To check the timing chain on all engines except the 4.9L, remove the timing cover and turn the
Crankshaft counterclockwise to take up slack on the left side of the chain. At the mid-point of the right side chain run, push the chain out with a finger while holding a graduated scale against it to establish an initial measurement using the centerline of one link pin as a reference. Then, push the chain in the opposite direction and measure the total deflection from the initial point. Compare this measurement to the specified figure; if excessive, replace the chain and both sprockets, as it is advisable to do so during a major overhaul. For the endplay check on all engines, use a magnetic base dial indicator. Push the
Camshaft to the rear of its travel in the block, install the dial indicator on the camshaft gear/sprocket retaining bolt, and zero it. Use a large screwdriver to pull the camshaft forward and release it, noting the reading on the dial indicator for the endplay measurement. If excessive, check the spacer installation; if correct and endplay remains too great, replace the thrust plate. For the 4.9L engine, check the timing gear backlash by installing a dial indicator on the cylinder block against the timing gear, zeroing the pointer, and moving the camshaft timing gear until all slack is taken up, then reading the dial indicator. If backlash is excessive, replace both the timing gear and the crankshaft gear. To check the timing gear runout, install a dial indicator on the engine block with the stem touching the timing gear face, hold the camshaft gear against the thrust plate, zero the indicator, and rotate the crankshaft to turn the camshaft while holding the gear against the plate. Observe the reading during one complete revolution; if runout exceeds specifications, check for foreign objects or burrs between the camshaft and gear flanges, and if none are found, replace the gears. A similar procedure applies to check the crankshaft gear runout, ensuring the crankshaft is against one end of the thrust bearing to avoid measuring endplay instead of actual runout.