alexkidd

I have two severe rattle issues that I can not figure out. The Lexus dealer can't seem to either. The first one which is the worse, only happens when its 5C or cooler. It is a constant knocking noise coming from the passenger front door area (I think). It happens when going over bumpy roads. I can only compare it to a marble in a cup kind of sound. It is driving me insane because it is loud and can happen like 50 times in a minute. The 2nd one happens less often but its coming from somewhere in the rear of the vehicle. It happens mostly when the car flexes a bit like turning into a parking lot and going over the small curb. It is a loud metallic knock. It sounds like it could even be coming from the roof in the back. These sounds are hard to narrow down when you are driving. I am hoping someone has had the same issues. Thanks!

Solara350

In my case, the 1st noise front passenger door over a bump it was my BATTERY bracket loose, i tighten it with a 10mm socket, noise gone right away. Similar noise for other member, they said it was their Hood Bump Stop, tighten it down or something that helps.

2nd one, not the Lexus IS , but i heard it from my old Toyota Solara and a friend's 2014 Acura ILX, yep i heard it from the rear Roof ,heard it from friend ILX also and i asked him he said ya that weird knock noise, i thought someone throws rock at his car ! i'm so lazy to dismantle the Sunroof and the roof cover.

You need to bring it to a alignment Shop and check it out while you there and explain to the mechanic. i hate bring it to Dealership because i CANNOT talk to the Mechanic directly, some of the girls in front desk don't know what we talking about that drives me nut, they good at TALK ABOUT LOVE/MONEY but not good at TALK ABOUT CAR !

Sasnuke

If you think the first one is coming from the passenger door, look at the check strap to see if it needs some lube.
The check strap (or whatever you want to call it) is in the middle of the front of the door between the hinges...it controls how far the door opens, or specifically, how far it can open.
When the door is closed, the check strap is inside the door, so if it's dry it may cause a noise. So white grease, or any kind of grease, and applied around the strap will stop the noise, if that's what is causing it.
You could use some vaseline just as a test to see if that's it.

SilenceIX

I m pretty sure I have both of these rattles.(same car) the passenger side one sounds exactly how you describe. its so sensitive that I can replicate it by steering hard back and forth with the car..... I've been trying to hunt it down for months, and its single handedly making me hate my car. if I do eventually find it, I will report back. unfortunate how unacceptably bad the rattles are in this car....