Car Doctor Q&A: Guessing About a Noise Isn’t Diagnosis

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When you spend good money with an automotive shop, you expect better diagnosis of an issue than just a guess. 

Q. I have a 2014 Jeep Grand Cherokee and there is a rattle coming from the back of the vehicle. The noise was driving my crazy until the weather got cold and then it sort of quieted down. When I first start driving I don’t really hear anything, then after a while the rattle comes back.

I took it into a shop and they looked it over and didn’t find anything. They suggested replacing the rear shocks, but even they said the shocks seem to be working ok. They admitted they were just guessing.

Any thoughts about this rattle?

A. If you have checked all the normal things such as the spare tire, jack and lug wrench and they are all tightly stowed, then it’s time to move on to the suspension.

The best lift/hoist to inspect suspension components in one that you drive on. That will keep the weight of the vehicle on the tires. This way if there is a worn bushing you will be able to see it.

Additionally look carefully for rust colored dust that builds up when components rust and become loose.

If you want to use technology to help, find a shop with a listening device called a Chassis-Ear, this can help with finding the noise. A Chassis-Ear is an electronic listening device that has several microphones you mount under the vehicle. Then you road test the vehicle and tune in on where the noise is coming from.

If we’re just guessing, I can do that just as easily over the internet and save you the money of having a shop do it. One characteristic issue with this vehicle is that the rear shock mounts have been known to be a problem. The mounts have a rubber bushing mounted in a steel bracket that can fail and allow the shock to rattle especially once everything warms up.

The shocks can be working fine, and the mounts are only about $20 each but if you are going to replace the shock mounts, it would be worth the extra expense to replace the shocks.

John Paul is public affairs manager for AAA Southern New England. A certified mechanic, Paul tests dozens of new cars each year and also hosts a radio show on AM 950 and 550.