loader image
Posted in: Blog

What is an EGR Cooler and Why Do We Need Them?

EGR (exhaust gas recirculation) became part of the emissions control system in heavy-duty trucks as early as 2002. This part recycles exhaust gas through the EGR cooler and back into the engine’s cylinders to burn with the new fuel. The aim of the EGR is to cut your emissions by burning exhaust more thoroughly and boosting your fuel efficiency. As a by-product, the EGR cooler protects your engine by lowering your combustion temperature with cooled exhaust gas.

So, what does an EGR cooler do exactly?

After combustion, the cylinder’s exhaust valve opens and the waste gas flows through the exhaust manifold into the EGR cooler. In the cooler, the antifreeze coolant lowers the temperature of the exhaust before it cycles back into the engine. By controlling the combustion temperature, this cooled gas helps your engine work efficiently and stops it from running too hot. The EGR also boosts fuel economy by returning the cooled gas to the combustion chamber to prevent your engine from burning over-rich fuel!

How Important are EGR Coolers?

By recirculating your exhaust gas, the EGR helps cut your NOx emissions. This is vital because NOx gases are highly toxic, contributing to smog and acid rain! They also contribute to poor air quality in populated areas, which is especially bad for people with respiratory issues like asthma. The cooler is a vital part of the EGR: it dilutes the air-fuel mixture in the cylinder with cooled exhaust gas, lowering the combustion temperature. This stops the engine from overheating and the lower temperatures improve the performance of hot components like the cylinder head. 

What Happens When the EGR Cooler is Blocked?

The average EGR cooler lasts about 80,000 miles or 128,7475km, though existing faults or damage from upstream issues can shorter its life. The tubes and EGR valve can also become clogged with carbon build-up over time. If this happens, your rig will likely throw a DTC code like insufficient EGR cooling. If it’s a simple blockage, it may be quicker and cheaper to have your EGR cleaned rather than replaced.

Over time, it’s also possible for the coolant lines in your EGR cooler to become clogged. This is more common in older EGRs or in coolers running on low-quality or contaminated coolant. If your coolant lines are blocked, you’ll usually notice a drop in EGR performance, an increase in fuel consumption and issues with your engine overheating. If the lines are blocked but not damaged, you can usually clean them without needing to replace them. This can take anywhere from 3 to 8 hours depending on your dealer and how much work is required. On the flip side, EGR coolers can also develop the opposite problem and become leaky.

How Do You Tell if the EGR Cooler is Leaking?

EGR coolers are exposed to exhaust gases as hot as 800°C, which are then cooled to about 200°C. Over time, constant exposure to extreme temperatures can cause old EGR coolers to crack or warp, leading to coolant leaks. The EGR cooler can also become corroded from continual wear or from particle condensation at low temperatures. These are the most common signs of a leaky EGR cooler:

White Smoke: White exhaust smoke could be a sign that your coolant lines are leaking, and the coolant is mixing with hot exhaust gas. The hot exhaust can also burn the coolant, leading to low coolant levels.

Low Coolant Levels: This could also happen if a leak or crack in the outer case of the EGR cooler is allowing coolant to seep out.

Sticky/ Gooey EGR Valve: If coolant escapes into the EGR valve, it can mix with the carbon residue there. This makes the valve sticky and stops it from opening and closing properly.

Check Engine Light: If the check engine light comes on and you scan for DTC codes, it’ll alert you to any EGR issues. A fault code like ‘insufficient flow’ could indicate a clog or leak in the cooler!

Truck image to illustrate blog on EGR cooler failure

What Happens When an EGR Cooler Fails?

You can drive for a short time with a bad EGR cooler, but it won’t be good for your engine, and you’ll notice signs like rough idling. If you ignore a bad EGR cooler for long enough, it can cause cumulative damage. This includes exhaust issues, engine overheating, an increase in toxic emissions, and even problems with the turbo. Often, smaller issues with the EGR cooler like clogged tubes can be fixed without needing to replace the whole part. However, if you can’t fix the problem, you should replace the EGR cooler, so you don’t risk damaging the engine or other aftertreatment parts.

Does EGR Shorten the Engine Life?

Engineers have resolved many of the kinks that were common in early EGR models. In current designs, the cooler temperatures they provide can actually prolong the life of many components in your engine. As long as it’s functioning properly, your EGR should benefit both your engine and aftertreatment system. If you run into issues, it’s best to have your EGR repaired or replaced because running your truck with a blocked EGR can damage your engine. It’ll also increase the likelihood of DTCs, as the truck’s temperature and exhaust sensors will flag up the non-functioning EGR as an issue. If you illegally delete your EGR to avoid repairing it, you’ll risk hefty fines, void your engine’s warranty and make technicians unwilling to work on your truck.

Replacing or repairing your EGR cooler quickly if you notice a fault is the best way to protect your engine and turbo from damage and prevent coolant leaking into your exhaust manifold. To save time and money on factory repairs or replacements, it’s also worth looking into aftermarket EGR coolers!

Does Roadwarrior offer aftermarket EGR Coolers?

Roadwarrior has just introduced replacement EGR coolers as the latest addition to our aftermarket catalogue. To start with we’re only offering replacement Cummins and Detroit Diesel coolers, but we’re planning to expand our offering to other OEMs going forwards. These parts are designed to be reliable, direct-fit replacements that meet OEM standards without the OEM price tag. Our replacement EGR coolers are built to protect your engine from damage, prevent coolant leaks into the exhaust manifold and boost your fuel economy!

Better Coating, Better Performance.

Roadwarrior is the only manufacturer to use Metalcor® catalyst technology across its entire range of Diesel Oxidation Catalysts (DOCs) and Selective Catalytic Reduction catalysts (SCRs). Metalcor® catalysts feature high activity catalyst coatings fused to thinner, stronger, catalyst substrates to guarantee maximum performance under the harshest conditions.

Metalcor® catalyst coatings are designed and produced in our own labs. We then inspect each unit to ensure you get more fuel efficiency, lower consumption of DEF, and long term performance from your heavy duty engine!


Roadwarrior Has You Covered!

All Roadwarrior emissions parts carry a full value 12 month warranty.

LightningVolt lithium batteries carry a full value 30 month warranty.

To make the process hassle-free, our parts have a metal nameplate with the serial number, so even after 500,000 miles of service, it’s still easy to identify. This avoids the common problem of serial numbers printed on stickers that burn off after the first start-up, making them impossible to return. Our failsafe system allows us to work in your interests, honouring claims for on-road and off-road replacements, and giving you peace of mind.

And since Roadwarrior parts are designed to meet or exceed OEM specifications, you can rest easy knowing our direct fit parts will take the problems out of your aftertreatment without interfering with your OEM warranty.

Next Day Is Nice, Same Day is Better!​

A faulty emissions control system can cost you thousands in wasted man-hours as your heavy equipment sits in the shop awaiting a new part. Whether it’s a truck behind on orders, a bus that can’t take passengers, or heavy machinery delaying construction deadlines, Roadwarrior can get you moving again! 

Roadwarrior has twelve warehouses across the U.S.A. and Canada, which can deliver the most popular aftertreatment parts in 1-2 days. With over 1,000 DPFs, DOCs and SCRs on offer, Roadwarrior offers the largest aftertreatment catalogue.

*LightningVolt lithium batteries ship directly from Roadwarrior in Ontario, to ALL 50 states, including Alaska and Hawaii within 2-4 days.