The manufacturer recommends adjusting the valve clearance at the specified interval only if the valve train is making excessive noise. Begin by disconnecting the cable from the negative terminal of the battery. Next, remove the valve cover. For manual transmission vehicles, set the parking brake and place the transmission in neutral; for automatic models, place it in Park. Remove the spark plugs and position the number 1 piston at TDC on the compression stroke, aligning the timing marks. Measure the clearance of the indicated valves with a feeler gauge when the piston is at TDC on the compression stroke, ensuring to feel a slight drag on the gauge if the clearance is correct. Record each measurement and compare with the desired valve clearance specifications, noting any that are out of specification for later reference regarding required replacement lifters. Turn the crankshaft 240 degrees clockwise and measure the clearances of the indicated valves, then turn it an additional 240 degrees clockwise and measure again. The V6 engine does not use valve adjusting shims; if a lifter is out of specification for clearance, it must be replaced with a new lifter of a different thickness. Mark the lifters to be replaced and record their corresponding valves, using a micrometer to measure the thickness of each lifter precisely at the center. To calculate the correct thickness for a replacement lifter that will achieve the desired valve clearance, use the provided formulas for both intake and exhaust sides. New lifters are available in 27 standard thicknesses, ranging from 0.3102 inch to 0.3291 inch, and are marked on the underside for size identification. Mark the new lifters for their installation locations, lubricate them with engine assembly lube, and install them. After replacing the lifters, reinstall the camshafts, and complete the installation in reverse order of removal.
