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m42 flunked compression test

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    #1

    m42 flunked compression test

    A couple weeks ago I picked up a 91 318is to start to transition my LeMons team into now that our old 325 is starting to actually fall apart. The car was not running due to a missing radiator and AFM and seems to have been sitting for a while.

    So started this weekend by running a compression test. Here are the results:

    215-50-60-55

    I dropped some oil in the 3 low cylinders and the numbers didn't really get better. I'm thinking head gasket or cracked head?

    And some pics:
    Attached Files
    #30 Overengineer'd Racing - Wilton, NH
    We need friends
    Tags: None
    #2
    Could be:
    Bent valves
    Worn rings
    Blown HG
    Possibly some big head cracks, warpage
    Originally posted by Gruelius
    and i do not know what bugg brakes are.

    Comment

      #3
      Wonderful... I'm thinking about putting it together enough to get it running a but, then recheck the compression. It's been a few years maybe some valves are gunked up and open a bit? Can't hurt?

      It needs an ICV and I have a few from m20's hanging around, are they they same or does it have a specific one for the m42?
      #30 Overengineer'd Racing - Wilton, NH
      We need friends

      Comment

        #4
        What's your M20 Lemons car look like? You may be better off swapping the M20/harness over to the new shell.

        I'd hate to run a car in LeMons with as little torque as the M42 has. Plus I'd hate to try and fix an M42 in your pit when it breaks.
        Originally posted by Gruelius
        and i do not know what bugg brakes are.

        Comment

          #5
          some people squirt oil into the cylinders to see if it will help

          there is a oil out there called marvel mystery oil

          I think
          with those numbers, not even a marvel or a mystery oil is gonna help


          ok. jokes aside, I have brought back some real dead rusted cylinders by putting in a bit of atf adn letting sit for a day, slowly rotate to expose new cylinder metal and let it sit again, repeat
          the atf is agressive enough and thin enough to get into small areas

          then with plugs still out, crank with starter motor to shoot out oil, yep messy, but you dont want to try to start it or turn it over under compression wth cylinders full of liquid

          Ive seen some pretty bad numbers come back with the compression ring and oil ring being able to flex again

          is this the best fix, no, is this the right fix ?
          define right and on whos budget and what kind of budget

          good luck

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