3rd Gen Toyota Prius drivetrain noise under load – looking for confirmation

2010 Toyota Prius – 186,500 miles

For the past 6 months and 10 000 miles after noticing a rubbing/grinding noise from the driver side, I’ve been chasing a persistent noise and would like to sanity-check my conclusion.

Symptoms:

• Rubbing / grinding / high-pitched whine noise
  
  
• Most noticeable when pressing hard on the gas (power section of the hybrid bar)
  
  
• Occurs while accelerating, cruising, and braking
  
  
• Noise completely disappears when shifting to Neutral, even while moving and braking
  
  
• No warning lights, car drives fine otherwise
  

Work done / ruled out:

• Driver-side CV axle replaced twice
  
  • OEM axle replaced around 177k miles (noise existed before replacement)
    
    
  • Replacements: TRQ first, then Napa
    
    
  • Noise persisted after both replacements
    
• Brake dust shield inspected and bent away from rotor
  
  • Noise slightly reduced, but not eliminated
    
• Transaxle fluid (Toyota ATF WS) drained & refilled ~25k miles ago
  

Key clue:

• Shifting to Neutral immediately stops the noise
  
  
• No noise while coasting or braking in Neutral
  

Current conclusion:
The noise is load-dependent and does not appear to be wheel, brake, or axle related. Symptoms point toward internal hybrid transaxle wear, possibly MG2 or reduction gear bearings, which I’ve seen reported on Gen 3 Prius.

Questions / concerns:

• Does this match MG2 or transaxle bearing wear symptoms?
  
  
• If so, is it generally safe to continue driving as long as no codes appear?
  (I first noticed the noise ~10k miles ago, mid-May 2025.)
  
  
• Has anyone mitigated this without a full transaxle replacement?
  

Thanks for any insight.

 

The noise started before replacing the original CV axle, and didn't go away at all after replacing it both times...