Loud roaring exhaust noise

Symptoms

• Noticeably louder engine/exhaust sound than normal
• Roaring or droning noise, especially under acceleration
• May have started gradually or suddenly
• Could be paired with reduced fuel economy or a slight power loss

Likely causes

• CommonExhaust leak at a pipe joint or gasketAny gap in the system lets exhaust noise escape before being muffled.
• CommonRusted-through section of exhaust pipe or mufflerRust perforation is a very common cause, especially in areas with road salt.
• PossibleDamaged or missing muffler/resonatorPhysical damage from road debris or a low-clearance obstacle can crack or dislodge these components.
• PossibleCracked exhaust manifoldA crack near the engine causes a loud noise especially noticeable at idle and low RPM.
• PossibleStolen or removed catalytic converterA very sudden extremely loud roar, often noticed right when starting the car, can mean the converter itself is missing.

What to do

1. If the noise appeared very suddenly and is extremely loud, check underneath for an obvious gap where a section (possibly the catalytic converter) is missing.
2. Visually trace the exhaust system from the engine to the tailpipe for obvious holes, rust-through, or disconnected sections.
3. Listen near the engine (with it running, from a safe distance) for whether the loudest point is near the front (manifold) or further back.
4. Check for soot streaks around joints or the manifold, which indicate where exhaust is escaping.
5. Avoid driving further than necessary with a significant exhaust leak, since it's louder than legal in most areas and can let fumes enter the cabin.
6. Have a muffler or exhaust shop weld or clamp a repair for a rusted section, or replace the damaged component.
7. If a catalytic converter is missing, file a police report if theft is suspected and check with your insurance company.
8. Get a full exhaust inspection done, since one visible problem sometimes means other sections are also close to failing.

Tools and parts

• Flashlight

When to call a pro

A loud roaring exhaust should be inspected and repaired by a muffler or exhaust shop soon, both for noise and for the risk of fumes entering the cabin.

Safety