Symptoms

Overheating or temperature creeping up

What causes it depends on the engine. 29 documented failures on 18 engines list this among their signs. Pick your engine for the causes ranked, how to tell them apart and the usual fix.

6.0 Power Stroke (2003-2007) 6 known causes, most widespread: EGR cooler failure 6.4 Power Stroke (2008-2010) 2 known causes, most widespread: Front-cover pump cavitation erosion (coolant into oil) 6.7 Power Stroke (2011-present) 1 known cause: Dual-circuit cooling system leaks (radiator / crossover tube / degas bottle / water pump) 6.7 Cummins 2007-2018 3 known causes, most widespread: Water pump failure Ram 1500 EcoDiesel (2014-2019) 1 known cause: Oil cooler oil/coolant cross-contamination Duramax LB7-LMM (2001-2010) 1 known cause: EGR cooler clogging / failure (LB7-LMM) Duramax LML (2011-2016) 1 known cause: Cooling system wear: water pump, fan clutch, oil cooler (LML) Duramax L5P (2017-present) 2 known causes, most widespread: DPF ash loading / excessive regeneration + differential pressure sensor Duramax 3.0 (LM2/LZ0) 1 known cause: Coolant flow control valve failure (active thermal management) 3.2 Power Stroke (Transit) 2 known causes, most widespread: EGR cooler failure: overheating and coolant loss (three Ford field actions) 6.2 Boss (gas) 1 known cause: Cooling service (water pump / thermostat / degas) 7.3 Godzilla (gas) 1 known cause: Cooling service (water pump / thermostat / degas) 3.5 EcoBoost (gas) 2 known causes, most widespread: Internal water pump: coolant loss and coolant-into-oil risk Transit V6 (gas) 1 known cause: Cooling service: thermostat/housing and hoses 6.4 HEMI (gas) 1 known cause: Cooling service (water pump / thermostat) ProMaster 3.6 (gas) 1 known cause: Cooling: water pump, thermostat housing and coolant bottle leaks GM 6.0 L96 (gas) 1 known cause: Cooling system wear: water pump, fan clutch, thermostat (L96) GM 6.6 L8T (gas) 1 known cause: Cooling system wear: water pump, hoses, thermostat (towing duty)

Built from the failure-mode records on this site: a failure is listed when its own symptom list describes this sign. Engines not shown have no documented failure with it in our records. How we tier and source facts.