So Fix it

Catalytic converters, also called "cats," absorb exhaust heat, and should, ideally, be as close as possible to the exhaust manifold for emissions compliance. This placement varies by make and model and can have a significant impact on performance.

The Y-Pipe

V-type engines often use y-shaped pieces of tubing to join the cylinder banks exhaust streams before entering into the converter. Converters are often bolted right to the back of this Y-pipe.

Direct Connection

Many manufacturers, such as Honda and Toyota, are becoming known for bolting the catalytic converters right to the exhaust manifold outlet, with nothing in between.

Down Tubes

Most turbocharged engines use a down tube, which is a smooth piece of tubing that allows a turbos exhaust flow to move away smoothly, before encountering the restrictive cat.

Oxygen Sensor

All new vehicles have an oxygen (O2) sensor somewhere between the exhaust manifold and cat. This works in conjunction with an after-cat O2 sensor to notify the engine control computer of any converter malfunction.

Exhaust Brakes

Large diesel trucks often have a large valve in between the cat and manifold, known as an exhaust or "Jacobs" brake. When closed, these valves create back pressure in the engine and allow a driver to control downhill acceleration without using the foot brake.

When working correctly, a catalytic converter cleans up the pollution that stems from your vehicles exhaust. The life expectancy of this part is well above 90,000 miles. However, because some issues can affect this estimate, its wise to test the converter for problems that could shorten its life.

Map Sensor

One way to test the efficiency of a catalytic converter is by disconnecting its MAP sensor. Doing this is supposed to make the converters temperature go up, which indicates no trouble. If the temperature remains the same, the catalyst has likely gone bad. It should also be kept in mind that an error code will occur once the MAP sensor is disconnected.

Plug Wire

By undoing and grounding a plug wire, you can create an overflow of hydrocarbons within the vehicles exhaust pipe. If the temperature goes up drastically, the converter is fine. This test should should not be run for more than two minutes because of the risk that it could damage the converter.

Exhaust Analyzer

An exhaust analyzer can also be used to check the performance of a catalytic converter to ensure that it reaches its life expectancy. This equipment can notify you if emissions levels are too high by taking readings at the exhaust pipe. An exhaust analyzer costs between $2,000 and $6,000.

When working correctly, a catalytic converter cleans up the pollution that stems from your vehicles exhaust. The life expectancy of this part is well above 90,000 miles. However, because some issues can affect this estimate, its wise to test the converter for problems that could shorten its life.

Map Sensor

One way to test the efficiency of a catalytic converter is by disconnecting its MAP sensor. Doing this is supposed to make the converters temperature go up, which indicates no trouble. If the temperature remains the same, the catalyst has likely gone bad. It should also be kept in mind that an error code will occur once the MAP sensor is disconnected.

Plug Wire

By undoing and grounding a plug wire, you can create an overflow of hydrocarbons within the vehicles exhaust pipe. If the temperature goes up drastically, the converter is fine. This test should should not be run for more than two minutes because of the risk that it could damage the converter.

Exhaust Analyzer

An exhaust analyzer can also be used to check the performance of a catalytic converter to ensure that it reaches its life expectancy. This equipment can notify you if emissions levels are too high by taking readings at the exhaust pipe. An exhaust analyzer costs between $2,000 and $6,000.

The catalytic converter reduces smog emissions by converting harmful emissions from your engine into less dangerous gases. Like any other part on your car, there will come a time when the catalytic converter will need to be replaced either because it is broken and has holes in it, or it just gets clogged up. The project is not difficult, and the entire process will take about an hour to an hour and a half to complete.

Instructions

1

Park the car on a level surface and set the parking brake.

2

Place wheel chocks behind the rear wheels.

3

Raise the car with an automobile jack and place a jack stand under the car at the frame rail. Position the jack stand as close as possible to the frame.

4

Remove the bolts from the front and back end of the catalytic converter with the proper size socket and a ratchet.

5

Remove the catalytic converter from the exhaust system by twisting it and tapping the ends with a rubber mallet.

6

Install the new catalytic converter in place of the old one and secure it with the bolts hand-tight.

7

Tighten all of the bolts with the proper size socket and ratchet.

8

Remove the jack stand and lower the car to the ground with the jack.

Problems with the catalytic converter on your Mercedes, or any vehicle for that matter, are often more difficult to deal with than most drivers realize because it is illegal to tamper with a catalytic converter in any way. This means it is illegal to attempt to fix your Mercedes catalytic converter by any means other than having an approved certified mechanic replace it.



There are both federal and state laws governing the removal and replacement of catalytic converters on vehicles. The noise your catalytic converter is making indicates a problem that may cause your Mercedes to fail an emissions test or land you a number of federal fines from the Environmental Protection Agency if not handled properly. It is only legal to remove it if the noise is affecting its function.

Instructions

1

Check the warranty. Your Mercedes may not be covered by the federally mandated Environmental Protection Agency warranty. Federal law emissions warranty specifies that if your car was manufactured before 1996, the catalytic converter is still under warranty only if the car has less than 50,000 miles on it. If the car was manufactured after 1996, the car is legally required to have more than 80,000 miles on it or be more than eight years old to be out of warranty.

Some Mercedes vehicles have documented issues with the catalytic converters. Mercedes reached a settlement with the EPA to extend the emissions warranties on these vehicles.

2

Take your Mercedes to the dealership, or a mechanic who regularly handles these cars, and have the catalytic converter tested. You will need to go to a mechanic who is familiar with the cars exhaust system requirements and has access to original equipment manufacturer, or OEM, exhaust parts. The converter used to replace your Mercedes converter must be identical to the original Mercedes catalytic converter.

If your car is still covered by the federal warranty, it will need to be taken to the Mercedes dealership.

3

Have the mechanic thoroughly document the problem with the converter, then, if necessary, replace it with an identical new converter. Documentation of the problem is a legal requirement if the converter needs to be replaced.

Since tampering with converters is illegal, your noisy converter will probably be replaced. If the converter is still functioning, the mechanic is not legally allowed to remove it.

4

Make sure the mechanic also fills out a warranty card as required by federal law. Save a copy of everything for your records in case of emissions inspection problems at a later date.

Practically every car sold in the United States since the mid 1970s has been equipped with a catalytic converter. These exhaust system components reduce the amount of harmful gases that are released into the atmosphere as byproducts of an internal combustion engine. Some say that a cars performance will improve after the cat (as they are sometimes called) is removed, but the basis for this claim is not backed up by any authority. Heres why you need a catalytic converter on your car.

The facts

Catalytic converters are required equipment for all gas and diesel powered cars on the road today. You cant buy a car that does not have one. Removing the catalytic converter from your car is in violation of the federally mandated Clean Air Act, and may also be in violation of state law as well. If you remove the cat, you will fail the emissions test when your car is next inspected. If you drive a car that has on board diagnostics, removing the converter will cause your "Check Engine" light to come on.

Function

The catalytic converter removes hydrocarbons (unburned fuel), carbon monoxide (CO) and oxides of nitrogen (NOX) from the exhaust before it reaches the muffler. There are two main types of catalytic converters: Two-way and three-way. Two way converters, which were the first to be put into general use, remove only the hydrocarbons and CO.

How they work

Catalytic converters essentially just burn the remaining hydrocarbons, CO and NOX to create harmless CO2, water and nitrogen. As temperatures approach 1,400 Fahrenheit the catalyst found inside the converter (usually platinum, rhodium and/or palladium) helps the oxidization of the exhaust gases without undergoing any chemical change to itself.

Significance

The Clean Air Act of 1970 was passed to prevent the dangerous emissions of fossil fuel combustion from becoming a serious threat to the quality of life in this country. Hydrocarbon emissions can contribute to many illnesses, including the irritation of the throat, lung and the eyes. Oxides of nitrogen are a component of smog and they produce ozone, which is a smelly irritant of the eyes and respiratory system. Carbon monoxide is extremely toxic and can cause death if inhaled in large concentrations.

History

After a catalytic muffler that was developed in the late fifties suffered failures due to lead additives in the gasoline, the first catalytic converters were created in 1975 by John Mooney and Carl Keith. These were two-way converters, and it wasnt until 1981 that the three-way catalytic converter was introduced.

Catalytic converters use exhaust heat trapped in a matrix of ceramic plate and precious metals to change exhaust gases chemical composition to a more benign form. Quick-moving gases might sometimes lack the opportunity to catalyze fully, which may require two or more converters.

Converter Function

Converters contain a honeycomb-like ceramic matrix with thousands of tiny passages. Exhaust flows through these passages, combining with the platinum, rhodium, palladium and cesium on the passage walls to add or subtract nitrogen or oxygen atoms. This gain or loss converts the toxic molecules in the exhaust into more benign forms.

Emissions Requirements

Different countries and unions have different emissions requirements and require different catalytic converters. The European Union disallows the use of nickel in converters but permits copper (which the United States does not). Most large car manufacturers offer several variations on the same chassis to market all over the world. Using more than one converter allows the manufacturer to meet local emissions standards while using the same basic chassis worldwide.

Modularity

Not all car manufacturers produce their own catalytic converters; many converters are outsourced from specialty catalytic converter manufacturers. Because most cars come with a number of different engine options, manufacturers may need to mix and match different converters to meet emissions requirements for a particular engine-chassis combination.

Removing the catalytic converter is not often required on your Jeep wrangler, but if you need to do it the process only takes a few minutes to complete. New converters are available though the dealer and many parts stores. They do not often go bad, but debris under the truck can damage the case or body of the converter.

Instructions

1

Raise the front of your Jeep with a jack. Position a set of jack stands under the front axle housing and lower the jack until the Jeep is resting securely on the jack stands.

2

Locate the catalytic converter under the truck. It is in the exhaust system just in front of the muffler and just behind the exhaust down pipe. Find the flange at the front of the converter with the two mounting bolts that secure it.

3

Remove the mounting bolts from the front flange with a ratchet and socket then separate the front pipe from the catalytic converter. Move to the back of the converter and locate the exhaust clamp that secures the catalytic converter to the muffler.

4

Remove the two mounting nuts from the clamp and separate the catalytic converter from the muffler by pulling the converter forward. Twisting the converter as you pull it will often help to free it from the pipe.

5

Remove the converter from under the truck.

Kids in the United States who reach driving age today probably dont remember acid rain and smog alerts. Those problems still exist, but their frequency and intensity have been mitigated, due in part to the catalytic converter, a clever little device developed by French engineer Eugene Houdry. He identified a growing problem in the smog heyday of the 1950s, but his invention wouldnt become standard equipment in most U.S. autos until the 1970s. Catalytic converters achieve their results efficiently with minimal power loss in todays cleaner-burning engines, but they can become clogged, or "poisoned," and that requires immediate attention.

What Is a Catalyst?

Catalytic converters are made up of a substrate, usually a ceramic honeycomb that maximizes exposed surface area, and a metal catalyst like platinum, rhodium or palladium that reacts with exhaust contaminants. Unburned hydrocarbons (HC), carbon monoxide (CO) and nitrogen oxide gas (NOx) are the big three baddies that the catalytic converter eliminates. Signs that your converter may be failing include sluggish throttle response, stalling at high temperature or a persistent sulfur smell coming from the tailpipe.

Poisons

The service life for most OEM converters exceeds 100,000 miles, so if your lower-mileage cars exhaust contains higher-than-accepted levels of HC and CO, the converter is fouled due to a problem elsewhere. There are contaminants that "poison" the reactive surface of the honeycomb. Lead is a converter killer, and while it was banned in gasoline in the 1970s, it is still found in some engine additives. Phosphorous and silicone are culprits also. Phosphorous is found in motor oil and can find its way to the converter if your engine is drawing oil into the combustion chamber. Silicone comes mainly from a leak that causes coolant to burn in the engine and exit to the exhaust systems. Both of these are engine problems that ruin the converter, not converter problems that ruin the engine.

Antidotes

A simple Internet search returns a host of products that promise to clean your catalytic converter. Some of these are temporary fixes designed to fool emissions-testing equipment. That gets you exactly nowhere in terms of fixing your vehicle. The consensus among mechanics is that you dont clean a catalytic converter--you replace it. Magical additives will cost you money, delay the inevitable and divert your attention from the real problem, which could be as severe as a failing head gasket that leaks coolant into the engine. Let that one go for a while, and youll be replacing your entire head at a cost of thousands. The bottom line is to be aware of the messages your car is sending. If your converter is indeed bad, either it has reached the end of its useful life or it is failing prematurely due to another engine problem. Dont get cute. It will cause you headaches down the road.

The Good News

One thing people never do is ask the mechanic to show them their old part when something has been replaced in their cars, which mechanics are required to do by law. This protects consumers against fraud. In the case of the catalytic converter, however, it can also net you some money. You own the failed converter, so youre entitled to take it with you and sell it for scrap. Its full of precious metals, so selling it to a scrap yard can help defray some of your repair costs. Also, the EPA mandates that warranties of up to 8 years and 80,000 miles be given on certain exhaust components. If your problem is the result of a defect, and your converter has failed earlier than it should, your repair cost could be covered under warranty.

Catalytic converters help dilute toxic chemicals that are pushed out of your car through the exhaust. While these converters last years and thousands of miles, there are ways to burn out your converter. This isnt something you want to do. To avoid burnout, consider the causes of catalytic converter failure, and have your car checked by a mechanic according to the manufacturers instructions.

Instructions

1

Drive your car with a malfunctioning oxygen sensor. This can cause thermal failure, which means that excess raw fuels are making their way, in large quantities, to your catalytic converter.

2

Drive around in a car that has a starter or engine that misfires. This can also cause thermal failure of the catalytic converter.

3

Drive around in a car with old spark plugs that are prone to misfiring. This too can cause burnout.

The 2004 Chevy Trailblazer base model came with a 4.2-liter inline six-cylinder engine and a four-speed automatic transmission. Your catalytic converter is located between the exhaust manifold and the muffler. A faulty catalytic converter can result in poor performance and higher emissions levels that will cause you to fail an emissions test. Replacing your catalytic converter is a straightforward task, but the transmission mount has to be removed because of the length of the catalytic converter assembly.

Instructions

Removal

1

Park the vehicle on a level surface and set the parking brake. Lift the front of the vehicle into the air with a floor jack and place jack stands under the front frame rails. Lower the vehicle until it rests securely on the jack stands. Allow the engine and exhaust to cool completely before continuing.

2

Position yourself under the vehicle so that you can clearly view the catalytic converter and its connection to the exhaust manifold. Locate the front oxygen sensor that is positioned just after the first flange and disconnect the pigtail from the wiring harness. Follow the catalytic converter piping after the converter to find the rear oxygen sensor. Disconnect the rear oxygen sensor pigtail from the wiring harness.

3

Place the oxygen sensor socket over the front oxygen sensor so that the pig tail extends through the slotted portion of the socket. Rotate the sensor counterclockwise with a ratchet to remove the sensor from the exhaust. Apply heat with a propane torch around the base of the sensor, if it is difficult to remove. Repeat for the rear oxygen sensor and label each one accordingly; they are not interchangeable and must be installed in the same position.

4

Place one jack stand at the rear and one under the front of the converter assembly, and elevate them until they make contact with the converter assembly. Remove the nuts securing the converter assembly to the exhaust manifold with a ratchet and socket. Remove the nuts securing the converter assembly to the rear muffler pipe.

5

Place a floor jack under the transmission and place a small block of wood on the jack arm. Raise the jack until the wood makes contact with the case of the transmission, but do not apply any upward force. Examine the transmission support that runs between the two frame rails to find the two center access holes. Remove the bolts securing the transmission mount to the transmission support with a socket and ratchet.

6

Remove the bolts securing the transmission support to the frame rails. Lower the transmission support from the vehicle and set it aside. Remove the bolts securing the transmission mount to the base of the transmission. Remove the catalytic converter and transmission mount from under the vehicle.

7

Pry the rubber hangers from the old catalytic converter assembly with a pry bar and set them aside. Set the transmission mount aside, with the rubber hangers attached.

Installation

8

Examine the rubber hangers for any damage or wear and replace as necessary. Install the transmission mount, with the rubber hanger bracket attached, to the transmission. Install the mounting bolts and tighten to 48 foot-pounds with a torque wrench.

9

Set the catalytic converter assembly onto the jack stands so that the flanges at both ends meet up with the exhaust manifold and muffler assembly. Lift the catalytic converter assembly as necessary and install the rubber hangers at the transmission mount to the metal hangers on the converter assembly.

10

Lift the transmission support into place between the frame rails and install the retaining bolts. Install the transmission mount to transmission support nuts through the access holes and tighten to 35 foot-pounds.

11

Install a new gasket at the front and rear of the converter assembly. Slide the converter assembly rear flange over the studs for the muffler pipe. Install the rear mounting nuts hand tight. Install the front converter flange to the exhaust manifold and install the mounting nuts hand tight. Tighten the mounting nuts for both flanges one turn at a time until they are tightened to 33 foot-pounds.

12

Remove the jack stands from under the converter assembly. Clean the oxygen sensor threads with a wire brush and apply copper anti-seize to the threads. Install the both oxygen sensors to the converter assembly until hand tight. Tighten both sensors to 30 foot-pounds with a torque wrench and oxygen sensor socket. Plug the oxygen sensor pigtails to their respective wire harness connectors.

13

Lift the front of the vehicle off the jack stands and remove the jack stands from under the vehicle. Lower the vehicle to the ground and remove the floor jack.

The catalytic converter is part of a vehicles exhaust system and serves to reduce the amount of toxic gases emitted into the atmosphere. These surprisingly simple components have served to dramatically reduce the amount of vehicle emissions produced over the past few decades. Today, they are installed on all factory-produced vehicles sold in the United States.

History

The Engelhard Corporation invented the first production-ready catalytic converter in 1973. A couple years later, the Environmental Protection Agency introduced more stringent regulations relating to vehicle emissions. Confronted with these new requirements, auto manufacturers quickly embraced the new earth-friendly product. The 1975 vehicle model year was the first time that the catalytic converter came pre-installed on new cars.

Effects

The first catalytic converters on the road were known as 2-way catalytic converters. Cars with such technology are capable of converting hazardous carbon monoxide to harmless carbon dioxide. They also break down toxic hydrocarbons into carbon dioxide and water. In 1981, 3-way catalytic converters became commonplace. Cars with this newer technology are also capable of reducing nitrogen oxides to regular nitrogen and oxygen.

Function

The catalytic converter converts toxic gases to harmless gases via a platinum-iridium catalyst. As the hydrocarbons and carbon monoxide pass through this catalyst, the gases are oxidized. This causes them to break down into less toxic elements. Nitrogen oxides require a separate process, known as reduction, to eliminate toxicity.

Considerations

The catalytic converter is typically situated below the front passenger seat, between the engine and the rear exhaust. In order to function properly, the combustion chamber must be fed the correct ratio of gasoline to oxygen. If too much oxygen or gasoline is introduced, excessive hydrocarbons and other toxic gases will be produced. These extra particles make it hard for the catalytic converter to keep up with the inefficiency of the engine. To eliminate such a scenario, most modern-day vehicles feature fuel injection and oxygen sensors to monitor the oxygen-to-gas ratio entering the combustion chamber.

Potential

Though catalytic converters have been integral in reducing vehicle emissions, there is still more that can be done. The biggest downside to catalytic converters is that they require a great deal of heat to function properly. This heat is generated by the engine, but it takes several minutes after you turn your car on before the catalytic converter becomes effective. Currently, engineers are tinkering with ways to speed up the heating process so that vehicle emissions are cleaned by the catalytic converter during these first minutes of vehicle operation.

The catalytic converter neutralizes some of the poisonous gases from the exhaust of internal combustion engines common in most modern automobiles. The catalytic converter on the Ford Escape is engineered to work with the Escapes specific engine and exhaust system. In the event a catalytic converter replacement is necessary on an Escape, be sure to purchase an exact replacement for the existing unit. Failure to use the proper replacement catalytic converter will lead to problems with the emissions system.

Instructions

1

Be sure the vehicle is cold and slide under the passenger side. Bring along the wire coat hanger, socket set, box wrenches and replacement catalytic converter.

2

Wrap the coat hanger around the exhaust pipe behind the catalytic converter and up through the frame to keep the pipe suspended.

3

Use the socket set and box wrenches to unbolt the fasteners in the front and rear flanges of the existing catalytic converter. Set the fasteners aside and put the old catalytic converter on the ground, out of the way.

4

Position the new catalytic converter between the collector pipe and exhaust pipe and reinstall the bolts into the front and rear flanges with the socket set and wrenches.

5

Remove the coat hanger from the frame and exhaust pipe and slide out.

In the 1970s, the catalytic converter was first introduced to control pollutants on cars and trucks. In 1976, the catalytic converter was made mandatory on all vehicles in the United States. The catalytic converter -- also caller a "cat" -- is responsible for removing unburned fuel from the vehicles exhaust. The catalytic converter typically fails when the catalyst material inside falls apart and clogs the converter. This clogging typically causes a very rough-running condition and sometimes causes stalling. Replacing the catalytic converter on a 1991 Geo Storm is relatively straightforward.

Instructions

1

Raise the front of the vehicle, using the floor jack. Support the vehicle by placing the jack beneath a secure part of the vehicle, like the sub-frame, and lowering the Storm until its weight is held by the stands.

2

Crawl beneath the vehicle, behind the front drivers-side wheel, until you reach the exhaust system. Locate the catalytic converter, the muffler-like component under the front seats.

3

Loosen and remove the nuts holding the front portion of the converter to the exhaust, using a ratchet and socket. If the nuts are frozen due to rust, use the propane torch to heat them up and try loosening them again. Push the converter towards the rear of the vehicle until the converter is clear of the studs holding it to the exhaust, then pull the converter down.

4

Loosen and remove the nuts holding the rear portion of the converter to the exhaust, using a ratchet and socket. If the nuts are frozen, use the propane torch to heat them up and try loosening them again. Pull the converter towards the front of the vehicle and off the exhaust system. Make certain to remove both the front and rear gasket from the exhaust pipes.

5

Place the new gaskets on the exhaust pipes, and use the studs on the pipes to hold the gaskets while installing the converter.

6

Place the front and rear of the catalytic converter on the exhaust pipe studs and hand-tighten the nuts on the studs. Make certain the "flow" arrow on the converter is pointing towards the rear of the exhaust.

7

Tighten the nuts on the converter to 32 foot-pounds, using the torque wrench and a socket.

8

Raise the Storm off of the jack stands, using the floor jack. Pull the stands from under the vehicle and lower it to the ground.

The catalytic converters in your Lexus LS400 are three-way converters that lower exhaust emissions through a chemical reaction between the exhaust gas and the substrate in the converter. This type of converter features the reduction capabilities of a reduction converter to lower oxides of nitrogen (NOx) and the oxidation capabilities of an oxidation converter to lower carbon monoxide (CO), carbon dioxide (CO2) and unburned hydrocarbons. Replacement catalytic converters in the Lexus LS400 come installed in an exhaust pipe assembly making replacement easier.

Instructions

1

Apply the parking brake and set wheel chocks behind the rear wheels. Raise and support the front of the Lexus using a floor jack and jack stands positioned under the front sub-frame. Lower the car onto the stands slowly so that the weight of the car is supported evenly by the jack stands. Remove the floor jack.

2

Allow the exhaust system to cool completely. The catalytic converters on the LS400 operate at a high temperature (over 600 degrees Fahrenheit) and can cause severe burns if not allowed to cool sufficiently prior to working on the system.

3

Spray the attaching bolts on the converter with a liberal coating of penetrating oil and allow it to sit for a few minutes. Remove the two rear mounting bolts that attach each of the converters to the exhaust system using a 13mm socket and ratchet to turn the bolt while holding the 15mm nut with a wrench. Pry the exhaust system back away from the converter and pull the exhaust downward.

4

Remove the three 13mm nuts that attach the converter to the exhaust manifold and pull the converter off the manifold studs. Use a new exhaust gasket between the converter and manifold. Bolt in the new converter, leaving the nuts loose so the converter can be moved slightly while lining up the rest of the exhaust system.

5

Raise the exhaust system and pry it back until it can be slipped onto the converter. Place a new gasket between the converters and the exhaust system. Install and tighten all of the nuts and bolts securely.

Catalytic converters are used in almost every modern internal combustion engine (gasoline or diesel) to filter toxic elements out of the engine exhaust. This mainly works by using a catalyst such as platinum or rhodium to chemically bond oxygen to the toxic chemicals, thus rendering them harmless and keeping them from being released into the atmosphere. Catalytic converters can be damaged by coolant leaks and overheating, and are sometimes stolen for the precious metals they contain, and since most countries require their use by law, they must be replaced immediately. They have a front inlet pipe and a rear outlet pipe, which can look similar. It is critical to identify which pipe is which before installation.

Instructions

1

Look up proper catalytic converter to buy for your make and model of car in a parts guide or at an auto shop, where it will have part catalogs for your car. The catalytic converter you purchase will be made specifically to fit your car.

2

Consult a diagram of your cars exhaust system once you have purchased the new converter, so that you can see where the converter needs to be installed. Note the shape of the converter and compare it to the diagram. This will tell you which pipe should face forward and which should face backwards. The forward-facing pipe is the inlet, and the rear-facing pipe is the outlet.

3

Mark the inlet and outlet on the new catalytic converter with a piece of chalk or a pencil so that, when you remove the old converter and get ready to install the new, you will immediately know which pipe goes forward (inlet) and which faces back (outlet).

Removing the catalytic converter from your Nissan Pathfinder allows for the replacement of it without having to replace other parts of the exhaust system. The converter is designed to reduce harmful emission or cases out the tailpipe of your Nissan, and if it is not working correctly, it needs to be replaced. A plugged converter may become very hot and often will cause the engine to run rough as well as producing an extremely unpleasant odor from the tailpipe.

Instructions

1

Place a jack under the front of your Pathfinder and raise it off the ground. Position a set jack stands under the front suspension to support the truck, then remove the jack for now.

2

Locate the catalytic converter from under the truck. It is in the exhaust system just below the drivers feet. Remove the two bolts in the rear flange that hold the exhaust pipe to the rear flange of the converter using a wrench.

3

Move to the front flange of the catalytic converter and remove the three retaining bolts with a wrench. Lower the catalytic converter and remove it from under the truck.

4

Raise a new catalytic converter into position and align the mounting flanges with the flanges on the exhaust pipes. Install the three front mounting bolts into the flange and tighten them with a wrench. Install the two mounting bolts into the rear flange and tighten them with a wrench.

5

Position the jack under the front of your Pathfinder and raise it off the jack stands. Remove the jack stands, then lower the Pathfinder to the ground.

Subaru Motors has employed multiple catalytic converters on its vehicles for many years now. Because the engine compartments are small and since the catalysts need heat to operate effectively, Subaru designed smaller converters and integrated them into the exhaust pipes--rather then employ a single, larger converter as most cars did at one time.

The Structure and Design

Many converters on Subarus begin at a front Y-pipe that bolts to both sides of the engine. In some newer applications, a third or fourth smaller converter is also integrated into the construction of the pipe. It is not uncommon to see yet another converter downstream integrated in the construction of an intermediate pipe. With so many converters, one of them is bound to need replacement at some point.

The walls of the shell on the Subaru converters are designed thin in order to reduce the resistance of exhaust gases. While this benefits the performance of the engine, it compromises the structural durability of the shell. In addition, since the converters are often integrated into the construction of the Y, or intermediate exhaust pipes, the pipe extensions can fail, requiring the replacement of the entire pipe and converter assembly.

Another more slightly annoying feature Subaru owners discover about the exhaust system on their vehicles are heat shield rattles. Thin tinny heat shields cover almost every single exhaust component on most Subaru models. These heat shields are susceptible to exposure and can break loose from connections and create annoying rattles while driving.

Cost

Because of the integration of the pipe and converter assemblies, Subaru converters are very expensive. The front Y-pipe assemblies can cost twice as much money to replace as the rear converter assembly. Many owners not savvy enough to do the work, will have to dish out money for labor installation as well.

While there are many quality aftermarket catalytic converter manufacturers these days, you can price the converters and pay less than half what the Subaru dealer will be asking. Finding a local repair station to install it for you will still save you money in the long run.

Although much cheaper, universal converters are not always an option when it comes to a Subaru. For one thing, universal converters are simply a shell with an internal catalyst. They need to be welded into the system are attached by clamps and sleeves. Because of the awkward angles and the small size of the Subaru converters--especially in the front Y-pipe--finding the right size and then welding it into the existing pipe without compromising how it needs to bolt to the engine and the remaining exhaust system is very difficult.

Internal Break Down

Subaru vehicles generally run well, and catalytic converters rarely fail unless something causes the damage. Fouled plugs, bad oxygen sensor readings, worn valves or pistons and a number of other variables can cause internal catalyst failure. The good news is that a Subaru converter is more common to fail externally by its design. The bad news is, if you dont take care of your Subaru and it causes damage to one or more of the converters, you now have a bigger problem. Buying and replacing the converters will be expensive enough. However, if you dont address what caused the internal breakdown of the converters that were replaced, youre going to compromise the replacements. And since the Subaru employs multiple converters, everyone is at risk from the leading cause of the internal catalyst failure.

Automotive enthusiasts use a straight catalytic converter, also known as a catless pipe, as a substitute for a conventional catalytic converter. This modification allows an engine to gain more power by eliminating back pressure.

Characteristics

A straight catalytic converter is an aluminized metal or stainless steel pipe, which varies in length and width depending on the vehicle. Automotive specialists use a catless pipe to determine whether a conventional catalytic converter is defective.

Function

As part of the engines exhaust system, a catalytic converter changes harmful emissions to carbon dioxide and water. Replacing a catalytic converter permanently with a catless pipe causes release of pollutants into the environment.

Significance

Because of their effects on the environment, straight catalytic converters are illegal. Instead of using a straight catalytic converter to enhance your cars performance, you can use exhaust headers and a free-flow cat system, an option that is safe and environmentally friendly.