Difference between revisions of "Catalytic Converter"

Revision as of 22:38, 3 August 2008

I found a good place online to get cats from this weekend (August 08) thought it might be useful for anyone looking to buy.

cats2go

Each cat available is shown with CGI image so you can match with the one fitted to your car I know the Gen 5's listed below are different shapes but the site only shows one shape for the gen 6 coupe and cabriolet (the "stubby" one) IIRC there is a cat varient for the gen 6 with a long tailpipe AFAIK this one isnt listed on the site. Heres the ones that are listed.

Gen 5:-

 CELICA 2.0 16 Valve Eng - 3-SGE   1989 1993
 CELICA 2.0 16 Valve GTi - !! Free Fitting Kit !! 1992 1994

Gen 6:-

 CELICA 1.8 STI !! Free Fitting Kit !! 1995 1999
 CELICA ST202 2.0 16 Valve DOHC GT. Cabrio. !! Free Fitting Kit !! 1994 1996
 CELICA ST202 2.0 16 Valve DOHC GT. Coupe. !! Free Fitting Kit !! 1994 1996

I'm asuming the prices may change so i wont post, I'd advise using the site to check for fitment.

Also heres an exerpt I found on a web site Here

Introduction Of Catalytic Converters

Catalytic converters on motor vehicles were introduced in the U.K. in the early 1990’s to cut down on air pollution caused by exhaust fumes. It was hoped that the use of catalytic converters on cars would improve the overall air quality, especially in big cities where smog can be a problem.

Catalytic converters also have other environmental and health benefits. They cut down the amount of the poisonous gas carbon monoxide leaving the exhaust pipe. Catalytic converters also cut down on the amount of nitrous oxides that enter the atmosphere. Nitrous oxides are the primary cause of smog and acid rain.

It should be remembered that while catalytic converters filter out the most harmful substances they still release gases that are harmful to the atmosphere, like carbon dioxide.

How Does It Work?

The catalytic converter usually consists of a honeycomb structured ceramic monolith, which is surrounded by matting. The matting holds the monolith securely in place and provides a cushion against road shock and vibration. This is all encased in a steel shell to provide further protection. Another option is a steel monolith, which is more durable. The steel monolith we supply has a texture similar to cotton wool.

The catalytic converter is situated in the exhaust pipe, usually close to the manifold. This is because the catalyst needs to reach a certain temperature before it starts to operate properly, so the closer it is to the engine the quicker it reaches operating temperature.

CO, HC and NO enter the catalyst

Carbon Monoxide (CO)

Hydrocarbons (HC)

Nitrous Oxide (NO)

CO2, H2O and N leave the catalyst as fumes

Carbon Dioxide (CO2)

Water (H2O)+(C02)

Nitrogen (N)

The monolith is coated with platinum, palladium and rhodium. These substances cause a chemical reaction to take place as the exhaust fumes pass through the monolith. The carbon monoxide is converted to carbon dioxide, the hydrocarbons are converted into water and carbon dioxide, and nitrous oxide is converted into nitrogen.

Advice For Fitters

Catalytic Converters can be extremely difficult to fit. The following advice may be of use when trying to fit your catalytic converter:

1. Don’t attempt to fit a catalytic converter unless you have experience in doing so. Catalytic converters are very expensive items and any mistake could damage it.

2. Never use exhaust paste in front of the catalytic converter.

3. Don’t hit the catalytic converter with a mallet or hammer to try and force it into place. Doing so may fracture the monolith and invalidate the warranty.

4. Use new fittings, such as gaskets or nuts and bolts wherever possible.

5. Always offer the cat to the car to see if it will fit. If you believe the catalytic converter would have to be altered to fit contact your point of purchase. You may have the wrong catalytic converter for your car. Any alterations made without our authorisation will invalidate the warranty.

Caring for the Cat

There are several things you can do to ensure your CAT has a long and healthy life:

1. When fitting the catalytic converter don’t use exhaust paste in front of the cat. When the exhaust paste hardens it can break off in chunks and destroy the monolith.

2. Always use the correct fuel for your car.

3. Never use a fuel additive without first reading the instructions to find out if it is suitable for use with a catalytic converter. If in doubt, consult the manufacturer of the additive.

4. Never attempt to bump or tow start your car. This causes unburned fuel to be injected into the cat, which makes the monolith overheat and melt.

5. Never tow anything that is too heavy for your vehicle to cope with. For example, an overloaded caravan will actually push a car along when it travels downhill. This sends unburned fuel into the exhaust system and can cause the monolith to melt down.

6. Have your car regularly serviced to your car manufacturers specifications. In particular make sure the engine is running properly. A poorly tuned engine can cause the monolith to break down or become covered in soot, which stops it working correctly.

7. Take care when driving through deep puddles, fords, or parking when there has been heavy snow. The cat operates at an extremely high temperature, and when it comes into contact with water or snow it cools down rapidly. The steel shell cools more rapidly than the monolith, and in extreme circumstances the monolith can be crushed as the steel shell contracts.

8. Don’t park your car over long grass or anything similar. As the cat operates at such a high temperature it can actually set the grass on fire!

9. Drive slowly over speed bumps or very bumpy roads to reduce the chance of the exhaust system being grounded. This could cause impact damage to the cat.

Warranty Information.

Although every effort is made to ensure a catalytic converters will not fail, sometimes a problem with the vehicle will cause them to break down. The following problems are NOT covered by a lot of companies warranty policies:

Road Damage

This is external damage caused to the catalytic converter by hitting solid objects in the road. i.e., speed bumps, large rocks etc.

Plugged Or Contaminated.

Plugged or contaminated catalytic converters are caused by using the wrong sort of fuel in your car. Using leaded or lead replacement fuel will plug up the monolith and cause it to stop working. A similar thing will happen if fuel additives are used that are not suitable for use with a catalytic converter.

Oil Fouled

This is caused by oil getting into the exhaust system and contaminating the catalytic converter. The most likely cause is a leaking gasket.

Melted/Broken Substrate

A monolith is usually broken when it is impacted by an object or when it suffers a sudden change in temperature. If the cat suffers road damage (See section on “Road Damage”) the monolith inside can be cracked due to it being crushed by the movement of the steel can.

The use of exhaust paste before the cat can also cause the monolith to break. When the exhaust paste has hardened small pellets can break away and shoot into the cat. The monolith will gradually be destroyed by these pellets and break down. The cat can also be destroyed by excessive engine vibration.

A rapid change of temperature can also break the monolith. (See number 7 in “Caring for your Catalytic Converter”)

The monolith can be melted when unburned fuel is injected into the cat. This can be caused by the car being tow or bump started, or if the car’s engine requires several turns before firing. More information on the causes of melting monoliths can be found in the section on “Overheating”.

Overheating

There are many problems that can cause a cat to overheat or fail. The most common cause is unburned fuel entering the cat. Also faulty spark plugs and leads will cause the engine to misfire and ruin the converter. The cat will also be ruined if the distributor timing is out.

Oxygen Sensor

An oxygen sensor collects and sends information to the Electronic Control Unit. This is used to control the air/fuel mix . If the oxygen sensor is faulty, or it has been contaminated with silicone from anti-freeze or sealant, the air/fuel mixture will not be corrected and excess fuel will enter the cat, causing it to overheat.

Fuel Injection Systems

If a fuel injector is leaking internally or dribbling fuel into the engine the converter may be damaged. The excess fuel will enter the exhaust system and cause the cat to overheat. Due to the varying fuel injector systems the proper manual should always be consulted when trying to diagnose a problem.

Map Sensors

Map Sensors tell the Electronic Control Unit the load on the engine and the amount of air entering it. If this sensor fails it causes a rich condition in the engine which can overheat the cat and cause it to fail.

Canister Purge Valve Control

This vacuum operated valve vents fuel vapour from the carburettor bowl to the charcoal canister. If the vacuum is breached the charcoal canister will flood, causing the air/fuel mixture to become very rich. This will cause the converter to overheat and eventually fail.

Noise

A cat should not be considered to be a silencer although it does have some silencing qualities. Noise can be caused by excessive fuel getting into the converter.