
    So Cal
     
  2. Vimtage Iron
    Joined: Feb 28, 2010
    Posts: 561

    Vimtage Iron
    Member

    You may want to pull the studs and use the Perma tex teflon or the GM sealer on them,if they are in the water jacket, that could be one problem, the head my not be flat, did you coat the gasket with copper coat, and I've used Iron Tite in the system when putting these back together and have had very good luck.
     
  3. You say the machinist is a good guy.
    You also say the engine received a "complete rebuild" .
    (1) What was done to the cylinder head or the deck of the block ?
    (2) WHO did the re-assembly of the engine ?
     
  4. some times those long blocks sag
    was the block decked?
     
  5. bgreene30
    Joined: Feb 26, 2011
    Posts: 44

    bgreene30
    Member

    both were surfaced, mated and flat.
    My machinist.
     
  6. bgreene30
    Joined: Feb 26, 2011
    Posts: 44

    bgreene30
    Member

    yes the block was decked
     
  7. bgreene30
    Joined: Feb 26, 2011
    Posts: 44

    bgreene30
    Member

    Hi, we pressurized the system and she leaks and pisses all the way around. We are going to order a new head gasket or two and when they arrive pull the head and have a look at the block, head and gasket. Also going to make sure the locating pins are going all the way down.

    Stay tuned!
     

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