It is important that before fitting the replacement cylinder head, the cause of the original failure is identified, and where appropriate, remedial action is taken. Failure to do so may result in similar problems with the replacement cylinder head, which will not be covered by the cylinder head warranty. Before installation, always visually check that the replacement cylinder head is compatible with the unit it is replacing.
Always carefully read any information or instruction labels that may be supplied in the box, or fixed to the cylinder head or packaging, as they may be specific to the cylinder head supplied.
It is good practice that all ancillary parts should be thoroughly cleaned prior to refitting to the exchange unit.
In the case of overhead camshaft engines, timing chains / timing belts and their tensioners should always be replaced. Any gears, guides and idlers should be carefully inspected and replaced as necessary.
Thoroughly clean the cylinder block face using a suitable solvent based product. Remove all traces of the old gasket and any carbon deposits taking care not to damage the block face and not to contaminate any oil feed holes.
Check the flatness of the cylinder block face. If it is distorted by more than 0.05mm over the length of the block, it should be refaced.
All threaded holes for the cylinder head bolts should be thoroughly cleaned and blown clear with an airline to insure that there is no contamination with gasket material or fluids. Any particles or fluid remaining in the holes may affect the clamping load of the cylinder head bolts and in extreme cases can cause the cylinder block to fracture.
Insure that any locating dowels are undamaged and are fitted correctly.
Cylinder Head Gasket
The surface finish of the supplied cylinder head has been matched to the construction of the manufacturer’s original cylinder head gasket.
The performance and service life of the cylinder head is dependent on fitting an OE quality cylinder head gasket of the same construction as the original.
Diesel engines may use various thicknesses of head gasket to accommodate the piston protrusions. The thickness of the cylinder head gasket is usually identified by a number of holes or notches on the edge of the gasket. The new gasket should be same thickness as the one it is replacing. If in doubt, or if the engine has been subject to other repairs, the piston protrusions should be measured and a gasket of the correct thickness fitted.
Please note: The thickness of the cylinder head gasket required has no relation to the cylinder head, only the piston protrusions. Different gasket manufacturers may not use the same identification marks.
Most cylinder head gaskets are marked OBEN or TOP, and this side should be facing upwards once installed. Do not apply any type of sealant to the cylinder head gasket unless instructed by the gasket manufacturer. Camshaft carriers should only be fitted and sealed with the OE manufacturers recommended sealing product which should be used sparingly as any excess sealant can block oil ways.
Cylinder Head Bolts / Studs
It is imperative that any stretch bolts are replaced with new and the manufacturers correct tightening sequence and torque procedures are followed (including re-torqueing if required). Also follow the manufacturer’s recommendations for cylinder head bolt lubrication.
Before fitting the replacement cylinder head, we recommend that the radiator be checked by a specialist and replaced if necessary.
It is essential that the complete cooling system functions efficiently. The hoses and hose clips should be carefully checked for wear and leaks, and we would always recommend that a new water-pump and thermostat are fitted. All switches, sensors and cooling fans should be checked for operation. On initial running, ensure the coolant is circulating correctly and that the system is de-aerated. The cooling system should only be filled with an antifreeze mix or the original manufacturer’s recommended coolant.
If the previous failure resulted in contamination of the cooling system with oil, then we strongly recommend that the entire cooling system (including the heater matrix) be cleaned with a proprietary cooling system cleaning product and all hoses are replaced.
Exhaust & Intake Manifolds
These must be thoroughly cleaned and checked for cracks, corrosion and distortion. They must be fitted correctly; the securing nuts/ bolts/ studs must be tightened in the correct order and to the correct torque. Bolt and stud threads should be treated with a sealing compound to prevent oil/ coolant leakage.
Many intake manifolds are fitted with butterfly or other variable valves, and these should be checked for wear and serviceability before they are re-fitted.
If the original failure resulted in engine debris entering the induction system, then it is essential that all traces of debris are removed to prevent this being sucked back in to the engine, thus causing further damage.
Oil & Oil Filter
The engine oil and oil filter should be replaced when the cylinder head is installed.
Starting the Engine
ALWAYS check oil and coolant levels are correct before starting the engine. It is advisable to disable the fuel or ignition systems, and to turn the engine via the starter motor until the oil pressure indicator light goes out.
After running the engine, check the oil and temperature gauges. If there is low oil pressure or the engine temperature is too high, stop the engine immediately and check for possible causes.
The tappets, where manually adjustable, must be reset after the engine has been run up to operating temperature. Where the cylinder head requires retorquing the tappet clearances should only be reset after the head has been re-torqued.