The last two blogs have been about air flow at high engine speed through variable valve timing( keeping the intake valve on longer @ higher speeds) The other blog was on precise relation & correlation between the valves and crankshaft through a timing belt.
Today I will talk about Catalytic Converters.
In the last 6 moths a number of customers have come into the workshop & Mannys Mechanical with the engine light on. Once scanned the dreaded fault code P0420 Catalyst system below threshold has been recorded. What does this mean? and why is it so expensive to fix?
What is a Catalytic Converter?
In 1986, Australia outlawed anti- knock agent Tetraethyl – Lead made it compulsory for cars to use Unleaded petrol. Also cars were fitted with catalytic converters in the exhaust system. A catalytic converter converts harmful unburnt fuel (hydrocarbons) into a inert gas.
A catalytic converter uses precious metals to react with the incoming exhaust gases in a ceramic monolith with a honeycomb structure.
The catalyst itself is most often a mix of precious metal. Platinum is the most active catalyst and is widely used, but is not suitable for all applications because of unwanted additional reactions and high cost. Palladium and rhodium are two other precious metals used. Rhodium is used as a reduction catalyst, palladium is used as an oxidation catalyst, and platinum is used both for reduction and oxidation. Cerium, iron, manganese, and nickel – this list pretty well explains the expensive metals used & hence the cost.
There are a few different catalytic converters – a two way & three way. For catalytic converters to be effective the temperature must be around 426celcius. Which is why they are usually incorporated in the exhaust manifold & this is also the reason why oxygen sensors also have heating elements.
The picture above shows Kamahl holding a brand new Catalytic Converter incorporated with engine pipes to suit a Subaru Outback $2698.00 – yet they sell on Ebay for $400.
Would I buy from Ebay?
Not in your life. You will be lucky to get 4 months before it fails again. Heaps of after- market cheap rubbish do not use the precious metals listed above to last.
What do they mean P0420 Catalyst below threshold?
Generally there are two Oxygen sensors – a pre-catalytic converter & a after catalytic converter. They do a few jobs (Look at KAMAHL holding the cat` you will see one small hole and a extension where the oxygen sensors fit)
- They monitor how much oxygen is in the exhaust emissions and they measure is the catalytic converter reaction buy monitoring the change of state (threshold). If the post cat sensor mirrors the pre-cat sensor, then the catalytic converter is not doing its job the fault code P0420 is registered. This information is monitored & compared through the computer in a term called closed loop.
What Causes the Failure?
There are number of reasons that can cause failure of a Catalytic converters. Vibration is probably the biggest killer. Exhaust systems have engine pulses which travel thousands a time a second these pressure waves can eventually break away the inner supporting structure-excessive over-fuelling through poorly tuned engines, coolant is one of the biggest killers- when a vehicle excessively over heats causing coolant to get in the exhaust system. Age, I am seeing vehicles around the 10 year mark coming in with this problem/fault code.
It’s so expensive to fix should I worry about it?
Well Yeah! When engine and emission lights come on, your vehicle is immediately un-roadworthy & if these hooligan climate activists have their way about climate change (running around half naked chaining themselves to toilet blocks & moving TRUCK WHEELS) will eventually force Governments to crack down on vehicle emissions.
This could mean you, the car owner & me the automotive repairer will face some serious fines if the repairs are not carried out immediately.
What this does do?
It puts serious stress on. Say single mothers to get their cars fixed straight away, whether they can afford it or not-..I would love to check the car emission status on all these screaming activists & see how well kept their cars are- people in green house glass houses should not throw stones!
I hoped this has helped- Manny
Knowledge is power- Power is organized effort!
Call Manny on 0411 496 621 today.
To Serve To Perform To Guide- Bringing Automotive power to the people
We have the latest diagnostic equipment and my work van is fitted out with an industrial air compressor. This enables me to perform heavy duty work and give you – the customer – the best service at any place and at any time.