Ever stricter emission standards are also improving the techniques for reducing harmful CO2 emissions from diesel vehicles. Since the introduction of the EURO 4 emissions standard, manufacturers have been installing the so-called EGR systems with EGR coolers in their vehicles. As a result, exhaust gas emissions are noticeably reduced, particularly in the case of high-performance diesel engines. Extreme temperature fluctuations that occur during the combustion processes in the engine can also lead to defects in the EGR cooler. In the following article, you will find out which symptoms indicate an EGR cooler failure, what an EGR cooler is and what it does and also how to fix and clean an EGR cooler.
What Is An EGR Cooler And What Does It Do?
Installed between the exhaust and intake manifolds, the EGR cooler of the exhaust gas recirculation system (EGR) plays an important role in the combustion process. It is usually made of aluminum or stainless steel and it resembles a bottle-like device with multiple pipes and fittings through which coolant and exhaust gasses flow into the radiator. After leaving the cooler, the temperature-controlled exhaust gasses are fed back into the combustion system in precisely dosed quantities. This process already reduces the number of harmful nitrogen oxides before they reach the catalytic converter. The EGR valve is controlled by a control module and a converter that works mechanically, electro-pneumatically (EPW), or purely electrically (EDW).
Signs And Symptoms Of EGR Cooler Failure
An EGR cooler is not a part that commonly fails on a diesel engine, however, if a defect occurs, it is usually due to the extreme temperature fluctuations that occur in the cooler itself. Aggressive combustion products from in the cooler, which in the long term lead to a leak, often on the exhaust side of the cooler due to the high temperatures. Sometimes an EGR cooler can also “tear”. As a result, the exhaust gas pressure escapes in an uncontrolled manner, resulting in a lack of boost pressure from the turbocharger. Here are the most common signs and symptoms of EGR cooler failure.
White steam or smoke from the exhaust
The most common sign of an EGR cooler failure is white steam or smoke that comes from the exhaust. The white steam is caused by coolant leaking into the exhaust system and coming into contact with hot exhaust gasses. The coolant turns to steam when it comes into contact with the hot gasses, and this steam is visible as white smoke coming from the exhaust. If you notice white steam or smoke in the exhaust, you must take your car in for inspection as soon as possible. If your exhaust gas recirculation cooler fails, it may be time to replace it.
Lowered coolant level with no leaks
One of the signs and symptoms of an EGR cooler failure is a lowered coolant level with no leaks. Several things can cause it, but the most common cause is a leak in the EGR cooler. It can cause coolant to leak into the exhaust system, leading to a loss of coolant and an increase in engine temperature. If the cooler is not working correctly, the engine will overheat. If this occurs, it’s essential to address the issue immediately to prevent further damage and potential engine failure.
External coolant leakage
External coolant leakage is one of the signs and symptoms of an EGR cooler failure. When the exhaust gas recirculation cooler fails, it can cause the coolant to leak out of the cooling system and onto the ground. This can signify that the EGR cooler is not functioning correctly and must be replaced. External coolant leakage can also indicate other engine problems, such as an air leak or a broken turbocharger. If you are experiencing external coolant leakage and have any other signs of engine problems, please get in touch with your mechanic for further inspection. External coolant leakage can also be a warning sign that the cooler may need to be replaced soon.
Check engine light
The “check engine” light is a warning sign and one of the EGR cooler reasons for failure. When this light comes on, the vehicle’s computer has detected a problem with the engine’s exhaust gas recirculation (EGR) system. If the EGR system fails, dirty air and debris can build up in the engine’s cylinders, which can cause it to overheat and start smoking. So, if you see your “check engine” light come on, it’s vital to take action right away and have your car checked out by a mechanic.
If the engine is overheating, it is most likely that the EGR cooler is not functioning correctly. If the cooler is not working correctly, the exhaust gases will be hotter than they should be, and this can cause the engine to overheat.
Gooey EGR Valve
Gooey EGR Valve is among the signs of EGR cooler failure. The EGR valve recirculates exhaust gasses back into the engine. Over time, the EGR valve can become clogged with soot and carbon deposits, which can cause the valve to stick open. This can lead to several problems, including decreased engine performance, increased fuel consumption, and increased emissions. In some cases, a stuck EGR valve can also cause the engine to catch on fire.
Reduced fuel efficiency
When the EGR cooler fails, it can cause reduced fuel efficiency. EGR cooler failure can cause the engine to run richer, which will lead to reduced fuel efficiency. Additionally, the cooler may not be able to cool the exhaust gas properly, leading to reduced fuel efficiency. Finally, the cooler may become clogged, reducing fuel efficiency. This symptom indicates that the cooler is probably failing and should be replaced.
Reduced engine power
Reduced engine power may be one of the signs and symptoms of an EGR cooler failure. When the cooler fails, it can cause the engine to lose power and may cause the engine to run rough. EGR cooler failure can also cause the engine to overheat and damage, resulting in reduced engine power. In extreme cases, this can lead to total engine failure.
Poor emissions readings
The main symptom of an EGR cooler failure is poor emissions readings. The EGR cooler is responsible for recycling exhaust gasses back into the engine. If it is not functioning correctly, the engine will not be able to properly combust these gasses. This will result in higher than regular emissions readings.
Difficulty starting the vehicle
One of the symptoms of an EGR cooler failure is difficulty starting the vehicle. The vehicle may take longer to start than usual or not start at all. In some cases, the car may start but then stall shortly after. If the cooler fails, it may not be able to properly cool the exhaust gasses, which can lead to problems with the engine, thus difficulty starting the vehicle.
Burning smells coming from the engine
If you notice burning smells coming from your engine, it could be a sign that your EGR cooler is failing. The exhaust gasses can overheat and cause a burning smell if the cooler is not working correctly. If the cooler is not working correctly, the exhaust gases can escape and cause an unpleasant odor. In addition, the EGR cooler helps keep the engine cool; if it fails, the engine may overheat and eventually start to smoke. If you experience this sign and symptom, take your car for inspection.
Decrease in acceleration
If the EGR cooler is failing, it will cause a decrease in acceleration. If the cooler is not working correctly, the exhaust gasses will not be adequately cooled and will not be able to be recirculated. This will cause a decrease in acceleration. The increased exhaust gas temperature can also cause the catalytic converter to malfunction.
Why Does An EGR Cooler Fail?
An EGR cooler mainly fails due to the following three reasons:
- Thermal exposure
Extreme temperatures and temperature fluctuations (from 200°C and upto 900°C) represent a big stress factor for the stainless steel or metal body of the EGR cooler. After many cycles of these extreme conditions, the housing of the EGR cooler begins to warp and crack.
- Rust and environmental factors
Not all EGR coolers are made out of rust-free metals that easily withstand the impacts of the environment. Rust and corrosion are detrimental when it comes to cracking of the housing of the EGR cooler.
- Blocks and clogging
The unsatisfactory flow of the coolant is the most common consequence of a blocked EGR cooler. The restricted coolant flow will lead to overheating of the EGR cooler, consequently also EGR cooler damage and increased NOx emissions.
How To Fix It?
In 90% of the cases, getting a replacement EGR cooler is the only solution to this problem. However, in countries where emissions testing is not as strict, many people decide to just delete the entire EGR system. Aftermarket auto part manufacturers are selling so-called “EGR delete kits” which eliminate the use of the EGR system. The car will run just fine without the EGR system, however, there is a bigger impact on the environment and your car might not pass the emissions testing.
Cleaning an EGR cooler
If the only thing wrong with the EGR cooler is clogging or a blockage, a professional cleaning procedure might be the way to go. The most effective cleaning procedure involves ultrasonic cleaning technology that is offered by specialized repair shops. It usually costs around 130$, including the labor. However, many DIY mechanics also tackle the problems on their own by removing the EGR cooler and leaving it soaking in water and detergent until all the deposits inside the cooler dissolve. After a good rinse, the EGR cooler is good to go. We do recommend visiting a specialized workshop if you have never done this before.
If you do want to clean your EGR cooler at home, please see this guide.
We already mentioned that in 90% of the cases, a replacement EGR cooler is the only solution. The cost of a new EGR cooler greatly varies between car brands and different engines. The average cost of a new EGR cooler will cost you anywhere between 200$ and 3000$.
Frequently Asked Questions
How often should you replace the EGR cooler?
There is no fixed lifespan of an EGR cooler. In theory, it should outlast the car, it is not a part that is commonly replaced. However, car manufacturers predict it should last at least 80,000 miles.
How long does it take to replace an EGR cooler?
According to our online research and a consultation with a Volvo service technician, it should take no more than 2-3 hours.
Can an EGR cooler be cleaned?
Yes, an EGR cooler can be cleaned. In order to clean it, it must be removed from the engine. Cleaning the EGR cooler is not possible without removing it from the engine.