F 350 4WD Super Duty V8-6.4L DSL Turbo (2008)
Thermostat: All Technical Service Bulletins
Cooling System - Coolant Leak At The Radiator
TSB 11-1-7
01/25/11
6.4L DIESEL ENGINES - RADIATOR LEAK DUE TO
HYPER-EXTENDED BYPASS THERMOSTAT
FORD:
2008-2010 F-250, F-350, F-450, F-550
This article supersedes TSB 10-17-9 to update the Service Procedure.
ISSUE
Some 2008-2010 F-Super Duty vehicles equipped with a 6.4L diesel engine may experience an external coolant leak at the radiator. This may be caused
by a hyper-extended thermostat. If the bypass thermostat hyper-extends, it causes the primary thermostat to oscillate. This oscillation causes thermal
spikes throughout the cooling system and stress on the radiator tubes.
ACTION
Follow the Service Procedure steps to correct the condition.
SERVICE PROCEDURE
1. Remove the radiator and thermostat. Refer to Workshop Manual (WSM), Section 303-03.
2. Inspect the bypass thermostat for being hyper-extended.
NOTE
THERMOSTAT RUBBER SEAL DAMAGE IS NOT RELATED TO RADIATOR FAILURE. A MISSING OR DAMAGED RUBBER SEAL
MAY IMPACT COLD WEATHER CAB WARM-UP ONLY AND SHOULD BE REPAIRED BY REPLACING THE THERMOSTAT.
a. Greater than 45 mm (1.77") - Hyper-extended. (Figure 1)
