Some 2001-05 Ford Taurus and Mercury Sables, 2001-06 Ford Escapes and 2005-06 Mercury Mariners (all with the 3.0-liter four-valve V6) may produce a ticking sound from the engine bay. According to Ford, the noise usually comes from the left bank of the engine, typically occurs at normal operating temperature and is due to excess clearance between the intake cam and its bore. Removing, then reinstalling the camshaft caps should eliminate the condition.
Start the job by removing the lefthand valve cover. Next, rotate the engine clockwise until the No. 6 cylinder cam lobes are all pointing upward. This ensures that the valves are closed. Remove all the intake cam caps. Don't just loosen and retighten the cap bolts, warns Ford, because it probably won't be enough to properly reindex the cam in the bore!
Now reinstall the intake cam caps and torque the retaining bolts to 72 in-lbs. in the following sequence: No. 1 cap, No. 2 cap, No. 3 cap, No. 5 cap. Using a screwdriver or pry bar on each side of the No. 4 cap, shift the cap toward the exhaust side of the cylinder head. Once it's there, torque its cap bolts to 72 in-lbs also. To complete the fix, install the valve cover, check the oil level, then start the engine to verify that the ticking noise has been eliminated.