Why is my exhaust making a blowing or roaring noise?
An exhaust blowing noise — a throaty roar, ticking, or hissing that gets louder when accelerating — is caused by a leak in the exhaust system. The most common failure points are the joints between sections (especially the front pipe to manifold joint), the lambda sensor boss, or holes in the silencer box. Beyond the noise, an exhaust leak can allow carbon monoxide into the cabin, so it is important to get it checked promptly.
Likely causes
Exhaust manifold crack or blown gasket
Causes a ticking/tapping noise from the engine bay that is louder when cold; very common on high-mileage engines
Front pipe or downpipe hole or joint failure
Section between manifold and catalytic converter often corrodes or the clamp joint blows
Silencer / box hole or rust-through
Middle or rear silencer boxes corrode and develop holes — typically a loud drone under load
Lambda sensor boss leak
Threads around the oxygen sensor can strip or the sensor can work loose, causing a hissing leak
Repairs you may need
Typical cost range: £50–£500 — Exhaust joint weld or patch: £50–150. Silencer box: £100–250. Full exhaust replacement: £200–500+. Manifold gasket: £150–350.
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