Honda 12300-RDJ-810 Cylinder Head Assembly, Rear (Dot)

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To remove the components, first relieve the fuel pressure, disconnect the electrical connectors from the fuel injectors, disconnect the fuel lines, and remove the fuel rails. Next, disconnect the cable from the negative battery terminal, drain the cooling system including both block drains, and remove the alternator. Then, take out the ignition coils from the valve covers, remove the power steering pump without disconnecting the hoses, and detach the upper and lower intake manifolds along with the exhaust manifolds. After that, remove the timing belt covers, detach the timing belt, and take off the camshaft sprockets. Label and remove all electrical connectors at the lower intake manifold, then remove the coolant passage assembly from the cylinder head by taking out the mounting bolts and lightly tapping the passage to break the gasket seal. Remove the rocker arms/shafts assembly, loosen the cylinder head bolts in 1/4-turn increments until they can be removed by hand, and lift the cylinder head off the engine block, prying carefully if it is stuck. For installation, ensure the mating surfaces of the cylinder heads and block are clean, using a gasket scraper and cleaning with lacquer thinner or acetone. Check for any damage on the mating surfaces, chase the threads in the head bolt holes, and clean them with compressed air. Clean the oil-control jets and reinstall them with new O-rings, then position the new gaskets. Carefully set the head on the block, measure the thread diameter of each head bolt, and replace any that do not meet specifications. Apply clean engine oil to the threads and under the bolt heads before installing and tightening them in the recommended sequence. The remaining installation steps follow the reverse order of removal, after which reconnect the battery, refill the cooling system, change the oil and filter, run the engine to check for leaks, and allow it to operate at low speed for five minutes to bleed air from the lost motion assemblies, noting that some tappet noise may occur initially.

After removing the valve cover and rocker arms/shafts assembly, you should proceed to remove the fuel rails and injectors, followed by the lower intake manifold(s).

The new head bolts should be installed following the recommended sequence, especially on certain Acura and Honda models where the torque is applied twice. It is important to tighten them properly.

12205-PJ7-305 / GUIDE, EX. VALVE (OVER SIZE) 6 94302-06100 / PIN B, DOWEL (6X10) 2 12204-PJ7-305 / GUIDE, VALVE (OVER SIZE) 6 90701-P8A-A00 / PIN, DOWEL (6X10) 2 12207-634-300 / WASHER, SEALING BOLT 1 12208-P8C-A01 / BOLT, SEALING (28MM) 1 12207-PC6-300 / WASHER, SEALING (16MM) 1 90083-PG1-000 / BOLT, SEALING (16MM) 1