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Compression test results and ?

Discussion in 'General Tech and Maintenance' started by hondadriver, Jul 4, 2004.

  1. hondadriver

    hondadriver Member

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    I have a 2nd gen JDM b16a in my 98 lx, and when I check my oil it always seems like i'm losing some ( not major) , so I did a compression test ( even thought the place I bought it from said they did one already) So my results are like this:

    Cyl #1 = 195
    Cyl #2 = 200
    Cyl #3 = 200
    Cyl #4 = 210

    It looks like i'm fine, they are all within 28 psi. I didn't do the test with squirting oil into the cylinders because none of my numbers are really low. Becasue in the haynes book it says if any of the tests come out lower then normal add 3 squirts of oil into each cylinder and redo the test.

    But my question is, in the book its says on the first crank if the compression is low then gradually increases this means you may have worn rings. But how low is low? Like when I did the first crank it went up to 120 then it went up from there and I cranked it 7 times to get the above results.

    And before i did the compression test I did the vacuum test, and the book says a normal engine at idle should be between 17- 22 hg. Mine at idle stayed at at 22hg, so that test was came out good also.
     
  2. hondadriver

    hondadriver Member

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    Does anyone now from there own experience on doing a compression test. Is it suppose to go up to 190+ on the first stroke. OR does it start alittle low like 120 then build up. Becasue I did a search on yahoo, and other people with b16a's have around 200 psi on there test also, which means i'm up there but I wanna now what is it suppose to be at on the first stroke. Because the book is not clear enough!! Its says if its low on the first stroke, then builds up in psi then rings may be worn. Can someone clear this up for me!
     
  3. JDMilan

    JDMilan Senior Member

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    I had I think 210 across, if some are higher it's ok but I am not sure on the exact figure on what the largest difference between firing cycles would be, I thought it was a max of 20.
     
  4. phunky.buddha

    phunky.buddha Admin with a big stick Admin VIP

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    You always want to run 8 pumps to reach your maximum pressure on the compression test. You're never going to reach max psi on the first pump- trust me. If you're already at 120psi on the first pump and you top out at 200psi, you're fine.

    The compression test only checks a few areas for leakage like the rings and valve seats- but it doesn't tell you exactly where, and it definitely doesn't tell you what is wrong. All it indicates is that something is wrong in a particular cylinder. You're probably not leaking oil past your rings.

    Your oil control rings could be bad, your valve seals could be bad, you could be leaking a bit of oil through a break in your head gasket- there's a ton of things that could be wrong. If you want a better diagnosis, get a leakdown tester and check everything out again.
     
  5. hondadriver

    hondadriver Member

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    oil control rings? Where are those I'm looking in a book, they don't come to mind! And if the compression test, tests the rings and valve seats then that means the valve seats are ok then. Right, I didn't now there was a leak down tester, i just thought a leakdown test was when you squirt some oil down on your pistons so that it seals the rings while you redo the compression test! Thanks for the info! And it feels good to now that it PROBABLY isn't my rings becasue I don't have the time nor do I wanna go through all that again. If the problem is in the head then thats a ton easier!
     
  6. phunky.buddha

    phunky.buddha Admin with a big stick Admin VIP

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    The oil control ring is the lowest ring out of the three on your Honda piston.

    A leak down test basically takes a measured pressure (usually 100psi) and feeds it into a cylinder, then checks to see how much pressure the cylinder is actually holding. The last leak down test I performed on my engine showed 99psi out of 100, so it was only leaking 1%. One major advantage of the leakdown test is that you can sit there and examing the engine while you have a cylinder pressurized- with a probe on the end of a stethoscope, you can find out exactly where you're leaking from.
     
  7. hondadriver

    hondadriver Member

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    Is that 1% leak ok, I mean if you leak alittle is that fine Or should it be 100% of what psi you are putting in there? Thanks alot for the info, I'm retarted for asking what those rings were, it took me a while to figure it out what they were, becasue I was sitting next to my buddy while he was filing down his rings over the winter when we did his b16 bottom end, I don't now I guess I had a brain fart! But thanks for all this info, becasue I never did a compresion test, but now I know how to do one.
     
  8. phunky.buddha

    phunky.buddha Admin with a big stick Admin VIP

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    Most of the time up to a 5% leak is acceptable, up to 10% and you should start worrying... more than 10% you've got some serious problems.
     
  9. TechChris

    TechChris Member

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    Hi

    To me it sounds like your rings are ok. I would recommend pulling the head getting a valve job done and have new valve seals installed. This should only run you between $175- $250, if you pull the head yourself.
     
  10. phunky.buddha

    phunky.buddha Admin with a big stick Admin VIP

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    Run the leak down test first before you tear your engine apart.
     
  11. hondadriver

    hondadriver Member

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    Ok thanks for all the info, I appreciate it!!!!
     
  12. JDMilan

    JDMilan Senior Member

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    :werd: go with what E said.
     
  13. phunky.buddha

    phunky.buddha Admin with a big stick Admin VIP

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    E never posted in this thread?
     
  14. hondadriver

    hondadriver Member

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    Hey Calesta, I just don't understand one thing, you said yours was leaking 1%. how do you figure that out? Becasue, say you put 100 psi into a cylinder and then it starts to leak, its not gonna leak and then stop at a certain point. How will I now what percent I'm leaking? Is it based on how fast it leaks out or??
     
  15. phunky.buddha

    phunky.buddha Admin with a big stick Admin VIP

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    No, you're constantly feeding it 100psi of pressure. There are two pressure guages on a leakdown tester. One reads the pressure in the air line going into the engine (100psi typically), and one reads the pressure that's held inside the cylinder. Mine read 100psi on the input line, and the second gauge read 99psi. That's 1psi out of 100 leaking, so only 1% leakage.

    You don't pressurize the cylinder and then stop- it's always under pressure. That's how you're able to listen to the engine with a probe and stethoscope and check for where your leaks are too.
     
  16. hondadriver

    hondadriver Member

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    OH, ok I understand. Thanks!!!
     
  17. phunky.buddha

    phunky.buddha Admin with a big stick Admin VIP

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  18. cws13

    cws13 Senior Member

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    1% Cal....very nice, better than out of the box!
     
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