The EGR Cooler and the Domino Effect
The illustration to the right details how coolant moves through the 6.0L Power Stroke engine. Notice that after coolant leaves the oil cooler, it flows to the exhaust gas recirculation (EGR) cooler. The EGR cooler uses engine coolant to remove heat from a portion of the spent exhaust gases as they're directed back to the vehicle's intake to help reduce the creation of NOx (nitrogen oxide) emissions. The EGR system is a vital component of the emissions control system. Some companies sell EGR block-off devices that eliminate the functionality of the EGR system altogether, though these kits are for off-road use only and typically cause the "check engine" light to illuminate. The better solution is a Bulletproof EGR cooler with an improved core structure for better flow characteristics.

Inside the EGR Cooler:
Two Common Problems

If you have owned a Ford Super Duty pickup with the 6.0L engine, chances are you have experienced an EGR cooler failure. Ford released several technical service bulletins to its dealer network in an attempt to resolve these problems. However, none of them address the root cause of the problem, and though the dealership may replace faulty EGR coolers under warranty, the issues will continue to persist. Once you've seen the inside of one of these EGR coolers as we have, it's easy to understand their shortcomings.

1. This is an example of a failed EGR cooler that caused a catastrophic engine failure. Notice the cracked coolant passageway (arrow). This unit failed because of a clogged oil cooler and excessive exhaust gas temperatures. This type of failure is typically caused by running an aggressive tuner or chip on a 6.0L with coolant flow issues. You see, the EGR cooler is the next place engine coolant goes after leaving the factory engine oil cooler. When the coolant side of the oil cooler is restricted, the EGR cooler cannot cool hot exhaust gases effectively. The EGR cooler was never designed to handle extreme heat and therefore develops a rupture or crack. When this type of failure occurs, coolant will mix with exhaust gases inside the EGR cooler—not good.

2. This photo shows the other type of EGR failure that Bulletproof Diesel encounters regularly. Exhaust gases deposit gunk on the cooling fins inside the EGR cooler. This causes restriction within the unit. This restriction cuts down on the EGR's effectiveness, allowing higher exhaust gas temperatures to reach the intake manifold. Generally, this type of failure can be traced back to a clogged engine oil cooler. As the coolant side of the oil cooler becomes restricted, less heat is scavenged from the engine oil. This results in higher coolant temperatures and a lower volume of coolant exiting the oil cooler. As the restricted and hot coolant reaches the EGR cooler, the hot exhaust gases "flash-boil" the coolant in the adjacent channels of the EGR cooler. This failure usually results in loss of coolant from the coolant reservoir. This condition typically leads to a rupture failure of inside the EGR cooler, and eventually results in blown head gaskets.

3. The redesigned Bulletproof EGR cooler features a much more robust interior, with six round stainless-steel tubes in place of the factory three oval-shaped tubes. The benefits of this upgrade are staggering. Thanks to improved coolant flow, the EGR cooler can remove heat from exhaust gases effectively. Improved coolant flow cools exhaust gases better, which helps to prevent gunk deposits inside the cooler. The design also prevents the coolant from flash-boiling, thanks to decreased dwell time inside the unit. When coolant and exhaust gases pass through the EGR cooler as intended, heat can be removed from the exhaust gas before it is blended with the air charge. The result is cleaner combustion with fewer emissions.