Help with Low RPM Metallic Rattle (Video)

I'm glad you've said something. I believe I have the same sound (which is obvious in the car, but hard to record) and it too started intermittently and has progressively become constant at low RPMS. I've contemplated mounting a camera in the engine compartment when driving to try and capture the noise better. However, my rattle seems to be coming more from the drivers side and usually only makes the noise while the inverter engine appears to be part of acceleration. When the window is rolled down and I'm near a building, i can definitely hear it louder. My initial thought was vibration at that engine speed was causing the exhaust shields to rattle, but there doesn't seem to be any broken or loose attachment points anywhere. Another thought was the brake dust shield, but flicking/vibrating that doesn't seem to produce a similar metallic sound. I was just waiting to post something until i had a better recording.

 

I hear similar, off-and-on. It occurs in a narrow zone of the acceleration spectrum: a little more or less pressure on the gas pedal and it goes away. I seem to recall someone narrowed it down to a bracket for a small diameter coolant hose, at the front/right corner of the engine bay. The hose breaks at a joint, one side has a hose clamp, the other does not. Anyway, they thought it was that bracket rattling.

Found a pic:

 

Yeah, me too. Since mine is a Lexus ct, that bracket is slightly different on mine. I too tried to move it and was pretty solid as well.

I will break down and try and get a microphone mounted under the hood over the weekend and see if I can’t get a better recording and/or location


iPhone ?

 

Loose heat shield perhaps?

Posted via the PriusChat mobile app.

 

Mine wiggles but doesn't make any noise.

Disclaimer- this reply may not apply in all situations.

 

I would check the heat shields and exhaust bracket...
I've had both loose on a 2010 with 280K miles...

Posted via the PriusChat mobile app.

 

Sounds to me like the center exhaust bracket is cracked. I had the same sound. It's under the middle of the car and the bracket breaks off the exhaust pipe that it is welded to. I'd check there first.

 

Had a similar sound in my 2010 w/ 75k miles.

It was a piece of the exhaust shielding. I used a rivet gun to put the shield back in place and the rattle went away.

I highly suggest putting the car on ramps and with it in park slowly press on the gas & extremely slowly back off the gas to find the exact RPMs you get the sound for. If you can then have someone in the car press on the gas with you under the car finding the rattle doesn't take but a couple seconds.

I can definitely relate to how frustrating this is. Good news is most of the time if the rattle isn't the entire exhaust system falling off (not likely) it isn't a big deal.

 

I have the mid-exhaust bracket weld problem. What's the best solution?

It's visible under the car. You don't need to lift the car even, just look underneath and reach with a 2- or 3-foot piece of wood -- hold it against the bracket while someone is revving to reproduce the rattle to see if that dampens it. Looks like this:

Mid-exhaust Bracket 1 by milksheikh posted Oct 5, 2020 at 4:55 PM

Mid-exhaust Bracket 2 by milksheikh posted Oct 5, 2020 at 4:55 PM

 

Hands down the funkiest wheel chocks lol.

 

Hi Ethan/all. Were you ever able to solve this noise? I'm getting the exact same problem and it doesn't seem to be either the coolant hose nor the exhaust system.

Managed to mount a phone under the car and get a recording

 

Update for those that find this thread in the future. It was a loose/rusted mesh spacer on the heat shield for the exhaust/cat. The bolt was still very tight, but the steel mesh that's meant to hold the heat shield firm was all deteriorated, allowing the heat shield to rattle at a certain RPM.

There's no way to replace the spacer from what I can tell, we had to snip the shield to remove it.

Pics here

 

I've had this rattle too and thought I finally found the source after your tip to check this bracket. It was separated completely but even after removing it a rattle is still there. I guess I'll have to get under it and check the heat shields more thoroughly.