Exhaust Gas Recirculation(EGR) valves do exactly what they say, Recirculate Gas.
Exhaust Gas Recirculation (EGR) valves do not normally require maintenance, but can become clogged with carbon deposits.
Carbon Deposits can cause the Exhaust Gas Recirculation (EGR) valve to stick or prevent it from opening or closing properly.
An Exhaust Gas Recirculation (EGR) Valve that’s stuck open, will act like a vacuum leak and cause a rough idle and stalling.
An Exhaust Gas Recirculation (EGR) Valve that has failed, refuses to open will allow elevated emissions and may also cause detonation (spark knock).
Different Valve Types That Do The Same Job:
Exhaust Gas Recirculation
- Ported EGR valves (1973 to 1980s).
- Positive backpressure EGR valves (1973 & up).
- Negative backpressure EGR valves (1973 & up).
- Pulse-width modulated electronic EGR valves (early 1980s & up).
- Digital electronic EGR valves (late 1980s to 1990s).
- Linear electronic EGR valves (early 1990s & up).
Exhaust Gas Recirculation (EGR) Valve-Failure Symptoms:
Most (EGR) valve failures happen because the valve itself gets stuck open or closed. This is due to build-up of soot particulates, carbon deposits and a sticky tar-like substance. So, A faulty EGR valve should cause an ‘engine check’ light to turn on. This is to inform the driver that something that affects the engine’s emissions is not working correctly. However, before getting to total failure, the (EGR) valve will slowly degrade in operation.
As a result, causing it to react slower to input and partially stick. If the valve is stuck fully closed, it would cause higher temperatures within the cylinder, theoretically leading to knocking. However, as most modern engines have knock sensors, they’ll most likely adapt and it probably won’t feel all that different. Most likely it will stick open when it should not, causing a rough idle leading to a reduction in performance.
This degradation over time will be slow but should be noticeable. It will also mean worse fuel economy. Carbon deposits accumulate rapidly, especially if most of your driving happens within the city and short trips. This driving pattern doesn’t allow the engine to reach operating temperature and run long enough to remove harmful carbon deposits.
Exhaust Gas Recirculation (EGR) Valve-Cleaning:
Depending on the EGR valve, it may be possible to extend its life by cleaning it rather than replacing it. However, to do the job thoroughly you’ll need to remove the valve to clean it. Consequently, This could end up taking more time than replacing it with a new valve. But, if successful will obviously be a cheaper fix.
Exhaust Gas Recirculation (EGR) Valve-Replacing:
Most DIY mechanics should be up to the task of replacing an (EGR) valve. We’d recommend taking pictures of the engine bay and connections to and from the EGR valve. Let the engine cool down, disconnect the battery and wait a few minutes for the electrical system to discharge completely. Isolate the battery terminals as well to prevent shorting. Before removing anything, check that the replacement (EGR) valve you’ve bought looks identical to the old one.
If the (EGR) valve has vacuum pipes to it, label them before twisting and pulling the pipes off. Then carefully take off any electrical connections. This should be possible by hand, even if they are tight. The valve itself may be mounted within a sturdy outer body, bolted to the cylinder head. Because it has hot exhaust gases going through it at times the bolts holding it on may be particularly tight.
It’s always a good idea to spray these bolts with a lubricant such as WD40. This will help remove stuck bolts. Once the bolts are all off, take the valve and body out. Remove any remnants of any old gaskets.
Simply reverse the process above with the new valve to fit it to the engine.
If You Want To Take The Chance Of Just Cleaning It
Cleaning the EGR valve assembly is a two-step deal.
- It really depends on how far you want to go and how much time you have. First, soak the EGR valve in a bowl filled with carb cleaner. Carb cleaner smells horrible and is nasty stuff. so soak it outside or in a very well-ventilated area. Important: If your EGR valve has electronic connections on it, do not submerge the electrical portion in cleaner! Let it soak overnight if you can. If this isn’t possible, skip to the next step.
- Once you’ve let your EGR valve soak in cleaner overnight (if possible) you need to clean its passages, openings. and surfaces with a small brush. Toothbrushes and pipe cleaners are great. The more black crud you get out of there the better your chances of fixing the problem. Important: When hand cleaning, be sure to use chemical resistant gloves and EYE PROTECTION. Carb cleaner is nasty stuff. Basically, you want to clean everything you can reach with your cleaning brushes.