Ticking noise from the exhaust manifold

Symptoms

• Ticking noise from the front/top of the engine near the exhaust manifold
• Often most noticeable right after starting, before the engine fully warms up
• May quiet down or change character once the exhaust fully heats up and expands
• Could be paired with a faint exhaust smell under the hood

Likely causes

• CommonExhaust manifold gasket leakA gasket that's beginning to fail lets small pulses of exhaust escape, producing a ticking sound.
• CommonCracked exhaust manifoldA crack, often at a bend or corner, opens slightly when cold and can close as things heat and expand.
• PossibleLoose exhaust manifold boltsBolts that have loosened over time can allow a small gap to open and close.
• PossibleManifold gasket surface warped from heat cyclingOver time and many heat cycles, the mating surfaces can warp slightly.
• PossibleUnrelated valve train ticking being mistaken for a manifold leakIt can be difficult to distinguish the two without a stethoscope.

What to do

1. Listen carefully right after a cold start, since manifold leaks are often most noticeable in the first minute or two.
2. Once the engine is cool (never touch a hot exhaust manifold), visually inspect for soot streaks radiating from a bolt or gasket seam, which indicates where exhaust is escaping.
3. Check exhaust manifold bolts for looseness if you're comfortable doing so, or have a mechanic check and re-torque them.
4. Have a mechanic use a stethoscope to distinguish manifold ticking from valve train noise, since they can sound similar.
5. Avoid ignoring a manifold leak, since exhaust fumes escaping in the engine bay can potentially find their way into the cabin through the ventilation system.
6. Have the gasket replaced if a leak is confirmed, which typically also involves re-torquing or replacing the manifold bolts.
7. Check for a cracked manifold if re-torquing bolts doesn't resolve the ticking, since a crack requires manifold replacement or welding repair.
8. Get this addressed in a reasonable timeframe, both for the noise and to prevent exhaust fumes from being present in the engine bay.

Tools and parts

• Flashlight

When to call a pro

A suspected exhaust manifold leak should be inspected and repaired by a mechanic, both to eliminate the noise and to prevent exhaust fumes from entering the cabin.

Safety