Failure mode - Ford 6.4L Power Stroke

EGR cooler failure -> #8 hydrolock

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

Symptoms

white smoke, coolant loss, then the classic: no-crank hydrolock after shutdown (cooler drips into #8 overnight)
EGR cooler DTCs; coolant smell at the exhaust
worst case: bent rod from a restart attempt on a locked cylinder

Root cause

The 6.4 EGR cooler cracks and leaks coolant into the intake path; gravity feeds the nearest cylinder (#8) after shutdown - the sourced history names shutdown hydrolock on #8 as the mode. This is the 6.4's version of the 6.0's cooler problem, with a nastier ending if ignored.

Diagnosis

block-test the coolant; inspect the EGR cooler/intake for coolant traces
ANY no-crank-after-shutdown on a 6.4: suspect hydrolock BEFORE cranking - pull a plug/injector and check for fluid
track coolant loss history; do not keep topping up

Fixes

replace the EGR cooler immediately when leaking; inspect #8 for fluid before restart ()

egr-cooler (part category - specific model not chosen)

Prevalence

common