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Recurring compression loss on #3 900 1994

posted by  Boyce on  Fri Nov 24 03:27 CST 2006
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last visit: Thu Oct 30 05:32 CST 2008
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I have a 1994 940 Turbo Wagon with 115k. A rough idle/poor perfomance issue was diagnosed 8 months ago as low compression on #3. A valve check revealed poor clearance. The clearance issue was adjusted and compression returned to normal. Low compression is now present again on #3. Any ideas? Bad cylinder head?








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    Recurring compression loss on #3 900 1994

    posted by  B.C. on  Fri Nov 24 06:17 CST 2006
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    last visit: Wed Mar 28 22:28 CST 2012
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    Any possibility that one of the #3 valves is sticking in its guide? Having only one cylinder acting up, rather than all four, seems unusual to me.

    By clearance do you mean valve lash? The clearance between the cam lobe and the valve? Seems to me that a bad clearance would not make as much difference as you are experiencing. How much was it adjusted?

    Do the "wet" compression test suggested, it can be revealing.

    Good Luck,

    Bob

    :>)








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    Recurring compression loss on #3 900 1994

    posted by  mobetta on  Fri Nov 24 06:03 CST 2006
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    last visit: Sat Jan 21 09:34 CST 2012
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    re-check the valves. if they came out again, there is a chance the head is warped. if valves are good, do comp. check, adding a little-Tbsp- of oil thru the sparkplug hole. receck comp. if it goes way higher, there may be a ring issue.
    of course i have been wrong before.....








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      Recurring compression loss on #3 900 1994

      posted by  Boyce on  Tue Nov 28 03:18 CST 2006
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      last visit: Thu Oct 30 05:32 CST 2008
      [RELATED]

      The wet test produced the same results. I assume I have worn or burned valve on #3. The car burns 1/2 quart every 5k but I was told that is common on Turbos. Is that correct?

      I am going to get a remanufactured head and see if that fixes the problem. I am going to file another post for things to do while I am at it.

      Boyce






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