If you hear a tinny, buzzing rattle from under your car, especially at idle or when you first pull out on a cold morning, there’s a good chance it’s a heat shield. It’s one of the most common noises we hear about at our shop, and the good news is that it’s usually one of the easier ones to fix.

Heat shields are thin sheets of metal that sit between your exhaust and the rest of the car. Your exhaust gets extremely hot, and those shields keep that heat away from the floor of the car, the fuel tank, wiring and anything else nearby. They’re held in place by small bolts, clips or welds, and over the years those mounting points rust and loosen. Once a shield comes loose, it vibrates against the exhaust pipe and makes that annoying rattle.

You’ll often notice it most on cool fall mornings, because metal shrinks a little when it’s cold and the gaps get bigger. As everything warms up, the noise may quiet down or disappear, which is why so many people put off having it checked.

Some people are tempted to just pull a loose heat shield off and be done with it. We’d steer you away from that. The shield is there for a reason, and without it the heat from your exhaust can damage parts of the car above it. In most cases we can secure the shield with a new clamp or bracket instead of replacing it.

Not every rattle is a heat shield, of course. A broken exhaust hanger, a loose clamp, or pieces breaking apart inside a catalytic converter or muffler can sound similar. That’s why it’s worth having someone get the car up on a lift and find the exact source.

Here’s a fall safety tip while we’re talking about exhaust heat. Your catalytic converter runs hot enough to ignite dry leaves and grass. Avoid parking over leaf piles or tall dry grass, whether that’s in your yard, at a ballgame or at a fall get-together out in the county.

If something under your car is rattling, bring it to Exhaust Plus Auto Center. Exhaust work has been our specialty in Columbia since 2001. Call (931) 388-8411 or stop by 102 W 5th St, Monday through Friday from 8 to 5.