Page 170 - 05. Subyek Teknik Mesin - Automobile Mechanical and Electrical Systems Automotive Technology Vehicle Maintenance and Repair (Vehicle Maintenance Repr Nv2) by Tom Denton

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154 Automobile mechanical and electrical systems

Modern engines use water cooling because this is capable of giving the precise
engine temperature control needed for exhaust emission regulations. Warming up
Key fact to the optimum temperature as quickly as possible is important, because it helps
Modern engines use water cooling not only to reduce exhaust emissions, but also to prevent the formation of water
because this is capable of giving particles in the combustion chamber and exhaust when the engine is cold. Any
the precise engine temperature water that does not evaporate can enter the engine and contaminate the engine
control needed for exhaust emission oil, or remain in the exhaust system and cause premature corrosive damage.
regulations.
The water jacket is cast into the cylinder block and cylinder head ( Fig. 2.142 ).
Casting sand is used to shape the inside, or core, of the casting for the water
passages. The sand is removed after casting through a series of holes in the
sides, ends and mating faces of the cylinder block and head.
The holes in the sides and ends of the block and head are machined to provide
accurate location for core plugs. The holes in the mating faces are aligned
to allow coolant fl ow from the cylinder block to the cylinder head. These
components are also machined for the fi tting of the water pump and a water
outlet to the radiator.
The internal designs of the head and block vary to give different coolant fl ow
patterns ( Fig. 2.143 ). An even fl ow to all areas of the engine is very important.

Figure 2.142 Engine block water jacket and core plugs

Figure 2.143 Coolant fl ow and temperature variations across the block