The 2020 Infiniti QX60 equipped with the 3.5L V6 uses an EGR (Exhaust Gas Recirculation) cooler to reduce exhaust gas temperatures before reintroducing them to the intake. This cooler uses engine coolant and can develop leaks that cause coolant loss and other symptoms.
Understanding the EGR Cooler
The EGR system recirculates a portion of exhaust gas back into the intake to reduce combustion temperatures and NOx emissions. The EGR cooler uses engine coolant to cool the hot exhaust gases before they enter the intake manifold. This heat exchanger operates under harsh conditions with hot exhaust on one side and pressurized coolant on the other.
Failure Modes
EGR coolers can fail internally or externally. Internal failure allows coolant to enter the exhaust gas passages, where it may be ingested by the engine or exit through the exhaust. External failure causes visible coolant leaks from the cooler housing or its connections. Thermal stress and corrosion cause most EGR cooler failures.
Symptoms of EGR Cooler Leaks
External leaks show as coolant dripping from the cooler area, often toward the rear of the engine. Internal leaks cause white steam from the exhaust, coolant level dropping without visible external leak, possible rough running or misfires if coolant enters cylinders, and sometimes sweet smell from the exhaust. Check engine light with EGR codes may illuminate.
Diagnostic Process
Visual inspection may reveal external leaks or crusty residue around the EGR cooler. For internal leaks, pressure test the cooling system watching for pressure loss without visible leaks. Exhaust gas analysis may show coolant contamination. Borescope inspection of the EGR passages can reveal internal coolant accumulation.
Repair Considerations
EGR cooler replacement is the typical repair for significant leaks. The component is relatively expensive and labor can be significant depending on accessibility. Some owners explore EGR delete options where legal, though this affects emissions compliance. Always use OEM or quality replacement parts as cheap coolers may fail prematurely.