Fix It

A catalytic converter is an exhaust emissions device that is part of a vehicles exhaust system. In charge of lowering the exhaust emissions that exit a vehicles tail pipe, a catalytic converter can negatively impact vehicle performance if it goes bad or stops working properly. What follows is a brief list of the most common signs of a bad catalytic converter.

Reduced Exhaust Flow

A major sign of a plugged up and/or bad catalytic converter is reduced exhaust flow measured at the vehicle tail pipe. Engine exhaust must travel through a catalytic converter before exiting the tail pipe; a bad catalytic converter can block and/or impede exhaust flow.

Reduced Engine Power

If a bad catalytic converter seriously impedes the flow of a vehicles engine exhaust flow, reduced engine horsepower can occur. This is due to the increase in engine exhaust back pressure that results whenever engine exhaust flow is impeded and/or reduced.

Reduced Exhaust Pipe Temperature

It is common for a bad and/or plugged catalytic converter to cause abnormally low exhaust pipe temperatures on the backside of a catalytic converter. As engine exhaust exits an engine and travels down the exhaust system and through the catalytic converter, the exiting exhaust flow can be restricted enough to cause significantly reduced exhaust pipe temperatures between the catalytic converter and the tail pipe.

Increased Hydrocarbon Emissions

Catalytic converters work by reducing the levels of hydrocarbon emissions exiting a vehicles tail pipe. A bad catalytic converter can lose its emissions-lowering capabilities and cause an increase in exhaust hydrocarbon emissions, a condition that is normally picked up when a vehicle is undergoing a routine smog inspection.

Reduced Fuel Economy

Any obstruction and/or abnormality in a vehicles exhaust system has the potential to reduce vehicle gas mileage by creating exhaust back pressure within a vehicles engine. A bad catalytic converter can cause a reduction in vehicle fuel economy if it restricts the flow of engine exhaust to the point of causing a marked increase in engine exhaust back pressure.

The constant heating and cooling of your vehicles exhaust system, combined with moisture, will quickly cause the exhaust flange bolts to rust and seize. The rust has often progressed to the point that the threads of the exhaust flange bolts are unusable. To release the exhaust flange bolts, you will need to apply heat to remove the rust from the threads; and if the threads are beyond use, you will need to cut the bolts from the exhaust flange.

Instructions

1

Inspect the area around the exhaust flange bolts to make sure that there are no fuel lines or combustible materials within the area and clear any combustibles from the area underneath the vehicle.

2

Put on your leather work gloves and tinted safety glasses.

3

Place the fire extinguisher close to you in an unobstructed area so you can easily reach the extinguisher in case there is a fire.

4

Turn on the acetylene and ignite the torch with the striker. Turn on the oxygen and set the flame hot by increasing the oxygen until the inner bright blue flame is about 1/2 of an inch long.

5

Set the tip of the torch 6 to 8 inches away from the first exhaust flange bolt and heat the bolt until it has a dull orange glow then turn off the oxy-acetylene torch. Do not use the air trigger to heat the bolt faster.

6

Allow the exhaust flange bolt to cool and then place a socket that fits the bolt head onto the ratchet.

7

Slide the socket onto the nut located on the exhaust flange bolt and turn the ratchet handle counterclockwise to loosen the exhaust flange bolt. If the first nut will not loosen, proceed to the next step. If the bolt loosens, repeat the process with the rest of the exhaust flange bolts.

8

Reignite the oxy-acetylene torch, set the flame as described in Step 4 and place the tip of the torch 3 to 4 inches away from the head of the exhaust flange bolt.

9

Heat the bolt head until you see a bright orange glow emitting from the metal and then hit the air trigger to blow additional oxygen onto the bolt. You will see the bolt head melting and blowing toward the floor.

10

Turn off the oxy-acetylene torch and immediately strike the threaded side of the exhaust flange bolt with a hammer to remove the bolt from the exhaust flange. Repeat the procedure with each exhaust flange bolt to free the exhaust flange from the manifold.

11

Allow the bolts and molten metal to cool for at least 30 minutes before you leave the area to ensure that no combustible materials catch on fire.

12

Clean up and dispose of the cut exhaust flange bolts after they have cooled for one or two hours to reduce the chances of starting a fire in a garbage can.