Exhaust Gas
Recirculation is a method used to reduce emission of Nitrogen Oxide in diesel
and petrol engines. This mechanism re-circulates portions of the exhaust gases back
to the cylinders of the engine. It works by the principle that, Nitrogen Oxide
forms due exposure of a mixture of both Nitrogen and Oxygen to high
temperatures. Therefore, EGR ensures lower temperatures in the combustion chambers
hence limiting the production of Nitrogen Oxide. Was that too brief to understand? Well, am
not yet done. EGR is a valve controlled
by vacuum and allows a certain quantity of exhaust to get back to the intake
manifold. When the exhaust mixes with the intake air, it cools the combustion
process. This avoids high temperatures hence discouraging formation of Nitrogen
Oxide.
Types of EGR valves
There are three major
types of EGR valves. Though they almost function similarly, each type has some
unique features from the others. These types include;
1.
Positive backpressure EGR valve: This
valve allows the exhaust to pass freely within the pintle shaft. The pressure
contained in the gasses directs the movement of the shaft allowing free circulation
of air in the engine. This type of valve has a “p” label on it.
2.
Negative backpressure EGR valve: This
type is controlled by both an engine vacuum and impulses. The engine vacuum
ensures backpressure while the impulses regulate the flow of gases inside the
engine.
3.
Single Diaphragm EGR valve: This valve
is controlled by an engine vacuum, an opening and a diaphragm; whereby the vacuum
ensures flow of pressure to the diaphragm. At certain levels of temperature,
the diaphragm triggers the valve to open. When the valve opens, it lets in some
exhaust gases which lower the temperatures in the combustion chamber.
How to determine the
right EGR valve for your car
Well, after knowing the
different types of EGR valves, you may get confused in deciding the best valve to
purchase for your car. The knowledge about the major types of EGR valves will
give you a better chance to decide the best type to purchase for your car.
Though they all work the same, some have different unique features from others.
These features may include; a pintle, a diaphragm and an opening. You should
also consider the quality and brand of the EGR valve before purchasing. The
prominent manufacturers can be trusted to provide high quality products. The
cost is also another important aspect to consider. In order to know the best
price offer without compromising the quality of the product, you may need to
compare the price stated by different prominent retailers.
Replacing
an EGR valve
After several miles of
driving, your EGR valve may develop problems hence creating a need for
replacement. It takes only a few minutes to replace the EGR valve following a
simple process.
Step 1: Determine the
location of the EGR valve by the help of your car owner’s manual since it may
differ in different models of cars.
Step 2: Disconnect the
battery, the intake hose, the vacuum hose and any wiring attached to the EGR
valve by use of a screwdriver.
Step 3: Carefully
unscrew all bolts holding the valve to the car’s engine and remove it from the
EGR tube using a socket wrench. The need for a replacement comes only when you
see holes in the valve. If there are no holes, just clean it using a carburetor
cleaner and gasket scraper.
Step 4: You may now put
back all the parts which you had removed and test whether everything is
working.
That is a very simple
process, and in addition, it will help you to save some dollars you would have
paid to a mechanic for the same service.
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