Low-pitch grind in reverse and during regen braking

Hi all!

I believe [fear] the problem here is the transaxle and it's either got some metal that needs to to be removed, or it's kaput entirely. This would be the second replacement in 6 months, so not thrilled about that.

Anyway, the symptoms:

1. During braking, from about 40mpg down to about 15mpg, there is a subtle but noticeable grinding noise coming from the engine compartment, transaxle area
2. If in Neutral, there is no grinding (MGs are disengaged in Neutral)
3. When in reverse, any acceleration makes a squeeky/grindy noise
4. It's not the brake actuator (it was also recently replaced and makes a healthy noise when re-compressing after brake usage)
5. It's not the brake pads/rotors--they are fairly new, installed myself, and there is never a peep when in neutral and only using the conventional brakes at any degree of pressure
6. There was a inverter/mg coolant pump failure shortly before this started. It was only driven a few miles after the failure in order to get home. I replaced it with a brand new one at home and it worked like a champ and is still working great.
7. I've checked the fluids, they're fine

So, I'm hoping someone will say "oh no it's not the transaxle it's only this small $30 part you can replace in 20 minutes" but I accept any confirmations, albeit begrudgingly, that it is a transaxle issue. What I would like to know is thoughts on whether it is some sort of bearing failure or maybe just some metals cycling around in one of the MGs which could be removed with a few flushes.

Your thoughts are appreciated!

(2006 2nd Gen Prius with 164k miles. Had the transaxle replaced about five months ago at GreenTec Auto)

 

Hi Bisco,

I was never told how many miles were on the replacement they put in. We agreed to a warranty of 18months for labor only as they could not warranty a salvage yard part. Unfortunately, the part is quoted as $1200 and the labor is $800, so the crux of the job was in parts which I would have to pay for again. A used transaxle doesn't cost $1200 at the yard, but I suppose that cost includes removal and transport fees as well. In any case, I now know a Prius mechanic who says he replaces the entire engine and transaxle at once for no more than $1500, so it would almost be a better value to do that.

I simply don't want the transaxle to be a problem again, it's a little disheartening to have repeated repair needs back to back. Transaxle, then brake actuator, then coolant pump. I got a good deal buying the car, so I figure I'm at the break even point now, so spending a bit more isn't the end of the world. However, it is starting to feel like a money pit and I don't want that to be the case. It's supposed to save money, but currently we're in the negative.

 

Thanks JC. Now that I think of it, I believe they did warranty the part. In any case, I'm hoping to not even need to go down that road. I will do a trans fluid change and see if I can get anything out of there.