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compression testing

Discussion in '80-Series Tech' started by GhostCruiser, Aug 27, 2003.

  1. GhostCruiser

    GhostCruiser

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    I had a compression reading when I first bought my 92 FJ80.

    The first test was in April 2002 @ 138,000 miles.

    Yesterday I had it tested again at the same independent toyota repair shop.
    w/ 150,000 miles

    First test #1-145 #2-145 #3-140 #4-140 #5-140 #6-135
    Second test #1-130 #2-125 #3-125 #4-125 #5-135 #6-130


    Does that seem possible? That kind of drop in a year and a half with 12,000 miles? I changed oil close to every 2,000 miles.
     
  2. yomama

    yomama

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    Ghost,

    I wouldn't worry about it too much. There can be many variables that could explain the different readings. How many readings did they do on each cyl, did they average the tests, was it a peak reading, was the engine temp the same as last time, did they use the same gauge, was it the same technician?
    Unless you have one cyl showing NO compression or below 100 I wouldn't worry about it. Check it again at 200k and see what you get. :)

    Yomama
     
  3. cruiserdan

    cruiserdan SupportingVendor Emeritus Supporting Vendor Moderator

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    Ghost,

    I second Yo's comments. There could be that much varation between gauges alone. In addition the high set could be "wet" readings and the low set "dry" readings.
     
  4. nakman

    nakman addict. Supporting Vendor

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    That difference could be caused by the amount of charge in your battery. Often times you'll see #6 get a lower reading than the first 5, and you're convinced you've got a bad head gasket when in fact you just ran your battery down cranking away doing the test. Any chance you had a new battery a year ago, and are still running the same battery? just a thought...
     
  5. GhostCruiser

    GhostCruiser

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    Actually I just put a Toyota battery in about 3 monthes ago.
     
  6. landtoy80

    landtoy80

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    Could if ba carbon build up? Run a can of BG44k, Seafoam in gas tank or in vacuum hose per can (Seafoam). Run BG crankcase cleaner or Seafoam in the oil or have the motor decarboned at shop. My 2F gained campression after I cleaned and decarboned the motor. Get your own tester and test your self. I just got a new compression/fuel presser tester the other day. Now I have 2 comp. teaters. I will test them both and see how close they are.
    kurt