Annoying metalic rattle

Every 2010 has a dozen or so rattles. I hope they do better with the gen IVs

 

Wow, I'm impressed with your ability to tear down the dash. I thought I was the only one! Anyway, someone here posted a hint that the metal tube that runs across the dash (a stabilizer and crash protection) was not correctly attached to the brackets on the right/left inner fender. The dealer discovered some bolts that had come loose that were transfering a rattle from one side to the other. As long as your dash is out, see if either of the brackets holding that metal tube is loose. I think the dealer added some better locking washers and that solved the member's problem.

On a separate note, do you get an airbag error when you drive your car without the dashplate on? As long as your this far down in the dash, when you put it back together, be sure to add some sticky-backed felt (black) to any plastic surfaces that come in contact with each other. That is one of the main problems on the '10s and '11s for ticks and rattles. I put some felt between where the main dashplate connects to the firewall and that seem to have helped too. Good luck...rattle-chasing is a real challenge on a Prius.

 

Nedim--if this rattle is also inside the car, just push around the area where you hear the noise, having a friend drive could also help here.

 

nedim, since it's a 2010, you might have the right fender clip problem most of us had. It almost sounds like a buzzing rattle when you accelarate and it's comes from the right A pillar or just under the small right front window? If so, reply and I'll post a link to my solution.

 

nedim, before trying my solution, take your car for a drive with the HSI on (in the MID area, the PWR/ECO/CHG display). Then, accelarate your car to the 3/4 mark or 1/2 way into the second ECO zone. Once there, back of the trottle a bit and accelarate again staying right around the 3/4 zone. If you hear the buzzing/rattle, you've got the defective fender clip problem.
I posted this solution years ago and my noise is gone for good. What I suggest is using small rags such as several worn out socks and keep packing them in the "rabbit holes" (see picture) to stop the vibrating clip. Be careful not to distort the fender area outside beneath the small front window. There are 2 "rabbit holes" - one beneath the small window and the insides of the A pillar itself. Both are visible with a bright flashlight with the hood up.
Right fender area RPM rattle/buzz - FIXED | PriusChat

 

I'm not sure anyone has taken a picture of the defective clip - and if your noise is not a "buzzing rattle" at certain RPMs, it could be some other problem. If you can get a passenger to listen right at the A pillar while you are at RPM, it would confirm it. Short of removing the fender, which is a huge job, I don't think there's another solution. Part of the rag-stuffing method is to prevent engine noise and vibration from getting to clip. I packed rags so you could actually see them from under the hood (picture).
Also, this is another similar problem/fix:
Right fender area RPM rattle/buzz - FIXED | PriusChat

 

I'm not really sure, but I think the clip holds the fender to the body. As to where it is exactly, I can only guess it's just below the small right front window (as you show in your diagram - circled). I just looked at the other end of that area by opening the passenger door and prodding just behind where the upper hinge meets the body. I see and was able to wiggle some piece of black plastic back there. I wonder if that is part of the problem?

 

just a thought, how about spraying expandable foam?