catalyst

Assessing the technical condition of the purchased car, we often forget to check the performance of the catalytic converter. Meanwhile, there are many unscrupulous sellers offering cars with damaged or no catalytic converters.

Assessing the technical condition of the purchased car, we often forget to check the performance of the catalytic converter. Meanwhile, there are many unscrupulous sellers offering cars with damaged or no catalytic converters. If during the technical inspection of the car it turns out that this equipment is defective, the car will not be allowed to operate.

There is no comprehensive diagnostics of the state of the catalyst possible on our own, we should take advantage by qualified mechanics. Photo by Robert Quiatek

The catalyst is a vehicle equipment, the condition of which is difficult to diagnose on your own. The device itself is hard to see, it is located under the car, usually hidden behind the body. However, when buying a used car, it is worth taking some time to inspect this element of the car, as it is usually very expensive to repair. The first step may be to check if the catalytic converter is actually installed in the vehicle. However, you must be logged into the channel to do so. It happens that in some cars a piece of tube is inserted instead of a catalytic converter. You do not need to be an experienced mechanic to see such a "modification" at a glance. Of course, the absence of a catalyst does not exclude the possibility of its subsequent assembly, but we will have to take into account the costs, which usually range from a few hundred to more than 2 zł.

Check the condition of the catalytic converter!

Useful control

Catalyst damage is most easily detected by measuring the level of exhaust toxicity, explains Wojciech Kulesza, a licensed PZMot appraiser. - Symptoms of its inoperability are usually noticeable during the operation of the car. Loss of power, loud engine noise, or starting problems can be signs that the catalytic converter is not fully functional.

For proper operation, a strictly defined composition of the fuel-air mixture is required. The optimum ratio of air to gasoline is 14,75:1. Only computer-controlled injection equipment can provide such precisely measured doses of the mixture, so catalysts are better suited for cars equipped with fuel injection than with a carburetor. An important function is also performed by the lambda probe located in the exhaust system behind the catalyst. It analyzes the composition of the exhaust gases and sends signals to the injection control computer. If the catalytic converter is damaged, it is difficult to see with the naked eye. However, the control of exhaust gases coming out of the exhaust pipe will tell us a lot. The most important factor is the percentage of carbon monoxide (CO) in the exhaust gases. In a car without a catalytic converter or with a damaged catalyst, it ranges from 1,5 to about 4 percent. An efficient catalyst reduces this ratio to about 0,03% or even slightly lower.

The content of other compounds (nitrogen oxides, hydrocarbons and carbon dioxide) is a consequence of the amount of CO. An inspection carried out at the diagnostic station will reveal any irregularities that appear, and the trained eye of a mechanic will notice any mechanical damage.

“When buying a used car, it is also worth asking the seller if the equipment has been changed before,” says Wojciech Kulesza, a licensed PZMot appraiser. - Modern catalysts are more durable, but most manufacturers recommend replacing them after 120-150 thousand kilometers. True, catalysts can last up to 250 kilometers unscathed, but when deciding to buy a car with high mileage on the meter, one must take into account that the catalyst may soon need to be replaced due to wear.

Important rules

Be careful with fuel - even the smallest amount of leaded gasoline can permanently destroy the catalytic converter. It's easy to make a mistake, especially when you refuel from a canister.

Do not try to start the car using the "pride" method.

Try to use proven gas stations where the quality of fuel is good. Contaminated and low-quality fuel leads to the melting of the catalytic liner due to the high operating temperature. The correct operating temperature for a catalyst is around 600°C, with contaminated fuel it can reach 900°C.

Check the condition of the spark plugs regularly. The absence of a spark in one of the cylinders leads to unburned gasoline entering the exhaust system, fouling the catalyst.

It can be damaged if it hits a stone, curb, etc.

It is impractical to quickly cool the catalyst, which happens, for example, when driving into a deep puddle.

Check before you buy

Wojciech Kulesza, licensed PZMot appraiser

- Before buying a used car, it is worth checking what the exhaust pipe looks like. If it is very dusty or covered in soot, this is a sure sign that the exhaust system, especially the catalytic converter, may be failing. It's also pretty easy to check if the catalytic converter has been changed recently, but this usually requires the car to go into the channel. The new equipment will draw attention with its fresh appearance and shiny metal sheet, so it is relatively easy to match the seller's assurances with reality. We will also check the catalyst for signs of mechanical damage. Any cracks or bends may indicate that it has been hit, and its ceramic insert may crack.