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  • Cylinder compression and proper way to test?

    What is the proper cylinder compression ratings for the festiva? And what is the proper way to test it?

    I disconnected the coil hooked up the compression tester and turned the engine over a few times on each cylinder leaving the other plugs in of course...

    What I found was starting at the passenger side working to the right 35psi 135psi 90psi 80psi

    Now I know that those readings pretty much mean a pooched engine but I just wanted to find out what the actual proper readings should be and if I was doing the compression test right....
    90 festiva BP/G25MR swap, spec v seats, aspire brakes, FMS springs, round headlight conversion with HID's, custom exhaust, fiberglass hood, and a whole lotta bodywork
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  • #2
    I believe 180 psi is what they should be...?? Or close to that. I don't have the manual in front of me....
    I'd say 1 (really bad),3 and 4 cylinders are leaking bad... if you get 135-160 psi with all your readings, you'd be fine...
    As far as testing, take all your spark plug out... then do each one with your tester and cranking the engine. This way, for the other 3 cylinders there isn't any cylinder pressure and you'll get more accurate results from your reading.

    -"Hairlipstiva" 1991 GL 5spd (swapped from an auto), rolling on Enkei 14x6 +38 with 195/45/14 Toyo's, Jensen MP5720 CD deck, tach install, LED strip in cluster, down position rear wiper, FMS springs, Gabriel shocks on 4 corners, Acura Integra short shifter
    -Escort GT 91 donor car with BP, G5M-R tranny to be dropped in the little guy...
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    • #3
      The cylinders should be within 75% of each other. The range should be aroud 101 to 135 based on your highest compression. The Festiva shop manual I have shows the max ranges from 134 to 260 and what the minimums for each of these are.
      Last edited by hawkdoc60; 02-12-2009, 10:23 AM.
      http://www.cardomain.com/id/hawkdoc60

      01 Chevy Impala 9C1 police package "Unnamed yet". 154K
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      06 Ford F-150 Pickup Replacement for my 2001 Impala Cop Car that lunched its engine.

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      • #4
        Crank the engine over 5-10 times until the reading is stable. The compression should rise quickly on the first few revolutions. Do it a second time after putting a spoonfull of oil in thourgh the spark plug hole, called dry-and-wet test. The difference gives an idication of the condition of the rings.
        Haynes manual suggests normal is 204 psi (1412 kPA) @ 200 rpm, and at 149 psi (1030 kPA) it's time to consider an engine overhaul.
        When I first tested the compression on my '89 in '98 it was 185-195 or 5.4% dry and 185-200 or 8.1% wet. A chemical engine additive brought the variation down to 2.7% dry and 4.4% sweet. The most recent test in 2004 was 185-190 or 2.7% dry and 187-195 or 4.2% wet. This engine has only 110k km on it in 2009.
        You can also look for carbon discolouring on the underside of the valve cover as an indication of stuck or leaking exhaust valves. A dirty exhaust valve on #3 cyclinder on my car showed up that way. The chemical additive cleaned that up.
        Original owner of silver grey carburetted 1989 Festiva. 105k km as of June 2006. 140k km as of June 2021.

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        • #5
          Originally posted by LittleHoe View Post
          What is the proper cylinder compression ratings for the festiva? And what is the proper way to test it?

          I disconnected the coil hooked up the compression tester and turned the engine over a few times on each cylinder leaving the other plugs in of course...

          What I found was starting at the passenger side working to the right 35psi 135psi 90psi 80psi

          Now I know that those readings pretty much mean a pooched engine but I just wanted to find out what the actual proper readings should be and if I was doing the compression test right....
          ok, there's few things you did wrong, that will definately skew your readings...

          First remove all spark plugs before beginning any test. Having just one plug will skew your readings.

          Second, after disabling BOTH ignition AND fuel, block the throttle wide open. Again, not doing these will skew your readings. If you don't disable the fuel, you can still inject fuel during the test, and the fuel will wash down the cylinder walls, lowering the reading. If you don't block the throttle open, the amount of air able to get into the cylinder will be resticted, lowering your readings.

          Third, hook up a battery charger on it's highest setting. As you do the test, the cranking speed will slow, due to the battery being discharged during cranking. Its very important to check all cylinders at the same cranking speed. A change in speed will result in a change in your reading.

          Last, after checking all four cylinders dry, add a teaspoon of oil to each cylinder (one at a time, just before taking a reading on that cylinder), and run the test again. If the compression reading does not increase significantly, then your issue is most likely a leaking valve or blown head gasket. If the reading improves dramatically, then your issue is the piston rings.

          Your readings should be within 10% of one another (ie; 90, 100, 110, 100). A properly sealed 1.3 usually gives readings in the 160-190psi range. A slight drop (10-20psi) is usually indicative of normal wear/high mileage.
          Last edited by FB71; 02-12-2009, 11:41 AM.
          Jim DeAngelis

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