Symptoms
- Loud rumbling or roaring, especially at idle
- Noise gets louder when you press the gas
- Vibration felt through the pedals or floor
- Noise seems to come from underneath the car
Likely causes
- CommonRusted-through muffler or pipeExhaust pipes rust from the inside out and eventually perforate, especially on older cars.
- CommonBlown or loose exhaust gasketA gasket where pipes join the manifold or each other can blow out, causing a sharp leak noise.
- PossibleDisconnected or fallen pipe sectionA hanger can rust and drop a pipe section, breaking the seal at a joint.
- PossibleCracked manifoldA cracked exhaust manifold leaks right at the engine and is often loudest at idle.
- Less commonAftermarket or damaged mufflerImpact damage from a curb or pothole can crush or split a muffler.
What to do
- Listen for where the noise is loudest by walking around the car while it idles safely in park.
- Look underneath for a visibly hanging, disconnected, or rusted-through pipe section.
- Check for black soot streaks around joints and gaskets, which point to a leak location.
- Gently wiggle the exhaust system by hand (engine off, cool) to feel for loose sections.
- If a section is dragging or hanging, temporarily secure it away from the road with wire so it doesn't drag or fall, then drive carefully to a shop.
- Have a shop pressure-test or visually inspect the full exhaust run if you can't find the leak yourself.
Tools and parts
- Flashlight
- Jack and jack stands (optional, for a better look underneath)
Exhaust repair clamp or muffler patch kitSearch: “exhaust repair clamp kit”
Replacement muffler or exhaust gasketSearch: “muffler or exhaust gasket for [your car]”
When to call a pro
See a muffler or exhaust shop if you can't find the leak, if a pipe is dragging, or if the noise is very loud and constant, since a leak near the engine can also let harmful exhaust gases into the cabin.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.