Download FORD: 2008-2010 F-Super Duty This article supersedes TSB 10-4-5 to update the a. With EOT at 195 °F (91 °C) drive on the Dealer Coding base part numbers. highway unloaded at 55-70 MPH (89-113 Km/h) constant speed to observe EOT and ISSUE ECT temp. Some 2008-2010 F-Super Duty vehicles built on or b. Test results/next steps: before 9/14/2009 and equipped with a 6.4L diesel engine may exhibit repeat radiator leaks due to (1) If EOT is less than 8 °F (4.4 °C) malfunctioning (hyper-extended) high temperature higher than ECT, and the coolant temp thermostats. fluctuates roughly 5 °F (2.7 °C) – the thermostats are okay and do not need ACTION to be replaced. Replace just the Follow the Service Procedure steps to correct the radiator. Refer to WSM, Section 303-03 condition. (Engine Cooling). SERVICE PROCEDURE (2) If EOT exceeds ECT by greater than 8 °F (4.4 °C) or if the ECT readings 1. Verify the coolant leak is from the radiator, refer fluctuate 10 to 12 °F (5.55-6.66 °C) to pinpoint test (PPT) A found in the Workshop roughly every 30 seconds – replace Manual (WSM), Section 303-03. both thermostats and radiator. Refer to 2. Verify the venturi tee is installed. WSM, Section 303-03 (Engine Cooling). a. If installed, confirm it is installed correctly (note – orientation direction on part). 5. If vehicle is not drivable and the coolant leak is found to be from the radiator, remove and b. If not installed, install Venturi Tee Kit on replace both thermostats and radiator.