I bought this car back in October. Within a day it started rattling. The rattle is intense and can be felt in the pedals and gearshift. No mechanic can figure out what it is. It has an aftermarket exhaust but everything seems tight and secure. I have replaced the passenger side motor mount, the torque strut mount and the transmission mount under the battery. A mechanic also went under the car and tightened down almost everything he could find. The problem has definitely improved but it’s still there. The rattle usually occurs when I’m driving at high speeds, usually around 60mph. As I accelerate to speed it’s smooth, but when I take my foot off the gas and place it back in lightly to coast the noise begins. Sometimes it works itself out, but other times I’ll park and still hear a light, almost squeaky type of rattle. It feels like something is just loose and touching where it shouldn’t, but it’s driving me crazy! Are there any other motor mounts that might be the cause? Does it just sound like something’s loose?
[Rattle noise 2005 vw jetta with aftermarket exhaust - YouTube]
Find a mechanic with a set of “chassis ears” which will enable him to locate the source of the noise. And get your tires balanced.
I just had 4 new tires put on and balanced a couple weeks ago. It didn’t make any difference with the noise
I wonder if you have something loose in the exhaust system. I’m thinking something like a heat shield, or maybe something inside of a muffler or catalytic converter.
What clued me in was your mention of the noise “settling in” at highway speeds, which means a certain constant RPM. I had this happen to me once; it turned out to be something broken/loose inside the muffler. A new muffler fixed the problem.
Doesn’t mean they were balanced correctly, or that a weight didn’t fall off. Have them balanced again at another shop.
My Honda Civic has some double-wall exhaust pipe. I bottomed out and stressed the pipe. It had a vibration/droning noise that an exhaust shop traced to the pipe between the exhaust manifold and the catalytic converter. They replaced it and the noise has never returned.