Drivetrain - Knock at startup but sounds ok after that. | Ford Escort Owners Association (FEOA)
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Drivetrain Knock at startup but sounds ok after that.

Discussion in 'ZX2 1998-2004 2.0L DOHC' started by Maximus Powers, Jun 3, 2019.

  1. Maximus Powers

    Maximus Powers New Member

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    So I have an 2002 zx2 with an auto trans. It makes a nasty knock when I start it, but after it starts it sounds fine. The car has 69,300 miles. My college age son purchased it a year ago from a used car lot.
    It has been sitting mostly unused for over 9-10 months. When he was last driving it regularly, it developed a leak in one of the transmission lines. He noticed the car was having trouble shifting while driving to his first day of class at the college he was attending. He drove it low on trans fluid over 60 miles to and from school. Surprisingly, it made it home.
    So, I changed the rusty lines and filled the transmission to a correct level, and it seems to shift correctly. The issue is as stated, it still makes the knock at start up. Last fall I checked all the easy stuff. There were no loose engine mounts, exhaust parts, heat shields ect. I also pulled the serpentine belt and checked the alternator, p|s and a/c. They all spin free. I checked the starter also, it seems fine.
    The knock sounds internal, but it's not faint by any means.
    My best guess now is that the flex plate is cracked. I really don't want to put in all the work tearing it apart, to find out that the flex plate is fine.
    He was trying to sell it, but no one was really interested. He's looking to move out, so I gave him some cash, and now this car is my problem.
    So, does anyone have any ideas?
  2. Joey_Twowagons

    Joey_Twowagons FEOA Member

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    Does it make the sound in neutral, and more or less coinciding with engine speed? How long does it take to go away?
  3. Maximus Powers

    Maximus Powers New Member

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    There isn't really any abnormal sound after the engine is running. It goes away after the engine starts. There may be some mild lifter chatter, but that's all I've noticed. The starter also seems to be functioning correctly. That's why I was thinking that it might be the flywheel.
    I guess there's a possibility the issue could be something inside the torque converter.
  4. denisond3

    denisond3 Moderator Staff Member

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    The torque converters are pretty durable. With old age they may develop a worn thrust bearing, and the edges of the impeller blades can abrade the frame of the stator - but this would not be a short term loud noise, would instead by a soft constant hum.
    So I would start by doing a compression check - and let us know if one or two cylinders are close to zero. I have never worked on a ZX2, so am just guessing. Does one of the camshafts have a means of varying its position, like the BMW engines do? On a BMW it called the VANOS, and can be quite noisy. Other things that can cause a noise would be a loose bolt bolt on the pulley spinning one of the camshafts.
    The flex plate crack would be a noticeable noise, but I think it wouldnt stop after the engine was running; rather it would settle into a very definite clattering at an idle, when the crankshaft was changing its rpm with every power stroke while the torque converter (and the flex plate) would want to be turning at a constant speed.

    Good Luck.

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