How to Find the EGR Valve in an Engine
What is an EGR valve
The EGR valve is an integral part of the emissions control system in automobiles. EGR stands for "Exhaust Gas Re-Circulation". Without it an automobile won't pass smog. It reduces the production of NOx (One vehicle produced by Chrysler doesn't require it).
When an engines internal temperature reaches 2500 F degrees the combustion process starts to produce NOx (nitrogen oxide). NOx is then expelled into the atmosphere via the exhaust pipe. Once in the atmosphere it is what is referred to as "air pollution". We breath the air, right? So NOx in the atmosphere is not good. That's where the EGR valve comes into play. It is designed to reduce the amount of NOx emissions from automobiles.
This is accomplished by recirculating a portion of the exhaust. Engines have a small passage between the intake and exhaust manifold. The EGR regulates this passage. When the valve opens, the engine draws in the exhaust through the EGR valve and puts it through the combustion process again. This causes the combustion temperature to decrease enough so NOx will be kept to a minimum.
If you hear "pinging" upon acceleration or erratic idling in your engine you should check the EGR valve for clogging or replacement. All that recirculated exhaust builds up carbon in the valve which can make it stick in the open or closed position.
Where is the EGR Valve?
If you've decided to clean the EGR valve or replace it all together, you'll need to locate it in the engine compartment. It is located on the intake manifold. What and where is the intake manifold you ask? I had a feeling some people may not know exactly where this is, so let's take this from the top down, just as if you had opened the hood and you're looking at the engine:
- The air filter is the highest setting item on the engine (nearly touching the hood when it's closed). Below the air filter is the...
- Carburetor. The carburetor is connected to the...
- Throttle body. Which is attached to the...
- Intake manifold where the....
- EGR is located.
The reason it's attached to the intake manifold, is so it can intercept the exhaust and recirculate it.
Mechanical & Electronic EGR
If you decided you'd like to try cleaning the EGR valve first, great! I always make an attempt at cleaning a part to see if that will fix it before I go and blow any cash on a new one. The more use you can get out of a part, the better. Waste not, want not, right.
There are two kinds of EGR valves; the mechanical type and the electronic type. First I'll go over cleaning the mechanical type:
- Locate the EGR valve in your engine.
Remove the vacuum hoses from the valve and inspect the lines. Spray carburetor cleaner inside the lines. Clean out the lines using a pipe cleaner if needed.
If there are bolts attaching the valve to the engine, remove them.
If the mounting gasket is in good shape you can set it aside and reuse it.
- Inspect and clean with carburetor cleaner and a toothbrush all the ports on the valve making sure the vacuum diaphragm moves freely.
- Replace any mounting bolts. Reattach hoses. And there you have it!
Now for the electronic type:
- Disconnect the negative battery cable from the battery. This will help avoid short circuiting the valve.
- Disconnect any sensors at the valve and remove any mounting bolts.
- Inspect the mounting gasket to see if it needs replacing. Set aside, if it is in good shape, to use when re-installing. If it is torn or compromised with oil or debris, replace it.
- Spray the valve and connecting hoses with carburetor cleaner and using a pipe cleaner and or toothbrush, clean out the lines. Make sure you avoid spraying the electrical connections or sensors. Carburetor cleaner will damage them. If the sensors and electrical connectors are in need of cleaning a special cleaner just for electrical connections is available at a reasonable cost.
- Place the gasket and reattach mounting bolts.
- Reconnect the hose lines and sensors.
- Hook up the negative battery cable. And you're done!
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