Toyota 17150-31010 Left Exhaust Manifold Sub-Assembly

Remove the six nuts that secure the exhaust manifold and then remove the exhaust manifold itself.

The catalytic converter is an emission control device added to the exhaust system to reduce pollutants from the exhaust gas stream. There are two types of converters: the oxidation catalyst, which reduces hydrocarbon (HC) and carbon monoxide (CO) levels by adding oxygen to the exhaust stream, and the reduction catalyst, which lowers oxides of nitrogen (NOx) levels by removing oxygen from the exhaust gases. These two types are combined into a three-way catalyst that reduces all three pollutants.

Use a scraper to remove all traces of old gasket material and carbon deposits from the manifolds and cylinder head mating surfaces. If the gasket was leaking, use a precision straightedge to check the manifolds for warpage and compare your readings. They can be resurfaced by a machine shop, if necessary.