Your Altima's exhaust does a lot: it breaks down pollutants, quiets the engine, moves exhaust gases away from the cabin, and even increases power. When something goes wrong, it can keep your car form performing at its best, and can even pose a serious safety hazard. Here's what you need to know to find and fix issues with your car's exhaust system, from the exhaust manifolds to the tailpipes.
How It Works When the burnt fuel and air are pushed out of the engine, they enter the exhaust manifold. This part uses a set of tubes to collect the exhaust gases and merge them into a single outlet. This lets the exhaust pulses pull gases out of the cylinders, which helps to increase power. There's on manifold on each cylinder bank: if you have a four cylinder, there will be one manifold. If you have a V6, there will be two manifolds.
Next, the exhaust passes through a catalytic converter. The number of converters and their position varies depending on the model you have and the engine. Older Altimas have a small “pre-cat” converter next to the exhaust manifolds and a full size converter further down the exhaust stream, while newer models will have full size converters next to the manifolds.
After this, the exhaust goes through a down pipe. This has a flex pipe, which acts as a flexible joint that absorbs vibrations from the engine. One or more oxygen sensors are used to let the ECU monitor the exhaust and ensure the converters correctly. The catalyst in a catalytic converter reacts with the exhaust gases, burning any remaining fuel and breaking down pollutants into their less harmful components. A certain amount of oxygen is needed for this reaction to take place, and that oxygen should be removed by the reaction. Oxygen sensors may be located on the exhaust manifolds, on the downpipe, or on both parts.
This is followed by more pipe going toward the rear of the vehicle. Along this pipe are mufflers which bounce around the exhaust, absorbing shock waves to quiet the exhaust note and smooth it out. Recent models send the exhaust through a single tube that ends in a Y-pipe. This pipe splits the exhaust flow into two sections, with each section feeding into a muffler. Some exhausts finish with tips that dress up the rear end.
The exhaust system attaches to the car using rubber mounts that go over hangers. This lets the components swing back and forth as the vehicle passes over bumps. Sections of the exhaust are connected using bolts and gaskets to create a tight seal.
Since the exhaust is hot, heat shields are placed in strategic locations to control temperatures in the engine bay and cabin. There are shields over the exhaust manifolds and catalytic converters, as well as a few other key points.
What's “Right” and “Left” on a V6? If you're looking for a V6 exhaust manifold, picking one for the side you need can be a little confusing. Right and left on an engine is determined by their orientation to the front of the motor. On a transverse V6, the front of the engine is facing the passenger side of the car, so the side closest to the radiator is the right side, while the side closest to the firewall is the left side.
California vs. Federal Emissions Systems The California Air Resource Board (CARB) issues emissions standards going above and beyond those required by federal law. Some Altimas have emissions systems built specifically to meet CARB's stricter requirements, and that means some exhaust components will be different. Since we share a border, it's pretty common to come across these cars here in Arizona.
How can you tell which emissions system was fitted to your Altima? Open the hood and look for the emissions system label. This label will be located on the radiator support, next to one of the strut towers, or on the hood. If the phrase “this vehicle conforms to U.S. EPA and State of California regulations” is on the label, your car was built to meet California emissions standards. Parts designed for these cars are labeled “CAL” or “California,” while parts for non-California cars are labeled “Federal.” If there is no label, the part will work with cars with either emissions system.
What Causes Problems With Exhaust Systems on Altimas? Heat shields expand and shrink as their temperature changes, and this can slowly loosen the bolts that hold them on. Most exhaust rattles on these cars are caused by loose or missing bolts on these pieces.
If the exhaust is bent from an impact, it can break the seal between components and gaskets. Even the tiniest separation can let exhaust gases through, burning out the gasket and turning a small leak into a big one. Larger impacts can bend pipes and split the casings on mufflers.
Catalytic converters usually last the life of the vehicle, but a poor running engine can overload the converter with extra fuel or oil entering the exhaust. This can clog the catalyst or cause it to shatter. If the converter fails, make sure any engine issues are addressed before fitting a replacement.
Oxygen sensors will wear out eventually, and when they do, the ECU can't mix fuel correctly. Fuel economy will drop, emissions will go up, and the engine will run rough. This should switch on the check engine light and deliver the appropriate code when using an OBDII scanner.
Dry rot is an inevitability in the desert, which can really take its toll on rubber hangers. Eventually, they'll split, letting the exhaust hang low or fall off entirely.
Where to Get Replacement Parts for Your Altima's Exhaust If you want to fix your exhaust the right way, visit CoulterPartsCenter.com. We sell only Original Equipment Manufacturer (OEM) parts, which are made and warrantied by Nissan. This means they fit your Altima's mounts perfectly for easy installation and they provide the same level of performance and durability as the parts installed on your vehicle at the factory. We make finding the right part simple by letting you search by part numbers and keywords like “muffler,” and you can filter those results by your model or VIN, so you only see parts that are compatible with your car. Have questions? Don't see what you need? Call or email us to talk to our staff of factory-trained parts personnel.