Q: How should reassemble Cylinder Head on 2005 Mercury Grand Marquis?
A: Regardless of whether the head was sent to an automotive repair shop for valve servicing, ensure it is clean before beginning reassembly. If the head was sent out for valve servicing, the valves and related components will already be in place, so start the reassembly procedure accordingly. On all engines, lubricate and install the valves, then install new seals on each valve guide, gently tapping each seal into place until seated. For models with specific seal types, use a hammer and a seal installer or deep socket to drive the seal onto the valve guide or head casting boss, ensuring not to twist or cock the seals during installation. On 4.6L engines, reinstall the valve lifters, lubricate and install the first valve, applying molybase grease or clean engine oil to the valve stem. Drop the spring seat or shim(s) over the valve guide and set the valve spring, retainer, and sleeve in place, noting that on 4.6L engines, the valve seal has the spring seat/shim incorporated into one piece. A valve spring should never sit directly against an aluminum cylinder head. Apply a small dab of grease to each keeper to hold it in place before installation, compress the springs with a valve spring compressor, and carefully install the keepers in the upper groove, ensuring they seat properly as the compressor is released. Repeat the procedure for the remaining valves, ensuring components are returned to their original locations. Check the installed valve spring height with a ruler or dial caliper, measuring from the top of each spring seat or shim to the bottom of the retainer, and if necessary, add shims under the springs to correct any height greater than specified, taking care not to shim the springs to a height less than specified. Finally, apply moly-base grease to the rocker arm faces and fulcrums, then install the rocker arms and fulcrums on the cylinder head studs.