Exhaust Leak Symptoms: Manifold Leaks, Sounds and Safety

Common exhaust leak symptoms are a ticking or puffing noise that is often loudest on a cold start, a louder exhaust or a deeper rumble, an exhaust smell in or around the car, reduced power and fuel economy, a check engine light from upset oxygen sensor readings, and black soot marks around a joint. An exhaust leak can let carbon monoxide into the cabin, so any exhaust smell inside the car needs fixing right away.

Exhaust leak symptoms

• Ticking or tapping that speeds up with engine rpm, usually from the manifold
• Puffing, hissing or a louder, rougher exhaust note
• Exhaust or burning smell, especially when stopped; see burning smell from car
• Check engine light with oxygen sensor or lean codes such as P0171 or P0133
• Vibration felt in the pedal or floor
• Black soot streaks at a joint, gasket or crack

Exhaust manifold leak

Manifold leaks come from a cracked manifold, a failed gasket or broken studs and bolts, a common problem on many V8 trucks. They usually tick loudest when cold and quieter as the metal expands, and the sound rises when accelerating. A leak ahead of the oxygen sensor can draw in outside air, so the sensor reads lean and the engine computer adds fuel; see O2 sensor.

Exhaust leak vs lifter tick

Both tick with engine speed. A manifold leak is often loudest cold and may change with load; a lifter tick usually stays the same and comes from the top of the engine. Look for soot at the manifold first; see lifter tick and engine ticking noise.

How to find an exhaust leak

1. Listen with the engine cold, at idle and with light throttle.
2. Look for soot traces at joints, gaskets, flex pipes and hangers.
3. With the engine cold and running, carefully feel near joints with a hand held away from the pipe, or use a smoke test.
4. Check for rusted-through pipes and broken hangers underneath.

Is it safe to drive?

A small leak at the tailpipe end is mostly a noise problem, but any leak near the front of the car or under the cabin can let carbon monoxide in. Do not drive with exhaust fumes in the cabin, and fix leaks promptly.

Repair options

Replace failed gaskets, broken studs or cracked manifolds, and replace rusted pipes or flex sections. Upgrading after a repair? See cat-back exhaust, resonator vs muffler and titanium vs stainless exhaust.

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