Engine braking sound

welcome!
your first sentence says 'on acceleration on braking'. could be a wheel bearing, cvj, or other moving parts.or brake pads, shoes, etc.
if you don't have any dash trouble lights on, it may not be serious. how are your mpg's?

 

Maybe get a dealer to diagnose it or a Prius expert

 

Can you rephrase/clarify that, especially the bit I've made bold? I'm not understanding.

I think too, dealership, hopefully a competent one, would be your best bet.

 

i guess i wouldn't look at the tranny then, but anything is possible.

 

One clue, however inscrutable: it's definitely sounding different than in the past? I think a test drive with a dealership mechanic might move things along.

 

unless he knows what he's talking about. or, you could just have the indy replace the tranny and see what happens. will he guarantee it?

 

agreed.

 

Is this sound made (during acceleration / braking) all of the time, or just sometimes?

 

Does the HV battery show fully charged when this happens?

 

The first time my engine raced/revved high was upon coming to a complete stop after climbing a larger hill and coming half way down the other side to a signal light. I thought the pedal was stuck or something was broken, I panicked internally then I moved the lever into neutral, but the the high RPM sound continued (it stopped a couple of seconds later and I put it back into drive and took off).

I've read that the battery thought it was too full and needed to discharge some energy by spinning the motor at a greater speed (wish there had been an idiot light for when this is happening).

The above doesn't sound like the same problem, but might be battery related.

Is your engine (braking or high RPMs) noise source coming from the engine? (*does it sound the same as if you had pressed down on the gas pedal)

 

I'd invest the $50~100, whatever it takes, for them to just have a look at it, for sure including a test drive, where you can point out the sound, see what they say. If you're definitely noticing a new and different sound, something is not right.

Could even be the muffler going, for example.

 

SFO, Ive been searching all over the internet for information about my prius and you're comment caught my attention. I have a 2008 prius with 160K that has recently started driving exactly as atomic described (engine braking). My HV battery is almost always full or near full (always green) after I start driving. The threads about green batteries suggest checking my 12V and I just did that and mine seems fine (maybe a little weak ~13.8V once I started the car (ready), ~11.8V car on). My engine sounds exactly the same as if I had pressed down on the gas pedal and is most noticeable at highway speeds even when my foot is off the gas. The engine has a slightly louder idle, too. I brought it into my local shop and the mechanic said there wasn't anything wrong with the car and he even drove it around and couldn't replicate the engine feel (he did not drive it on the highway). Something is definitely wrong with my car and it sounds like it is the same problem atomic is having. Do you have some additional insight into what you think is wrong with our cars?