The Ford Motorcraft F7TZ-6A636-AAA (F7TZ6A636AAA) is a genuine OEM rear oil cooler mounting gasket engineered specifically for 1994–2003 Ford F-250, F-350, F-450, and F-550 Super Duty and OBS trucks, 2000–2003 Ford Excursions, and 1994.5–2003 Ford E-Series vans equipped with the 7.3L Powerstroke diesel engine. Positioned between the driver-side rear of the engine block and the rear oil cooler/filter header casting, this precision-die-cut gasket creates a leak-free seal across high-pressure engine oil feed channels and engine coolant passages. Manufactured from heavy-duty, oil- and coolant-resistant composite gasket material directly to original Ford specifications, it maintains dimensional stability and clamping tension under intense thermal cycling and high hydraulic pressures.

External oil weeping down the driver-side oil pan rail, coolant seepage around the oil filter mount, loss of engine oil pressure caused by blown gasket material, and oil-into-coolant contamination at the rear block interface are what this genuine replacement gasket cures. Because the rear oil cooler header routes oil directly to the oil filter at full base engine oil pressure (40–70 PSI) alongside circulating cooling system passages, degraded or flattened aftermarket gaskets frequently rupture or weep over time. Installing the genuine Ford F7TZ-6A636-AAA gasket ensures precise port alignment, proper crush resistance, and a reliable seal that prevents fluid cross-contamination. It is a single OEM rear oil cooler-to-block mounting gasket; the front header gasket (F4TZ-6A636-A), internal silicone O-rings, and oil cooler bundle are sold separately.

It fits all 1994–1997 Ford OBS and 1999–2003 Ford Super Duty F-250, F-350, F-450, and F-550 trucks, 2000–2003 Ford Excursions, and 1994.5–2003 Ford E-250, E-350, and E-450 Econoline vans equipped with the 7.3L Powerstroke turbo diesel engine.

Fitment

• 1994–1997 Ford F-250 / F-350 7.3L Powerstroke Turbo Diesel (OBS)
• 1999–2003 Ford F-250 / F-350 / F-450 / F-550 Super Duty 7.3L Powerstroke Turbo Diesel
• 2000–2003 Ford Excursion 7.3L Powerstroke Turbo Diesel
• 1994.5–2003 Ford E-250 / E-350 / E-450 Econoline Van 7.3L Powerstroke Turbo Diesel
• Genuine Ford OEM replacement gasket ensures exact port alignment and sealing
• Engineered to seal high-pressure engine oil passages and pressurized coolant ports simultaneously
• Constructed from high-temperature, oil- and coolant-resistant composite gasket material
• Direct replacement for original factory part number F7TZ-6A636-AA
• Driver-side rear engine block-to-oil filter header mounting location
• Eliminates oil and coolant leaks along the driver-side frame rail and oil filter base
• Individual rear oil cooler header mounting gasket (sold individually)

Position a large drain pan underneath the driver side of the engine, open the radiator drain valve, and completely drain the engine cooling system; spin off and discard the engine oil filter, draining residual engine oil. Unbolt the three rear oil cooler header mounting bolts securing the filter housing to the engine block, unbolt the front header mounting bolts, and lower the entire oil cooler assembly out from under the vehicle. Peel away the old rear gasket and thoroughly clean the engine block mounting pad and rear cast aluminum header surface using a plastic scraper and brake cleaner until the metal is completely clean, flat, and oil-free (do not use aggressive wire wheels on aluminum). Align the dry Ford F7TZ-6A636-AAA gasket onto the clean engine block mounting dowels or hold it in position against the rear header (do not use RTV silicone on this composite gasket, as sealant can squeeze into oil ports and cause bearing starvation). Position the oil cooler assembly against the engine block, start all mounting bolts by hand to ensure proper alignment, and torque the rear header-to-block bolts in an alternating sequence to 18 ft-lbs (24 Nm). Install a new oil filter, refill the crankcase with 15W-40 diesel oil, refill and bleed the cooling system with a 50/50 diesel coolant mix, and run the engine to verify zero oil or coolant leaks at the rear header interface.