Q: Just bought a used Forester that started rattling when I'm not accelerating and the wheel is straight. Any ideas on what it could be?

Hey there. The most common source of rattles on Subaru’s are the exhaust heat shields. They can rattle under all sorts of random circumstances. Whenever you turn, accelerate, let off the gas or brake, the motor experiences torque that is dampened by the engine mounts so the passengers won’t feel these vibrations. This torquing will affect the exhaust as much as any other component on the car. Checking for exhaust shield rattles is fairly simple. Use a soft mallet hammer to tap on the shields to see if it rattles. If it does, repairing this is more challenging than locating it. It’s a creative process that can only be decided in person. Of course, you will need to get under that car to access all of the shields.

Other than the exhaust shields, it could be a dust shield on the brakes or a sway bar end link. Both of these are far less common as determined by your description of your symptoms. If it is a sway bar end link, it will rattle most often when you go over bumps. If it is the brake dust shield, you will need to remove the wheel to see if the shield is loose.

If you need further help having this done, a certified professional from YourMechanic can come to your car’s location to diagnose the rattling noise so that this can be corrected.