Mercury 8R3Z-6049-B Cylinder Head Assembly

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Remove the cylinder head bolts following the reverse of the recommended tightening sequence, loosening them in 1/4-turn increments. These are torque-to-yield bolts and should be discarded.

1. Relieve the fuel system pressure. 2. Disconnect the cable from the negative battery terminal. 3. Drain the cooling system. 4. Remove the strut tower cross brace mounting nuts and brace, if equipped. 5. Remove the valve covers. 6. Remove the intake manifold and the coolant crossover housing on 4.6L engines. 7. Remove the engine. 8. Remove the exhaust manifolds. 9. Remove the timing chain, tensioners, and sprockets. 10. Remove the camshafts. 11. Following the reverse of the tightening sequence, use a breaker bar to remove the cylinder head bolts. Loosen the bolts in sequence, 1/4-turn at a time. 12. Lift the cylinder head(s) off the engine. If resistance is felt, place a wood block against the end and strike the wood block with a hammer. Caution: The cylinder heads are aluminum; store them on wood blocks to prevent damage to the gasket sealing surfaces. 13. If the head sticks, use a prybar at the corners of the cylinder head-to-engine block mating surface to break the cylinder head gasket seal. Do not pry between the cylinder head and engine block in the gasket sealing area. 14. Remove the cylinder head gasket(s). Before removing, note which gasket goes on which side (they are different and cannot be interchanged).

Disconnect the alternator wiring and unbolt the alternator bracket. The bracket can be left in place with the upper bolt loose enough to swing it out of the way.

On all engines, lubricate and install the valves, then install new seals on each of the valve guides. Using a hammer and deep socket, gently tap each seal into place until it's seated on the guide. On V6 models, use a hammer and a seal installer to drive the seal onto the valve guide/head casting boss, ensuring the valve spring seat is in place first. Don't twist or cock the seals during installation or they will not seat properly on the valve stems.

Check the rocker arm pivot contact areas and fulcrums for cracks and wear.

Carefully position the cylinder heads on the engine block without disturbing the gaskets.

Most machine shops will not have a core set of heads unless the vehicle has been on the market for close to five years, meaning you may have to wait for the rebuilding work to be completed on your heads.

Check the installed valve spring height with a ruler graduated in 1/32-inch increments or a dial caliper. If the head was sent out for service work, the installed height should be correct, but don't automatically assume that it is. The measurement is taken from the top of each spring seat or shim(s) to the bottom of the retainer.

Ensure the new gaskets are installed on the correct cylinder banks, as they are not interchangeable.

Measure the margin width on each valve, ensuring it meets specifications; any valve with a margin narrower than 1/32-inch must be replaced.

Parts should be labeled or stored separately, such as in a small plastic bag with an appropriate label, to keep the valve train components together for reinstallation in their original positions.

Loosen the cylinder head bolts in 1/4-turn increments until they can be removed by hand, working in a reverse pattern of the tightening sequence.

The mating surfaces must be perfectly clean when the cylinder heads are installed.

Remove the upper intake manifold and the lower intake manifold.

Use a tap of the correct size to chase the threads in the cylinder head bolt holes, as dirt, corrosion, sealant, and damaged threads can affect torque readings.