Toyota 17150-31250 Left Exhaust Manifold Sub-Assembly

The catalytic converter is an emission control device in the exhaust system designed to reduce pollutants, with two main types, oxidation catalysts which reduce the content of hydrocarbon and carbon monoxide by supplying oxygen, and reduction catalysts to reduce the oxides of nitrogen by taking away oxygen. V6 models have four converters; they are upstream catalysts located in the exhaust manifolds, and downstream converters located in the front exhaust pipes V8 models have three converters, one of which being a downstream converter situated directly behind the Y-pipe. Checking for a faulty converter needs specific tools and thus if problems are being thinking to exist, one should involve a dealer or an accredited center. Daily and weekly inspection schedules are required for leakage, corrosion and any signs ofphysical injury; if it is plugged the vacuum gauge comes in handy. For replacement, the process includes lifting of the vehicle off the ground with a car lift securely, disconnecting the oxygen sensor connectors, application of a penetrant to the flange nuts of the exhaust, and removing the downstream catalyst separately or the whole assembly of the front exhaust pipe for both. Disassembly is done in a topsy-turvy manner starting with the head followed closely by the gaskets and fasteners; in this process new gaskets and nuts are used while tightening all nuts to the recommended tightness.

Installation is the reverse of removal. Be sure to use a new gasket and install it with the oval-shaped protruding tip facing in the correct direction: for the left (driver's side) manifold, the tip must face to the rear; for the right manifold, it must face to the front.

Disconnect the cable from the negative battery terminal.