I'm not endorsing either product, simply using them as examples of how/why a delete might impact the engine cooling. Below are two links to products designed to eliminate the EGR cooler and the EGR valve. The cooler relies upon engine coolant to cool the hot EGR gases. I did some research, and the concern around EGR on the 6.7L Cummins engine is that the exhaust gases on this system are cooled by an engine cooler. You're already concerned about engine/coolant temperatures rising under load on grades, eliminating the EGR valve could create more of an issue here. The same logic should apply to a diesel engine. For that reason, I have always cautioned against removing an EGR system or valve from a gasoline engine. In a gasoline engine without EGR, temperatures can soar above 4800 degrees F, enough heat to melt many metals. So, the intent of EGR is to lower combustion temperatures and cool the upper cylinders. Above 2500 degrees F, the engine's combustion process produces nitrogen oxide (NOx). That is enough reason to leave these systems alone, but I have some practical concerns as well.ĮGR (exhaust gas re-circulation) is a system designed to lower the upper cylinder temperatures in an internal combustion engine. Both measures would be illegal by EPA standards and cause a truck to fail the emissions test in states like California or Nevada with visual inspection and tailpipe readings. W ranch.I've watched the EGR and DEF removal trend with curiosity.