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A cracked flex plate (flywheel) could be your problem.
It sure does . Almost like a rod knock . But with a crack flex plate if you press and hold the brake pedel and step on the gas pedel just a little the noise goes away .. With a rod knock the noise gets louder and faster as you step on the gas..
remove engine or transmission replace flex plate (flywheel).
You have to pull the engine or transmission. The Flex plate is at the back of the engine on an automatic transmission. 6-8 bolts hold the plate to the engine, and four bolts hold the plate to the tranny.
If it really IS the flex plate, that's a lot cheaper than other problems that could cause a bad knock. The flex plate is a steel plate that bolts to the rear of the engine and has gear teeth around it. The starter engages with the teeth to start the engine. The torque converter also bolts to the flex plate. All power produced by the engine that is used to move the vehicle goes through the flex plate. Flex plates get old and sometimes crack. When that happens you want to get the old flex plate out of there as soon as you can before it breaks completely and destroys the torque converter. A flex plate is relatively cheap, compared to a complete engine rebuild or replacing the torque converter. To replace the flex plate, simply pull the engine (or transmission, whichever is easiest), unbolt the flex plate from the crankshaft, bolt up a replacement and put the transmission (or engine) back. Of course, there is more involved than that, but it's not as bad as some repairs.
If you are really talking about an automatic transmission flex-plate, then a clicking noise at a lower rpm that seems to go away as yoiu wrap up the motor would indicate a crack. A maual transmission's flywheel that is cracked will generally cause the cluth to slip, and eat the clutch disc rapidly. There will be a strong smell!
the purpose of the flex plate is the same as a flywheel. when the starter is engaged, it spins the flex plate, thus hopefully starting the engine.
loud rattling noise when idling.
Vibration, Clunking noise, starter not working correctly.
Flex plate
You may have a cracked flex plate.
Loose timing chain? Loose heat shield on catalytic converter?