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6.2 compression???

Discussion in '1982-Present GM Diesel' started by steve_kibbe, Sep 14, 2004.

  1. steve_kibbe

    steve_kibbe 1/2 ton status

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    What should the compression for a 6.2 diesel be??
    I was going to repalce the injector pump, but wanted
    to check cylinder pressure first. I have the tool, but
    haven't doen it yet.

    Thanks
    Steve
     
  2. alec78

    alec78 1/2 ton status

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    IIRC all cylinders should be within 10% of each other.

    Also, Make sure that the tester you have is for a diesel!!!
     
  3. bigblock454

    bigblock454 Clack Clack Clack Premium Member

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    A new engine can show over 400 PSI, the lower limit per GM is 300 PSI i think.
     
  4. steve_kibbe

    steve_kibbe 1/2 ton status

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    I am testing it cold, It doesn't look to good. Getting
    readings between 60 and 240 psi. I'm going to try to reckeck with some oil in the cylinders. Blown head gasket? Bent rod?
    Any sugestions?
    Thanks
    Steve
     
  5. arveetek

    arveetek 1/2 ton status

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    Don't put any oil in the cylinders! It's not safe to do that on a diesel. They don't call them "oil-burners" for nothing!

    There is a very remote chance that the engine could fire if you squirt oil down in the cylinder. It's not very likely on a cold engine, but it is still possible. If that happens, you could damage the engine and/or damage your guage.

    Also, there is very little space between the pistons and heads. If you squirt too much oil in there, you could hydraulic-lock the engine.

    It's a safe, common practice to do this on gassers, but I wouldn't do it with a diesel.

    Casey
     
  6. steve_kibbe

    steve_kibbe 1/2 ton status

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    thanks for the tips, I do have all the glow plugs out, will it still fire?
    just thought the oil would help the rings.
    Thanks
    Steve
     
  7. AgDieseler

    AgDieseler Certified Scrap Producer Premium Member GMOTM Winner

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    With the glowplug hole open and the combustion chamber exposed, you will not be able to build enough compression to ignite the diesel.
     
  8. bigblock454

    bigblock454 Clack Clack Clack Premium Member

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    List all 8 cylinders and their value. How long has the engine set before you go it?
     
  9. Diesel Dan

    Diesel Dan 1/2 ton status

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    My '91 GM manual states they should not be below 380psi. We had a 6.2 that was in the 310-320 range and didn't start worth diddly when cold.
     
  10. steve_kibbe

    steve_kibbe 1/2 ton status

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    before it sucked water, it did start hard when cold, I will re-check the cylinder pressure tomorrow and list them. I know the 2-8 side was alot lower than the 1-7. I believe #4 was 60psi, and #3 was 240psi. I will list them all.
    Thanks for y'alls help.
    Steve /forums/images/graemlins/thumb.gif
     
  11. imiceman44

    imiceman44 1 ton status

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    [ QUOTE ]
    before it sucked water, it did start hard when cold, I will re-check the cylinder pressure tomorrow and list them. I know the 2-8 side was alot lower than the 1-7. I believe #4 was 60psi, and #3 was 240psi. I will list them all.
    Thanks for y'alls help.
    Steve /forums/images/graemlins/thumb.gif

    [/ QUOTE ]

    I would assume you have bad heads but could also be rings.
    If you have these low numbers it's no good.
    Mine had consistently 230-240 in all 8 and still doesn't start.
    300 I think is reasonably the lowest you want.
     

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