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Thread: Cylinder compression results - dry/wet

  1. #1
    LXi User AC439's Avatar
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    Mystery after leak down and Cylinder compression results - dry/wet

    I have finally gotten a compression gauge from HF and just did my test. Numbers are not too good:

    Dry:

    Cylinder 4 / 3 / 2 / 1
    Try #1 - 137 / 127 / 124 / 134
    Try #2 - 137 / 129 / 123 / 134

    Max cylinder difference is 137-123 = 14 psi

    Then I put about 2.5 mL of engine oil in each cylinder, spin the engine few times to let the oil spread and did the WET test:

    WET:
    Try #3 - 145 / 135 / 130 / 137
    Try #4 - 145 / 134 / 128 / 136

    Max cylinder difference is 145 - 128 = 17 psi

    So with the little increased in compression in the wet test (max increased 8 psi, cylinder #4 & 3), I think the rings are in pretty good shape. This has pretty much confirmed my suspicious of cylinder head likely leaky valve seats (by process of elimination).

    The car never gives blue smokes. I know my next is leak-down test. But if the wet/dry test pretty much says problems in the head, do I still need to do lead-down if I ended up need a new head of rebuild it ?

    Also, I searched and the service limit is all over the place. I have seen from 120 to 160 psi. Snooz once posted the service limit is 135 psi according to Honda.

    - AC
    Last edited by AC439; 06-30-2019 at 07:50 AM.



  2. #2
    3Geez Veteran
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    Re: Cylinder compression results - dry/wet

    compression sounds low but the cylinder balance is good. I think its 170's stock new.
    1988 Lxi owner since August 1995
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  3. #3
    LXi User AC439's Avatar
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    Re: Cylinder compression results - dry/wet

    Forgot to mention, I did the test when engine was cold.

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    Re: Cylinder compression results - dry/wet

    That difference between cylinders could well be what you're noticing. It's an old engine. They develop character.
    Last edited by Dr_Snooz; 06-13-2019 at 08:28 PM.
    Dr_Snooz

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    Re: Cylinder compression results - dry/wet

    Do a test when hot , things tend to come up a bit .
    My fresh as 10.8:1 comp B20a only has 150 across the board cold , but it has massive overlap cams .

  6. #6
    LXi User AC439's Avatar
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    Re: Cylinder compression results - dry/wet

    I will do another test again when engine is warned up. I will see what numbers I get when it is hot.

    I went back to the FSM. It says service limit is 142 psi (except A20A4, 149 psi). New engine is 171-178 psi. Max variation between cylinders is 28 psi.

  7. #7
    LXi User AC439's Avatar
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    Re: Cylinder compression results - dry/wet

    Ok, just did a warmed engine compression test. Its not a lot of difference though.

    Hot engine:

    Cylinder 4 / 3 / 2 / 1
    Try #5 - 137 / 133 / 130 / 136
    Try #6 - 138 / 134 / 131 / 137

    I didn't do the wet oil test.

    I think my block seems fine and it is in good tolerance. Last time I did my HG, I noticed the cylinder walls are very very smooth and looking good.

    My next up will be leak-down test. I am more leaning towards head problems......

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    SEi User Hauntd ca3's Avatar
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    Re: Cylinder compression results - dry/wet

    how smooth is smooth ?
    most engines i've pulled down still show the hone marks even if they are burning oil .
    really shiny bores arent a good thing in my experiance

  9. #9
    LXi User AC439's Avatar
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    Mystery still

    I did the leak-down test today with HF leak down tester.

    The worse leakage is no more than 15%, which is on cyl #2. I did it 3 times - average: Cyl 1 - 9%, #2 - 14%, #3 - 13%. #4 - 9%.

    I saw absolutely no bubbles on radiator - no leaking into coolant.

    No air leak noise on intake butterfly (close & open)

    No air leak noise on exhaust.

    Little noise on oil dip stick (some leak through the rings).

    People criticize the HF leak down tester for it operating at 15psi, but usually say lower pressure will yield valve problems. I did it according to the instructions.

    I'm still scratching my head cause the head\valves were the biggest suspect. Now they seems seating and sealing fine.

    After the test, I was like what the heck so I changed the oil with a new filter and poured in "Restore". Since my wet compression test didn't yield a significant increase in compression, I have not been thinking about the rings. I went out for a road test for 6-7 miles. The vibration at 2k seems a little less and the car feels a little more power, but this could be my speculation. People are saying Restore needs a few hundred miles to see effect so I will keep driving it and see what happen.....
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    Dr_Snooz's Avatar
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    Re: Cylinder compression results - dry/wet

    What weight oil are you using?
    Dr_Snooz

    "I like to take hammers, and just break stuff, just break stuff." - Beavis


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  11. #11
    LXi User AC439's Avatar
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    Re: Cylinder compression results - dry/wet

    Quote Originally Posted by Dr_Snooz View Post
    What weight oil are you using?
    10w-30 Castrol all the time.

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    Re: Cylinder compression results - dry/wet

    There goes that theory.
    Dr_Snooz

    "I like to take hammers, and just break stuff, just break stuff." - Beavis


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  13. #13
    LXi User AC439's Avatar
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    Re: Cylinder compression results - dry/wet

    Quote Originally Posted by Dr_Snooz View Post
    There goes that theory.
    I don't even know what theory applies to my car anymore. I think I have tried many things and ruled out many things as well. Absolutely inconclusive.

    I have logged 110 miles since using Engine Restore. The car's peppiness has returned. The 2k vibration seems less but it is still there. I will continue driving the car and post again after I have more miles on the Restore.

    But I'm at a loss after compression and leak down test. If Restore can do its magic, I will continue using it. I think I have the gut feeling sometime later (winter time) I will have to pull the head out again and take it to a head shop. Maybe something I missed about the head that I haven't been able to notice...
    Last edited by AC439; 07-13-2019 at 09:24 AM.

  14. #14
    LXi User AC439's Avatar
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    Re: Cylinder compression results - dry/wet

    I have done one more thing - valve adjustment.

    I always adjust to the middle of the range but this time I have adjusted them towards the loose end but still within spec. Someone said it will improve compression since the valves are closing a little earlier and opening a little later. I do notice the vibration became a little lesser and the car is more drive-able. I will log about 500 miles from adding restore and do another compression test to see if it improves the compression too.

  15. #15
    LXi User AC439's Avatar
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    Re: Cylinder compression results - dry/wet

    So after 525 miles with Restore, I did another compression test (dry / engine cold condition). The result are literally about the same before using Restore, except it does help cylinder 3 some. I noticed the peppiness has somewhat back down a little and the 2k vibration is still there.

    525 miles after Restore, Dry/cold engine:

    Cylinder 4 / 3 / 2 / 1
    Try #1 - 138 / 135 / 125 / 130

    before Restore, Dry/cold engine
    Cylinder 4 / 3 / 2 / 1
    Try #1 - 137 / 127 / 124 / 134
    Try #2 - 137 / 129 / 123 / 134

    I wonder if I can conclude that if Restore does not raise cylinder compression noticeably, it may indicate the cylinder wall / rings are in relative good shape ? The lower than service limit compression result maybe an inherently characteristic of my engine.

    I also got a vacuum gauge from HF and the intake manifold vacuum is at 19 in Hg. Momentally open and close throttle, it dropped to ~7 and bounce back to 23-24 then stablized at 19. I noticed right after car stated (cold engine) the vacuum was at 17, then it stablized at 19 within 2 seconds. I think it is because the pistons are getting warmer and tolerance is reduced. But overall, the vacuum is at 19 and at the middle of the green zone on the meter.

    Also the needle does vibrate rhythmically but only very little like within 0.2 in Hg so there may be an indication of a minor valve issue.

    All these results are so subtle for me to properly interpret what the problem is so I will visit a local head shop and bring all my findings to see what they say.

    I still want to fix this problem so the car can be used as semi-daily....

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