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Compression test
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Thread: Compression test

  1. #1

    Compression test

    Dumb question...

    I have a motor out of the car, on an engine stand, with no starter motor attached.

    I take out all spark plugs, insert compression tester, and crank the motor by hand, should I get a reading?

  2. #2
    Join Date
    Mar 2007
    middle northern Melbourne
    You'll get a reading, it just won't be super accurate.

    Compression tests are usually done at operating temperature as everything has expanded and sealed as much as it's going to.

    Would be OK for checking consistency between cylinders. Could give an idea on 'real' compression depending how comfortable you are with extrapolation.
    Contact me for parts.

  3. #3
    I'm doing something wrong each cylinder is giving a reading of 0 hahaha but can feel a breeze when it turns over. I think I'll try get it going on the stand, mount it side ways to get the gear box/starter motor on it...

  4. #4
    Put the tester on the lawn mower to check the tester and got a reading, so not the tester, both the engines cranking by hand give a reading of 0, I know the 1200 motor went ok, so must need to be turned over at speed??? The other is from Geoff, I know the readings wont be acurate but was a) hoping for a reading and b) hopeing all cylinders would read similar , all ok or all bad hahaha, the spider living the one missing a spark plug will have a sore head

  5. #5
    theres no way you can spin it by hand fast enough
    would be under 10 rpm

    cranking speed is 250 rpm

  6. #6
    Hi Juggs, cool that was my conclusion, cant do this by hand, unless I am really fast

    I know this will vary, but what figures should I see with a cold test? I would have thought a cold test will highlight and major issues?

    I will aim to get it going too, but good to know whether to spend a little time, or a lot of time on this motor, needs a massive clean, welsh plugs, head gasket... and a few new missing parts. That was the extent I was told to do to it, not after a racer, just plod along I have a 1200 too that I know goes, but this one is a 1500, so plod along a bit smoother.

  7. #7
    Join Date
    May 2008
    the wrong side of Melbourne
    chris trying to turn over engine while on ground and take readings could be frustrating as you will need one pair of hands to operate the starter and another to hold the gauge. remember im only 10 min from you and free most nights thats if you doing this after work or your weekends are now free.

  8. #8
    I will get it all setup and let you know, will be in a week or two. Will test the 1200 first, then the 1500, need to swap the fly wheel over...

  9. #9
    Hello, back in the land of the living, free tonight after 7.30 if your around? the only thing I don't have is jumper cables...

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