Saturday, October 12, 2013
Installing an Exhaust on a Toyota Tacoma
The Muffler and Tailpipe Assembly
From the assembly line, the Toyota Tacoma comes with an inlet pipe, muffler and tailpipe all welded together as a single unit. It is common when replacing an exhaust system on the Toyota Tacoma, to deal with the replacement of this assembly. From the Toyota dealership, the same assembly would be installed, again welded together as a single unit. In the popular and more cost effective aftermarket exhaust replacement market, the system is usually broken up into two or three pieces. The muffler would stand alone or have the inlet pipe welded to it and the tailpipe would be a separate pipe attached to the muffler by a clamp.
Replacing the Exhaust
The muffler inlet pipe (in front of the muffler) is attached to the catalytic converter with a two-bolt flange. With the Tacoma on a car lift, (much easier than laying on the ground) the bolts are cut with an acetylene torch and the flange is separated. Any oxygen sensors present are detached and the original equipment exhaust is unhooked from any rubber hangers and removed from the undercarriage of the Tacoma. The system can be removed by dropping the inlet/muffler low and moving toward the front while wrangling the tailpipe over the rear axle. A simpler way is to cut the original system into pieces with the torch, but since its a stainless steel system, it requires a level of skill with the torch. The replacement involves attaching the inlet pipe or the muffler with the welded inlet (this usually depends on the overall length of the Tacoma measured at its wheelbase. The longer the wheelbase, the higher the probability of the inlet pipe being a separate component in the aftermarket world) to the catalytic converter with a gasket in between. The muffler is installed behind that (unless already attached to the inlet) with the tailpipe behind the muffler. The inlet pipe is the only flange connection and the other one(s) are connected with exhaust clamps. To finish, the oxygen sensor is restored into the new system.
The Converter and Front Pipe
The only other two components that comprise the remaining exhaust system are the catalytic converter and the front pipe. These are not commonly replaced as often as the muffler assembly. But at some point, as the Tacoma ages, these components will fail. The converter is flange-connected to the front pipe and to the inlet pipe of the muffler. The front pipe is flange-connected to the converter and then to the bottom of the manifold. Again, the presence of oxygen sensor(s) are dealt with. Overall, the exhaust system on the Tacoma is a fairly simple one. The front pipe is a dual chambered inlet from the manifold (with a three-bolt flange) that folds into a single double-walled chamber and attaches to the converter (with a two-bolt flange). The converter has a two-bolt flange on either side. New gaskets and new nuts and bolts are necessary to complete the replacement installation of either of these components.
The Oxygen Sensors
The oxygen sensors on the Toyota Tacoma are quite commonly the first introduction that a Tacoma driver encounters with his or her exhaust system. Unlike any other vehicle, Toyota trucks and SUVs often attach their oxygen sensors to the exhaust system with a small two-bolt flange and gasket. The portholes in the exhaust system has a manufactured inlet flange with two studs welded to it. The retaining nuts of the oxygen sensor deteriorate and allow the sensor to blow out of the porthole creating an exhaust leak. Re-tapping the studs and replacing the nuts are a common repair, but in some cases, the sensor itself needs to be replaced. The sensors are attached by a wire harness that is used to communicate to the computer of the vehicle. The sensors monitor the mixture of oxygen in the exhaust system and defer the information to the Powertrain control module (PCM) to make necessary adjustments. The wire harness of the oxygen sensor has a nearby outlet that simply can be unplugged for easy replacement. Some of the newer Tacomas require locating the downstream sensor (near the converter) to disassemble the floor molding of the passenger side door and reach under the carpet to the floorboard under the passenger seat to locate the plug.
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