1.2 Cylinder Head
DETROIT DIESEL 53
warpage, under ordinary conditions, reduces valve reconditioning to a minimum.
To ensure efficient cooling, each fuel injector is inserted into a thin-walled tube which passes through the water space in
the cylinder head. The lower end of the injector tube is pressed into the cylinder head and flared over; the upper end is
flanged and sealed with a neoprene seal. The flared lower end and sealed upper end prevent water leaks around the
copper tube.
The exhaust passages from the exhaust valves of each cylinder lead through a single port to the exhaust manifold. The
exhaust passages, exhaust valve inserts and injector tubes are completely surrounded by cooling system water.
In addition to being surrounded by water, cooling of these areas is further assured by the use of double jet spray nozzles
installed between each pair of cylinders in the water inlet ports of four valve cylinder heads. Nozzle holes are so
positioned in the cylinder head that the comparatively cool water which enters the head is directed at high velocity
against the sections of the head which are subjected to the greatest heat.
To seal compression between the cylinder head and the cylinder liner, separate laminated metal gaskets are provided at
each cylinder. Water and oil passages between the block and head are sealed with synthetic rubber seal rings which fit
into counterbored holes in the block. A synthetic rubber seal fits into a milled groove in the block near the outer edge of
the area covered by the cylinder head. When the cylinder head is pulled down, a positive leakproof metal-to-metal
contact is assured between the head and block.
Certain service operations on the engine require the removal of the cylinder head. These operations are:
1. Removing and installing the pistons.
2. Removing and installing the cylinder liners.
3.
Removing and installing the exhaust valves.
4.
Removing and installing the valve guides.
5.
Reconditioning the exhaust valves and valve seats.
6.
Replacing the injector tubes.
7.
Installing new cylinder head gaskets.
8. Removing and installing a camshaft.
Cylinder Head Maintenance
Engine temperatures should be maintained between 160 and 185F. and the cooling system should be inspected daily
and kept full at all times.
Unsuitable water in the cooling system may result in lime and scale formation which prevent proper cooling. The cylinder
head should be inspected around the exhaust valve water jackets. This can be done by removing an injector tube. Where
inspection discloses such deposits, a reliable non-corrosive scale remover should be used to remove the deposits from
the cooling system of the engine, since a similar condition will exist in the cylinder block and other components of the
engine. Refer to Section 13.3 for engine coolant recommendations.
Adding cold water to a hot engine may result in head cracks. Water must be added slowly to a hot engine to avoid rapid
cooling which will result in distortion and cracking of the cylinder head (and cylinder block).
Loose or improperly seated injector tubes may result in compression leaks into the cooling system and cause a loss of
engine coolant. The tubes should be tight and properly seated. Refer to Section 2.1.4.
The development of cracks in the cylinder head may be caused by abnormal operating conditions or through neglect of
certain maintenance items. If this type of failure should occur, a careful inspection should be made to determine the
cause so that a recurrence of the failure will be prevented.
Overtightening the injector clamp bolts may also result in head cracks. Always use a torque wrench to tighten the bolts to
the specified torque.
Other conditions which may eventually result in head cracks are:
1. Excess fuel in the cylinders due to leaking injectors.
2. Oil pull-over due to an overfilled air cleaner sump, or improper viscosity oil in the air cleaner.
3. Neglected cylinder block air box drains which allow accumulated oil to be drawn into the cylinders.
Remove Cylinder Head
Due to various optional and accessory equipment used on the different engine models, only the general steps for
removal of the cylinder head are covered. If the engine is equipped with special accessories that affect cylinder head
removal, note the position of each before disconnecting or removing them to assure the correct reinstallation.
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