Guide to the EGR Cooler

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The exhaust gas recirculation (EGR) system is part of the emission control system on most modern diesel engines. Its purpose is to reduce nitrous oxide emissions and improve fuel economy.

However, this system has a lot of issues, one of which is that the recirculation process can lead to overheating. For that reason, many big diesel engines use EGR coolers to reduce the temperature of the hot exhaust gas before it recirculates through the system.

The EGR system is found everywhere in the auto industry and is used in many types of diesel engines, including marine engines. Heavy-duty diesel engines have been using the EGR system since the 1970s, but it didn’t reach the mainstream until the early 2000s.

Components of the EGR System

EGR Valve

Controls the flow of exhaust gases into the intake manifold.

Types of EGR Valves:

Vacuum-controlled (older systems).
Electronic (newer systems, controlled by the ECU).

EGR Cooler

Cools the exhaust gases before they are reintroduced into the intake, lowering combustion temperatures and reducing NOx formation.

EGR Bypass Valve

Allows the system to bypass the EGR cooler under specific conditions to prevent condensation or freezing of exhaust gases.

EGR Temperature Sensor

Monitors the temperature of exhaust gases entering the EGR system to ensure proper functioning.

EGR Pressure Feedback Sensor (DPFE)

Measures the pressure differential in the EGR system to determine how much exhaust gas is flowing.

EGR Vacuum Solenoid

Regulates the vacuum applied to the EGR valve (in vacuum-operated systems).

Intake Manifold

Receives recirculated exhaust gases along with fresh air and fuel for combustion.

Piping and Hoses

Carry exhaust gases between the exhaust manifold, EGR cooler, and EGR valve.

Exhaust Manifold

Collects exhaust gases from the engine cylinders and directs them to the EGR system.

Optional Components:

EGR Filter: Found in some systems to trap particulates before gases are recirculated.
NOx Sensor: Monitors NOx levels to ensure emissions compliance.
EGR Actuator: In electronically controlled systems, it assists in operating the EGR valve.

ProSource Diesel examines the function of the EGR cooler, whether it needs to be cleaned, and when it should be replaced.

What is an EGR Cooler and What Does It Do?

The EGR cooler works with the EGR valve to reduce emissions by creating a mix of air, fuel, and exhaust gas. It injects a coolant into these gases to lower their temperature.

The EGR system works to lower combustion temperatures by using a small amount of inert exhaust gas to dilute the air/fuel mixture. This reduces the chance of chemical reactions that create pollutants.

However, this mixture-dilution action is even more effective if the exhaust gas is at a lower temperature. That’s where the EGR cooler comes in. The EGR cooler consists of a series of tubes or one hollow tube through which exhaust gas passes.

Several coolant passages surround the tube system, allowing heat to pass through the walls and deliver cooler gases.

What Happens When the EGR Cooler Goes Bad?

The heat from the exhaust system goes to the engine’s cooling system and any additional heat is dissipated through the radiator. However, failures inside the EGR cooler can cause failures elsewhere in your cooling system.

This may lead to overheating, coolant loss, and engine damage. How do you spot failure before it gets bad? The first clue is usually white exhaust smoke. This telltale sign is actually steam from your coolant boiling.

However, white smoke can also indicate other problems, like a failed head gasket. Another thing to keep an eye on is your coolant overflow container. If it keeps going down and you don’t see any leaks on the ground, then coolant might be exiting through the exhaust due to a leaking EGR cooler.

Another sign is if you notice that your EGR valve looks like it’s been steam cleaned. Normally, the EGR valve ends up black from carbon buildup. However, when coolant enters the EGR system, it can mix with the carbon and turn it into a sticky buildup.

That usually means there are only small amounts of coolant in the system. Large amounts will have the steam-cleaning effect.

Why Does the EGR Cooler Fail?

Too much stress is the main reason for EGR cooler failure. Overuse can cause the coolant valve walls to break down, ruining the connection between the cooler and the exhaust. This causes gas to pass back into the engine at a hotter-than-normal temperature.

Sometimes, the turbo is part of the problem. A computer regulates how much boost the engine needs. If the boost is lowered, the cooler is less stressed. On the other hand, if the boost is increased, the flow of the EGR valve is also increased, which puts more stress on the cooler.

Some EGR coolers just aren’t built with enough durability to last. Many stock coolers are thin and oval-shaped, which increases the chance of failure due to excess heat and pressure. The best way to prevent failure is to clean and maintain your EGR cooler regularly.

How To Clean an EGR Cooler

For cleaning, you’ll find the EGR cooler between the turbo and the EGR valve. Soot and debris can reduce airflow or clog your EGR cooler. The inside of the cooler might also be dirty, especially if your cooling system is oil-based.

To clean your EGR cooler, soak the part in a detergent to dissolve the debris. You can then remove and clean the filter. Let everything dry before reinstalling.

It’s best to use a cleaner specifically made for the EGR cooler, but you can also use all-purpose cleaners. It’s important not to use anything flammable, as it might ignite inside the engine.

Ensure all debris and any remaining cleaner have been removed before reinstalling the part.

Replacing Your EGR Cooler

How to replace the EGR cooler core on 2011-2016 Ford 6.7L Diesel

If your stock EGR cooler fails, you’re not the only one. Many diesel truck owners find themselves in this position after using their trucks to tow or haul a lot. Unfortunately, heavy use can put enough stress on a stock EGR cooler to cause it to fail sooner than expected.

Fortunately, it’s not that difficult to get a replacement EGR cooler when you shop at ProSource Diesel. Enter your truck’s make and model or the engine you’re searching for to get the right part. Installing a replacement EGR cooler may differ depending on the engine, and it can be a time-consuming process.

Ultimately, the EGR cooler is an important part of your modern diesel engine system, and you can’t operate without it. If you suspect signs of failure, it’s important to find a replacement part immediately. ProSource Diesel has you covered with an expansive inventory of diesel truck parts for popular diesel engines, including Cummins, Duramax, and Powerstroke.

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