Ford 8T4Z-6A257-A Camshaft Position Sensor

Turn the engine clockwise until the VCT units (camshaft sprockets) on each intake camshaft are positioned at 90-degrees (12 o'clock) in relation to the top surface of the cylinder heads. Remove the bolts that secure the valve train oil tubes to each cylinder head (Remove three of the camshaft cap bolts to remove the valve train oil tubes). Install the special camshaft locking tools (303-1248), with the tools holding the flats on each camshaft. If you can't see the timing marks on the timing chain, add a paint dot to align with the marks on the VCT units and the crankshaft timing sprocket. Remove the two bolts and the primary timing chain tensioner arm, then unbolt and remove the two tensioners. Remove the mounting bolts and remove the lower left chain guide, then the lower right chain guide. Remove the bolts securing the VCT solenoids to the cylinder heads (Remove the VCT oil control solenoid mounting bolts). You may have to twist or wiggle the solenoids to disengage them. Keep the VCT solenoids in clean plastic sandwich bags, marked with their location. Remove the primary timing chain. The two camshafts on each cylinder head are jointly driven by a smaller secondary timing chain. Depress and lock the secondary chain tensioner on each bank, using the factory tool (303-1530) inserted in the large hole at the first camshaft bearing cap, or use a length of threaded rod and nuts to hold the tensioner down, by pushing from the camshaft bearing cap. With the camshafts still locked at TDC, remove the mounting bolts from the VCT units (camshaft sprockets), then remove the sprockets and secondary timing chains from the camshafts. If the primary timing chain sprocket (at the center of the front of the block) is to be replaced, remove the nine bolts securing the plate that mounts the gear to the front of the block.

Lift the timing chain up and off of the VCT units, then off of the crankshaft sprocket. Slide the crankshaft inner sprocket off of the crankshaft.

Lift the rear timing chain from the cam sprockets and remove the chain.

Consult an expert. Double-check all your work and be sure everything is correct before you attempt to start the engine.