98 ZX2 Engine knock | Ford Escort Owners Association (FEOA)
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98 ZX2 Engine knock

Discussion in 'Introductions' started by Unseen, Jan 27, 2020.

  1. Unseen

    Unseen New Member

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    Greetings everyone,

    I'll get straight to the point, I've got a 98 ZX2 winter beater with 150,000 kms and I've got a loud engine knock. My first thought (hope) was that it was just valve train noise, but it seems to come from deeper within the motor.
    First thing, I searched this forum and the internet and the common diagnosis is bad rod bearings. So I bought new bearings, pulled the oil pan/windage-tray-thing and had a look at the bottom end. Rods had absolutely no discernible slop, but just to be sure I pulled a rod bearing cap (cyl 4) and sure enough it looked virtually brand new.

    So now I am at a bit of a loss. Could it be the hydraulic lifters making that much noise? Maybe the wrist pins are loose? Maybe piston slap? I come from the rotary engine world having owned and RX-7 and RX-8 so diagnosing piston engine noises is new for me.

    Thanks in advance for your help!
  2. Unseen

    Unseen New Member

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    Anybody?
  3. marclar

    marclar Administrator Staff Member

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    what your asking is like going to the doctor and saying... my arm hurts... where does your arm hurt? its my arm....

    there are a gazillion things that can cause a 'knock' and without hearing it, its all speculation. valves, lifters, wirst pin, piston clearance....
  4. Unseen

    Unseen New Member

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    Ok well the sound is not obviously coming from the top end/valve train, it seems to be coming from a bit deeper in the block - as far as I can tell. The sound is also a deeper tone and not a light clicky/tappy sound like valves. I did some tests and if I hold the revs at 2500 and then blip the throttle up, the knock sound gets instantly louder. Based on the advice of a friend who was listening too, he figured it was rod knock. Thats why that was my first thought.

    The sound is loudest at cold startup, gets much quieter as the engine warms up, but it never goes away completely. At light load there is virtually no knock and under load its very noticeable.

    I'm really just asking, based on the history of these motors, what would be the next most likely culprit or item to investigate?
  5. marclar

    marclar Administrator Staff Member

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    that does sound like how a rod bearing would act.. but that also sounds like a text book wrist pin thats hollered out the piston bore. or even an out of round cylinder causing piston slap. either sound almost identical. throttle bliping is really the only way to discover any difference.

    unfortunately, in order to test either of the other issues, the head must come off and the pistons/rods must be pulled.
  6. ZX2.0

    ZX2.0 FEOA Member

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    Can you post a video to hear the mystery sound?

    Sent from my SM-N950U using Tapatalk
  7. Unseen

    Unseen New Member

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    Yeah I'll try and take a good video to capture the sound

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