Since 1992, the Nissan Altima has been a reliable commuter car and a sporty alternative to the Honda Accord and the Toyota Camry. No Altima can deliver consistent performance on the road without a well-maintained exhaust system. Here's a quick breakdown of the Altima exhaust parts that you'll probably need to replace at some point.
An exhaust manifold is a metal coupling that channels exhaust gases from the cylinders into the exhaust pipe. On an Altima, it looks like a hand with several fingers that's bolted to the rear of the engine. Manifolds ensure that your exhaust system maintains the proper internal pressure required for reliable performance.
There are two primary reasons why an exhaust manifold will eventually fail: rust and metal fatigue. Corrosion is often the culprit when your manifold springs a leak. Furthermore, manifolds have to deal with a lot of heat on a regular basis. Exhaust gases induce significant metal expansion and contraction that will inevitably fracture the unit.
One sign that an exhaust manifold is bad is a pronounced rattling or rumbling sound coming from underneath the central console. If the noise isn't the result of a loose heat shield, you'll probably see a CEL indicator on the instrument cluster. Swapping out the manifold requires a jack, some stands, a ratchet and a little elbow grease.
Catalytic converters take nitrogen-rich exhaust gases and chemically alter them so that they're less harmful to the environment. Generally speaking, catalytic converters are found between the exhaust manifold and the muffler. They tend to be fairly expensive due to their complex construction and the rare earth metals like rhodium and platinum found inside.
Over time, catalytic converters become clogged with a variety of combustion by-products. Since they're subjected to so much heat, their internal parts eventually succumb to the thermal stress and break down. Catalytic converters don't typically fail overnight. Rather, you'll usually observe a steady decline in engine performance over the course of months or even years.
Common signs of a failing catalytic converter include recurring CELs and rattling noises coming from the vehicle's undercarriage. Other indicators of a bad catalytic converter include lousy fuel economy and sluggish acceleration. Swapping out a catalytic converter can be as simple as loosening some bolts or as complicated as welding in a new part.
A muffler is a metal box found at the end of the exhaust that dampens sound. Without a muffler, your Altima would generate far greater noise when idling or accelerating. The muffler houses a resonator chamber and a set of perforated pipes that allow exhaust gases to exit the tailpipe in a controlled matter.
Like most exhaust parts, mufflers eventually fail due to rust, physical damage and heat stress. Due to expansion and contraction, internal baffles eventually crack or break loose. Likewise, the muffler's exterior will eventually spring leaks due to collisions with road debris and corrosion. In either case, a muffler loses the ability to effectively cancel sound.
A decent OEM Nissan muffler can be had for as little as $60 depending on your model year and trim level. Replacing a muffler is a simple matter of unbolting the old unit and fitting in a new part. You'll need a breaker bar, a set of sockets and a new gasket to complete the job.
Every modern vehicle uses a variety of oxygen sensors distributed throughout the exhaust system to monitor vehicle emissions. They look a bit like spark plugs and are screwed into sockets embedded in the tail pipes. O2 sensors send data to an Altima's ECU, which adjusts engine settings to achieve maximum fuel efficiency.
Oxygen sensors eventually become clogged with combustion by-products over time. Since a portion of the sensors are exposed to the elements, they tend to rust pretty quickly in moist environments. Failure to keep the engine in good shape by changing air filters and oil regularly will hasten an oxygen sensor's premature death.
If you notice that your Altima's fuel economy is slipping and you observe frequent check engine lights, oxygen sensors are likely culprits. A quality OEM O2 sensor can be had for as little as $40. To replace an oxygen sensor, you'd simply unscrew the old unit, substitute a new one and reconnect the wiring harness.
All exhaust system components are attached to each other using bolts and gaskets that ensure a tight seal. Gaskets are simply metal rings that fit around the ends of pipes. When you install a new muffler or catalytic converter, the gaskets are compressed as you tighten the flange bolts that secure the new hardware.
Like all metal components, gaskets experience a significant amount of expansion and contraction as the exhaust system heats up and cools down. While most gaskets hold up fairly well over time, they occasionally develop cracks that negatively impact exhaust system performance. Buying new gaskets is a must if you're swapping out a part like a muffler.
Common signs that one or more gaskets have failed include check engine lights, noticeable leaks under the vehicle and noisy exhaust. Fortunately, gaskets are fairly cheap and can cost as little as $10. Replacing a gasket almost always requires the use of a jack, jack stands or car ramps and a decent socket wrench set.
Altima owners are often surprised to discover that the exhaust system isn't firmly bolted to the body. It's actually suspended from the bottom of the vehicle using a series of mounting brackets that allow for a decent amount of movement. These brackets are typically a mixture of metal and rubber parts.
Mounting brackets or hangers aren't the sturdiest parts and can easily succumb to rust. What's more, rubber bushings tend to harden, crack and completely disintegrate over time. This usually results in a significant rattling noise coming from the exhaust. In extreme cases, the bolt holes that allow hangers to attach to the body rust away entirely.
You can tell that a mounting bracket is on its way out if it allows the exhaust assembly as a whole to sway to an unreasonable degree. Mounting brackets are extremely cheap and generally pretty easy to install. All you have to do is support the exhaust, unbolt the old hardware and replace it with new gear.
Major exhaust components like catalytic converters and mufflers always have a heat shield situated between themselves and the vehicle's body. A heat shield absorbs thermal energy from the exhaust system and radiates it safely. An Altima that's missing one or more exhaust heat shields is far more likely to suffer from fire and heat damage.
Heat shields are simply thin pieces of lightweight sheet metal that are held in place by simple bolts or clips. As such, they're especially vulnerable to rust and physical damage due to collisions with road debris. If you have to replace a muffler or catalytic converter, it's usually a good idea to install a new shield.
The most common indicator that your heat shield needs to be replaced is a persistent rattling noise coming from your exhaust. Quality OEM heat shields can cost anywhere from $40 to $80 depending on your specific exhaust layout. Be sure to properly support your Altima with sturdy jack stands if you're performing the replacement yourself.
The Right Exhaust Parts for Your Altima
If you want your exhaust system to deliver years of glitch-free performance, buying OEM Nissan parts is a must. At ProNissanParts.com, we take the guesswork out of locating the right exhaust parts for your Altima. Peruse our expansive inventory today to find the best gear available at the lowest prices on the web.