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  • noisy valve train

    The collective experience and wisdom on this forum is astounding, so I would like a dose or two of it. I have a 95 with the 4.0. The Jeep has 72000 odd miles on it, and runs like a top. However, I have been climbing the Blue Ridge Mountains (pavement, unfortunately), a bunch here lately, and am hearing alot of valve train chatter during hard pulls. When I drop a gear (auto), it is still there, even though it isn't pulling as hard. Is this normal, and if not, how should I proceed? Higher octane gas? Adjust the valves?
    I have only heard this since I have been driving the mountains. No noise on flat driving, accelerating, small climbs, etc. The oil is clean and full, good pressure, and engine temp is fine.
    Thanks in advance!
    95 Wrangler YJ I6 32RH auto 31x10.50's

    Romans 1:16 For I am not ashamed of the gospel of Christ...

  • #2
    That sounds like "pinging" which is pre-ignition. Have you checked your distributor timing?...
    AFSOC, retired...
    "Here's my strategy on the Cold War: We win, they lose". - Ronald Reagan-

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    • #3
      Have you checked your distributor timing?...
      You can't adjust the timing on it, you can turn the distributor all you want the ECM will adjust around it.
      95 YJ: 4.0, AX15, SOA, 4" leafs, 1" shackles, 3" body, SYE, CV driveshafts, locked 44, locked 8.8, high steer w/crossover, 37x12.5's on 15x10 beadlocks, OBA, winch, and a few other things. My Build-Up Post -- Photos -- SWB FAQ -- Mike

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      • #4
        Have you tired running any cleaners through it, like SeaFoam?
        95 YJ: 4.0, AX15, SOA, 4" leafs, 1" shackles, 3" body, SYE, CV driveshafts, locked 44, locked 8.8, high steer w/crossover, 37x12.5's on 15x10 beadlocks, OBA, winch, and a few other things. My Build-Up Post -- Photos -- SWB FAQ -- Mike

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        • #5
          Originally posted by OhioYJ:
          </font><blockquote>quote:</font><hr />Have you checked your distributor timing?...
          You can't adjust the timing on it, you can turn the distributor all you want the ECM will adjust around it. </font>[/QUOTE]With no distributor on my 2000, I guess I'll have to learn more . Doesn't that distributor use a vacuum advance?...
          AFSOC, retired...
          "Here's my strategy on the Cold War: We win, they lose". - Ronald Reagan-

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          • #6
            Doesn't that distributor use a vacuum advance?...
            Nope you are thinking of the 4.2 motors, those you can adjust the timing, if you do the Nutter Bypass you get complete control of the timing.

            However on the 4.0s when they went EFI, there isn't a way to adjust the timing, unless you flash the ECM, or use an adjustable CPS. You can rotate the distributor almost 180 degrees in some cases and the ECM will continue yo curve around it, once you turn it too far, the motor will just die.
            95 YJ: 4.0, AX15, SOA, 4" leafs, 1" shackles, 3" body, SYE, CV driveshafts, locked 44, locked 8.8, high steer w/crossover, 37x12.5's on 15x10 beadlocks, OBA, winch, and a few other things. My Build-Up Post -- Photos -- SWB FAQ -- Mike

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            • #7
              Interesting...
              AFSOC, retired...
              "Here's my strategy on the Cold War: We win, they lose". - Ronald Reagan-

              Comment


              • #8
                Go ahead and try a tank of 93 octane. if i is pinging it will solve the problem and you WILL notice an improvement in power and economy. I have found many high mileage 4.0'sexibit some knocking at idle. ibeleive this to be piston slap. Good Lack
                1954 Willys Overland Wagon 88YJ with 4.0, AX-15, 2\"BDS SOA, Hi-Steer, 36\" Swampers, High Pinion D-44 and a Ford 9\" with 4.56s\'s, Locked F&R, AA SYE with custom HD Drive shafts, Motorcraft 2150, GM HEI, OBA system, Warn 8274, A LOUD air horn, and a hole in my wallet.

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                • #9
                  Could just be a small exhaust leak. Sometimes it can sound like valvetrain noise.
                  97 TJ 4popper 2" BL, 4" RC long arm lift, SYE, 36" TSL's, 8.8 swap, BTF bumper, Herc'd tub, Homebrew flatties, Viking top, Fuel cell, LED's all 4 corners.

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                  • #10
                    I will run a tank of 93, as soon as I empty this one, and see if that takes care of it. It would certainly be nice. Thanks for your replies!
                    95 Wrangler YJ I6 32RH auto 31x10.50's

                    Romans 1:16 For I am not ashamed of the gospel of Christ...

                    Comment


                    • #11
                      Originally posted by OhioYJ:


                      However on the 4.0s when they went EFI, there isn't a way to adjust the timing, unless you flash the ECM, or use an adjustable CPS. You can rotate the distributor almost 180 degrees in some cases and the ECM will continue yo curve around it, once you turn it too far, the motor will just die. [/QB]
                      X2. The computer has complete control over the distributor via the cam sensor inside of it.
                      97 TJ Sport<br /><br />Artillery brings dignity to what would otherwise be just a brawl

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                      • #12
                        Originally posted by bullfrog:
                        Could just be a small exhaust leak. Sometimes it can sound like valvetrain noise.
                        When under a load, sure.
                        97 TJ Sport<br /><br />Artillery brings dignity to what would otherwise be just a brawl

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