Timing Gear Cover Gasket Compatible With John Deere 4020/4230/4430/4440 1969-1988 6404/6466 6.6L

JOHN DEERE TRACTORS:
• John Deere 4020/4230/4430/4440/4630/4640 6404/6466 6.6-7.6L Diesel (1969-1988)

JOHN DEERE COMBINES:
• John Deere 6600/6620/7700/7720 6404/6466 Diesel (1970-1988)


IMPORTANT:
This timing gear cover gasket fits the John Deere 6404/6466 engine family — the older 6.6-7.6L inline 6-cylinder diesels used in 4020/4230/4430/4440/4630/4640 tractors and 6600/6620/7700/7720 combines from the 1969-1988 era. The 6404 and 6466 share the same basic block architecture but differ in bore size. This gasket fits both variants. Note that the timing cover on these engines also changed by serial number — verify your engine serial number to ensure compatibility.

Failure symptoms: oil seeping from the front timing cover, oil on the crankshaft pulley/damper area. When replacing, inspect the front crankshaft seal and replace if hardened — the labor fully overlaps. Also inspect the timing gear cover for cracks, particularly around bolt holes. Clean all old gasket material from both surfaces before installation. These engines are over 35 years old — if the timing cover is being removed, inspect the timing gears for wear or backlash while accessible.

⚠️ Verify 6404 or 6466 engine and serial number before ordering.