Exhaust Manifold Replacement
What is an exhaust manifold?
The exhaust manifold is located between the engine cylinder head and catalytic converter. It collects exhaust gas as it leaves the cylinder head.
How does the exhaust manifold work?
As the engine pumps hot exhaust gases out of the cylinder head, the exhaust manifold collects it, building pressure.
Some exhaust manifolds are designed to store the extreme heat caused by the still-burning exhaust gases leaving the individual cylinders. This helps burn any residual fuel in the exhaust before the gas is sent to the next emission device, the catalytic converter.
When the exhaust manifold gaskets are leaking, you will hear a ticking or tapping noise, especially when the engine is cold. The noise may partially or totally disappear when the engine is warmed up.
What are the symptoms related to a bad exhaust manifold?
If the exhaust manifold gets corroded to the point of cracking, you'll hear a tapping sound. Other possible symptoms include black smoke from the exhaust when you accelerate and a lit check engine light.
If the muffler and exhaust pipe are hanging down, it can place additional strain on the exhaust manifold and cause its gasket to leak.
» LEARN MORE: Exhaust manifold symptoms
Can I drive with an exhaust manifold problem?
No, driving a vehicle with a leak in the exhaust manifold is not recommended. It can ruin fuel mileage, cause you to fail a smog inspection, ruin the catalytic converter and cause damage to the exhaust valves.
How often do exhaust manifolds need to be replaced?
Most exhaust manifolds last the lifetime of the engine. But problems do occur, and the likelihood of replacement is based on age rather than mileage. Hot engine temperatures from imbalanced air-fuel ratios will cause leaks in manifolds at any mileage.
How are exhaust manifold issues diagnosed?
Identifying an exhaust manifold leak can be very easy if you hear ticking and can smell exhaust — but minor leaks can be tricky. Ordinarily, the vehicle will be raised and the exhaust manifold will be inspected for signs of leaks, such as black marks and nearby burned components. If there are no signs, the exhaust may be smoke tested or plugged to help diagnose it.
An exhaust leak can have an effect on the fuel mixture and cause the Check Engine Light to come on. The exhaust leak should be repaired before replacing any other parts related to an incorrect fuel mixture.
We do not recommend resurfacing a warped exhaust manifold, as the manifold will be prone to warping and cracking.
How is an exhaust manifold replaced?
The manifold retaining hardware and old gasket will be removed, and all touching surfaces should be cleaned thoroughly. If the manufacturer specifies sealant, it is applied to the gasket; otherwise, the gasket is placed on the exhaust studs.
The new exhaust manifold will slide in place on the gasket, and the technician will torque the retaining fasteners to factory specification.