Failure mode - Ford 3.5L EcoBoost Gasoline (F-150, Expedition, Transit, Raptor - 2011-present)

Cooling service: thermostats, hoses, degas system under tow load

Reliability tier: aggregated - verify before ordering, see /disclosure/

Symptoms

coolant smell / puddles (thermostat housing, hoses)
temps creeping on long pulls
degas bottle level swings

Compare with the other causes of the same sign on this engine: losing coolant (2 causes) · overheating or temperature creeping up (2 causes)

Root cause

Conventional cooling wear (thermostat housings, hoses, degas system) on a turbo engine that runs hot under tow; separate from the internal-water-pump FM, which carries the catastrophic-risk story.

Diagnosis

pressure-test and trace external leaks (housing, hoses, degas)
verify thermostat opening temps against spec under load
rule out the water-pump FM (internal weep, coolant-in-oil check) before condemning external hardware

Cooling service: thermostats, hoses, degas system under tow load

Symptoms

Root cause

Diagnosis

Fixes

Prevalence

Affected configurations (62)