Thread: knock knock

  1. #1
    bradleyheathhays's Avatar
    bradleyheathhays is offline Senior Member
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    knock knock

    96 XJ here, 180k 4.0. Recently I've had a repetitive knock sound show up. You don't hear it on a cold start but after it warms up there's a distinctive lower pitched knock with a frequency of about 10 times a second, at idle. Seems to be coming from the bottom of the car/engine as you can hear it better from the sides and rear. The normal engine sounds seem to drown it out when you listen from over or in front of the engine. Not sure if the knocks increase in frequency along with acceleration.

    Any ideas?

  2. #2
    JPNinPA's Avatar
    JPNinPA is offline Senior Member
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    Re: knock knock

    Loose exhaust- pipe banging oil pan.
    Leaky exhaust at a cylinder - #5 or 6 exhaust bolt comes loose.
    Broken piston skirt


    Sent from my iPhone using Jeepz.com mobile app
    "Never look down on anybody unless you're helping him up" - Jesse Jackson

  3. #3
    bradleyheathhays's Avatar
    bradleyheathhays is offline Senior Member
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    Re: knock knock

    My knock sounds exactly like whats in the video where the guy is fixing his loose flexplate bolt.


    https://www.cherokeeforum.com/f51/ho...ocking-125547/


    Is there any danger in running it like this for a few weeks? I've got a more pressing problem with my other car I'm trying to take care of right now.

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