Right fender area RPM rattle/buzz - FIXED

jimpjorps · Jan 2, 2016

My Gen 3 developed this same rattle after a routine service a couple weeks ago. I assumed it was something in the cabin so I spent a while trying unsuccessfully to diagnose the rattle, but eventually I resigned myself to assuming it was either related to the cold weather or I had cracked the inside of the fender somehow. After coming across this thread, I popped the hood and found the same loose latch, and immediately zip-tied it up. Thanks for this tip!

dame3780 · Apr 25, 2016

lindguini said: ↑

I've been hunting a right front fender area rattle/buzz for a year on my 2013. My rattle/buzz is transmitted through the right front fender area and is directly related to engine RPM, usually making the most noise just after the engine turns on during the transition from electric-only mode under acceleration. It's most noticeable during acceleration from a stop when there's less road noise. The rattle/buzz noise is repeatable and can be modulated whenever accelerating through the initial electric-to-engine transition. It's clearly a mechanical resonance transmitted through the right front body area.

Searching back over many posts, it appeared that some people were able to reduce or eliminate a similar rattle/buzz by stuffing old towels/rags into the chassis and fender cavity just behind the right-hand side hood hinge. I tried this method but the rattle was still present (if not a bit muted, more on that in a second). There was also a Toyota Service Bulletin for early 2010-11 models that addressed a possible rattle from the right front fender due to a fender clip design problem, but vehicles after 2011 had the new clip from the factory so this shouldn't be the source of the rattle on later model years. I tried the stuffed-rag method, packing the "rabbit holes" with towel strips meticulously (thanks for the tutorial, phoenixgreg!). However, even after the cavities were fully stuffed, I found the rattle was essentially the same but not quite as loud. I concluded that the rags might be dampening the transmission of sound through the fender area but they were not actually addressing the cause of the vibration. I extracted all the rags using a long wire "tool" and determined that my rattle could be unrelated to the fender clip issue.

It was at that time that I remembered one lone post (somewhere on Priuschat) where someone had asked the dealer to fix the same rattle/buzz problem. The poster's photo of the fix showed that the dealer had installed some foam tape under the black plastic clip that secures the black rubber coolant return hose junction between the engine and the coolant tank mounted to the right fender area. Could it be that easy? This clip snaps into a metal bracket next to the right headlight and stares you in the face when you open the hood. It looked like a ridiculously simple solution that made sense the more I thought about it. So, I took a look at the clip on my car and noticed right away that the clip is very loose-fitting on the metal bracket. If you shake the hose back and forth, the clip rattles against the bracket. Considering that one end of the coolant return hose is mounted to the engine (which vibrates) and the other end is fixed to the coolant tank (fixed to chassis, no vibration) it made sense that if the rubber hose vibrates (resonates) under certain engine RPM, then the clip would rattle in the bracket, sending the rattle noise directly up the right fender and into the passenger compartment area. So, instead of using foam tape, I installed a black zip-tie to prevent the clip from moving on the bracket. Upon first test drive, the previous rattle/buzz is COMPLETELY GONE.

It's been three weeks of total, silent, acceleration bliss. Just to check this solution, I clipped off the zip tie and drove my daily commute again --the buzz was back and as loud as ever. I came home, reinstalled a new zip tie and the buzz is once again gone. That is a problem solved. What a pleasure to drive again without dreading the buzz at every acceleration. See photo below for the clip and my single zip tie installation. I'm sure you could use any number of methods to stop the clip from rattling. I chose the zip tie for convenience but I can understand why foam tape would work, as well, if stuffed into the bracket to prevent the clip from moving. I hope this works for others!
Click to expand...

Thank you for this post! You just saved my sanity. It's been 2 years with this rattle. I cannot say thank you enough. Seriously one of the most annoying sounds. I almost sold my car bc of it. I looked around the fender area yesterday and was pushing things, seeing what was loose. A rock fell from behind a plastic protector on inside pass fender. I was thinking...no way could that be it. I saved your post so I could check the clip. It was loose and had a lot of play in it. I zip tied it and no noise!! This really saved me. I could not deal with it anymore. My Prius has been misdiagnosed at numerous dealers over the last few years for this. No one could ever find it. Thanks again!

Kenny94945 · Apr 25, 2016

Awesome...
New 2016 v and this clip was loose on ours too.
First rattle...fixed (although I did not hear it).

Shaking the clip there was a clear rattle.
What I did was remove the clip and apply some thin strips of electrical tap on the top and side of the metal bracket then reinstalled the clip.
That clip is now solid with no rattle.
Thank you OP!

BumbleBee · Mar 24, 2017

Long Time lurker but Register today to say Thank you. This have been a nightmare since it started 2 month ago. It started small then it become a loud rattle. It was embarrassing driving friend around town turning up the volume hoping they don't notice. I Poked all over the dashboard, Glove Box and Pillar and could not recreated the sound when it was parked. Who Would have thought the noise came from a small clip near the headlight.

jdh81478 · Feb 5, 2019

I have a 2010 gen 3 and have been living with this noise for 3 plus years. Finally took some time while on paternity leave to pull off the entire dash only to find by process of elimination that it was actually emanating from outside the cabin. My wife and I swore the noise was coming from inside ! We’ll just tried this zip-tie trick and it seems to have reduced the rattling by 90% I’ll know for sure after I put the dash back together and do some more driving. Thanks lindguini ! And the lone poster who had originally posted the fix !

MARK A SLOO sloo · Mar 8, 2021

Thank you to all posters for the info in this thread. I quieted both rattles using the procedures described and my 2010 now drives like new again with $190k miles!

myPriusAcct · Aug 6, 2023

The zip tie on the coolant cable fixed my buzz as well.

My buzz was a little different. It started high in the eco rpm range, just before the power rpm range. It only happened with a cold engine and disappeared when everything warmed up.

Lived with it for years but it slowly got worse. Thank you for posting this fix.

Right fender area RPM rattle/buzz - FIXED

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Right fender area RPM rattle/buzz - FIXED

jimpjorps New Member

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MARK A SLOO sloo Junior Member

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