What is EGR Cooler? | Symptoms and causes of a bad EGR Cooler

Exhaust Gas Recirculation (EGR) is the most important part of the vehicle engine. It reduces the combustion temperature by diluting an air-fuel mixture with a small amount of inert exhaust gases. The EGR cooler is a major part of the EGR system. It is employed to lower the temperature of the exhaust gas before it is recirculated to the engine intake. This article mainly explains the function, symptoms and causes of a bad EGR cooler.

What is an EGR Cooler?

The EGR (exhaust gas recirculation) cooler is used to reduce emissions of nitrogen oxides (NOx) from vehicle exhaust. It is also used to reduce the exhaust gases’ temperature before they are recirculated into the engine intake.

The recirculation of the NOx emissions can significantly reduce engine heat and pressure. In general, it significantly reduces emissions. The latest car engines require the use of a recirculation system to fulfill the current US Environmental Protection Agency emissions standards.

EGR Cooler

The EGR cooler is located in between the EGR valve and the turbocharger. It contains various hollow tubes to allow hot exhaust gases to pass through it. There are multiple coolant channels around these tubes.

The heat transfers to the cooler, inert exhaust gases through the wall separating the exhaust gases from the coolant, allowing for a lower maximum combustion temperature. The vehicle CPU system uses to control the flow of exhaust gas through the EGR cooler.

The engine cooling system absorbs the full heat of the exhaust system. This extra heat is only removed via the radiator—the EGR cooler links to the engine’s cooling and exhaust systems. Therefore, failures within the cooler can generate many issues such as coolant leaks, engine overheating, blown head gasket, and engine damage.

Symptoms of a bad EGR Cooler

When the EGR cooler goes bad, it produces one of the below given symptoms:

  1. White smoke from the tailpipe
  2. Low coolant level with no leaks
  3. External coolant leakage
  4. Check engine light
  5. Gooey EGR valve
  6. Engine overheating

1) White smoke from Tailpipe

White smoke from the exhaust pipe is one of the common symptoms of a bad EGR cooler. When the cooler leaks, the coolant starts leaking into the EGR system due to that vehicle is emitting white smoke.

As the EGR cooler fails, it discharges a large amount of coolant into the exhaust system. As the coolant enters the exhaust system, the exhaust gases interact with the coolant and turn into white vapors. These vapors exit the vehicle exhaust pipe as white smoke.

2) Low Coolant Level without Leaks

As previously mentioned, a sufficient amount of coolant is very important for the proper cooling of the engine. Too little coolant can cause cavitation and insufficient cooling. If your coolant is reducing very quickly, but there are no visible leaks, it means that your EGR cooler is damaged internally.

Read More: Signs and Causes of Coolant leaks

3) Check Engine Light

Normally, the vehicle’s ECU has the ability to detect engine-related issues. If your vehicle cooler has a problem or not working properly, the ECU turns on the check engine light. In either case, you should check the engine as the check engine light turns on. This light is installed on the dashboard of the vehicle.

Read More: Causes and Symptoms of a bad ECU

4) External Coolant Leaks

The external leakage of the coolant may also cause due to a damaged or bad EGR cooler. This external leakage is easy to identify and fix.

5) Gooey EGR Valve

One of the best suitable methods to inspect an EGR cooler for damage is to pull the EGR valve. This valve is most commonly installed near the engine oil filter on top of the engine. When you remove the valve, it should be full of dry black charcoal carbon from the exhaust system.

If the EGR cooler is broken, there will be a black gooey mess on the valve. This black gooey mess produces due to the interaction of the hot coolant with the hot exhaust gas and the vapor cleaning of the EGR valve.

Read More: Function and working of EGR Valve

6) Engine Overheating

The engine overheats due to insufficient working of the engine. Engine overheating is one of the most common symptoms of a bad EGR cooler.

Over time, carbon can build up inside the cooler, which may limit the coolant flow through the cooler. If the EGR cooler fails, the exhaust gases can’t cool efficiently, and the engine may overheat. The engine overheating may cause of different parts failure.

Causes of a bad EGR Cooler

There are multiple causes of EGR cooler failure, but the most major causes are given below:

  1. Corrosion: According to the application nature, some EGR coolers may damage due to corrosion. This corrosion may occur due to wear or deposits from the condensation of particles or acids at low temperatures.
  2. Clogging: In some cases, the coolant passages of the cooler can be clogged, which stops the efficient cooling of the exhaust gases. You need to disassemble the system to identify the clogged passages, but higher fuel consumption or engine overheating can also indicate this problem.
  3. Thermal Stress: Exhaust gas recirculation can cause the EGR cooler to crack or warp. The cooler is exposed to exhaust gases that can reach 800°C and is then cooled to about 200°C. Over time, the cooler can become damaged, which can lead to leaks or full failure of the system.

How to clean the EGR Cooler?

Follow the below-given steps to clean your EGR cooler:

  1. Remove the cooler from the vehicle.
  2. Fill the cooler with a detergent.
  3. Let the cooler soak in the detergent to dissolve deposits.
  4. Thoroughly rinse the cooler to remove the loose deposits.
  5. Let the cooler dry, then reinstall it.

Many repair shops use an ultrasonic cleaner to clean EGR coolers, particularly filthy passageways. When running detergent thru the passageways, these ultrasonic waves shake the carbon loss. This may significantly expedite the cleaning procedure.

How to diagnose a failed EGR Cooler?

There are a few things you can check to determine whether or not your EGR cooler has failed:

  • Check your coolant level. If your engine is consuming more coolant than the expected amount, it means that your EGR cooler may be cracked and leaking coolant into the exhaust system.
  • Is there white smoke coming from the engine’s exhaust pipe? If the EGR cooler is cracked, the coolant will leak into the exhaust system and vaporize.
  • Remove the EGR valve. Does the EGR valve look wet, gummed up, or steam cleaned? This may be due to a damaged cooler. 
  • Check the engine for overheating. The engine overheating may also cause due to a faulty cooler.

FAQ Section

What is the EGR Cooler replacement cost?

The replacement cost of a bad EGR cooler varies according to your living area, type of car, and type of brand. The EGR cooler replacement cost is from $270 to $3800. Higher-end pricing usually applies to modified or high-performance engines, so you are likely looking at the lower end of the spectrum for a passenger car.

What are the causes of a bad EGR cooler?

There are multiple causes of a bad EGR cooler, but the following are the major causes:

  1. Corrosion
  2. Clogging of cooler passages
  3. Thermal Stress

What happens if my EGR cooler fails?

EGR cooler failure can compromise the integrity of your vehicle, leading to severe engine damage, coolant leak, exhaust leak, white Smoke, engine overheating, and possible impairment of other components. It can also go unnoticed for some time, as the symptoms are not always obvious.

Can EGR cooler be cleaned?

EGR coolers are similar to radiators, although they utilize water to cool heated exhaust gases rather than air to cool the heated water. This means they can be maintained in the same way as a radiator.

Can you drive with a bad EGR valve?

Technically, you can drive your vehicle with a bad EGR valve, but your vehicle will run rough, shake at idle, and a check engine light will be illuminated. You might also hear popping sounds while driving down the road.

EGR cooler failure can compromise the integrity of your vehicle, leading to severe engine damage and possible impairment to other components.

How often should you replace the EGR cooler?

The EGR cooler is an integral part of your vehicle that ensures your engine runs efficiently and that you’re doing your part and not releasing as much noxious exhaust. Typically, you can expect to get about 80,000 miles out of the part, but defects and damage may cause its lifespan to be shortened.

Where is the EGR cooler located?

The EGR cooler is located on top of the passenger side valve cover. Besides the EGR pipes, only the air filter lid and intake tube need to be removed.

What damage can a faulty EGR valve cause?

A faulty EGR valve can cause problems with the flow and operation of the EGR system leading to performance issues including a power reduction, reduced acceleration, and decreased fuel efficiency. It can also cause vehicle emissions to increase.

How often should you replace the EGR cooler?

An average car’s EGR valve has a lifespan of approximately 10 years in service.

Can a bad EGR valve cause overheat?

If coolant flow is restricted, the EGR cooler is unable to cool the exhaust gases. This not only allows NOx emissions to continue but also causes overheating, which can cause serious damage.

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