compression test results

Discussion in 'Mechanics Garage' started by adamw412, Jun 14, 2013.

  1. adamw412

    adamw412 New Member

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    Ran it cold because of other problems I am having and got these numbers:

    #1 cylinder: 125psi
    #2 cylinder: 105psi
    #3 cylinder: 125psi
    #4 cylinder: 120psi

    Is #2 cylinder cause for concern? Did it with throttle wide open.
     
    adamw412, Jun 14, 2013


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  2. squirrelman

    squirrelman Member

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    How long did it sit inactive before the test ?? How many miles on the engine ??
     
    squirrelman, Jun 14, 2013


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  3. adamw412

    adamw412 New Member

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    about 2 weeks I think, just under 30K miles
     
    adamw412, Jun 14, 2013


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  4. squirrelman

    squirrelman Member

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    Test it again at operating temperature. 125 psi cold is OK, i believe.
     
    squirrelman, Jun 14, 2013


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  5. adamw412

    adamw412 New Member

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    it's the 105 psi i'm worried about. I can't do it at operating temp, my carb is off and at the shop getting repaired. I redid the test just a few minutes ago after squirting a very small amount of oil in the cylinder and the results jumped up to 125 psi. I guess the rings are going bad on that cylinder. It isn't burning oil. Is it going to do any damage by leaving it alone for now?
     
    adamw412, Jun 14, 2013


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  6. squirrelman

    squirrelman Member

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    No worries. Compression may even out after you ride it a bit. Check the valve clearances on that low cylinder.
     
    squirrelman, Jun 14, 2013


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  7. tinkerinWstuff

    tinkerinWstuff Administrator Staff Member

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    I've always been told results need to be 10% of each other. The test is also supposed to be done at operating temp as squirrelman already mentioned. Being as it was a cold test and you're about 15% of each other, I would sweat it. My money says you'll be we'll within acceptable limits on a hot engine.
     
    tinkerinWstuff, Jun 14, 2013


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