LG top washer making clanking sound only when washing / agitating

Washer Repair
1

Brand: LG
Model Number: WT7800CV
Main Symptom: clanking sound
What happens & when: clanking sound when washing / agitating

Error Code (if any): NA
Parts or tests already tried: no parts replaced yet, checked the bolt under cover plate which secures washing / agitating plate inside the tub and it’s secure not loose

Spin cycle works fine

On video below you can see the tub spins freely without any abnormal noise, when engaging agitating bottom plate by hand to simulate the issue you can hear loud clanking noise. Appear to be coming from the bottom of the machine.
Photos / video link: Imgur: The magic of the Internet

2

I would start by checking the washplate. It is splined onto the transmission output shaft, and sometimes those splines can wear and allow the washplate to slip on the shaft.

Remove the cap and the bolt/nut holding the washplate in place, then pull the washplate off. Inspect both the internal splines in the washplate and the splines on the transmission shaft. Look for rounded, stripped, or damaged splines.

Test the transmission

If the splines look good, leave the washplate off and use a pair of pliers to carefully grip the transmission output shaft. Move the shaft back and forth like you were doing with the washplate.

Pay attention to where the noise is coming from. There will normally be a little movement in the drive system, but you shouldn’t have excessive looseness, grinding, popping, or rough spots coming from inside the transmission.

Next, unplug the washer and remove the rotor from underneath the machine. With the rotor removed, turn the transmission shaft by hand from the top again.

This is a useful isolation test because the rotor/stator is now disconnected from the transmission. If you can still reproduce the grinding, clicking, or knocking noise with the rotor removed, the transmission becomes the main suspect.

Check the rotor and stator

With the rotor removed, inspect the inside of the rotor carefully. Look for:

  • Cracked or damaged magnets
  • Loose magnets
  • Scrape or rub marks
  • Metal debris
  • Signs that the rotor has been contacting the stator

Inspect the stator for cracked sections, loose mounting bolts, damaged windings, or obvious rub marks.

Also check the rotor mounting bolt and make sure the rotor isn’t loose on the transmission shaft.

Before reinstalling the rotor, rotate the transmission shaft by hand and listen again. Then reinstall the rotor and rotate it by hand.

If the noise is present with the rotor removed: I would suspect the transmission/gearcase.

If the transmission is quiet with the rotor removed but the noise returns after the rotor is installed: concentrate on the rotor/stator assembly, its mounting, or the rotor rubbing against the stator.

That should help isolate the noise before replacing either assembly.