BOLT 6V8927 - Caterpillar

Coolant Circuit
Illustration 1 g01029677
Cooling system schematic (typical example) (1) Turbocharger drain lines (2) Water cooled turbocharger housing (3) Aftercooler (4) Vent lines (5) Deaerator (6) Expansion tank (7) Raw water heat exchanger (8) Riser to water cooled manifold (9) Water pump inlet (10) Water cooled manifold (11) Tube from expansion tank to water pump (12) Jacket water pump (13) Manifold (14) Jacket water heater (15) Bonnet (16) Oil coolerThe 3408 and 3412 High Performance Marine Engines use a separate raw water pump, an integral surge tank, and a heat exchanger in order to provide a more compact engine installation. The jacket water cooling system is a pressure type cooling system. The system is designed with the following components that are water cooled:
exhaust manifolds
risers
turbochargersThis pressure type cooling system can operate safely at a temperature that is higher than the normal boiling point (steam) of water. A pressure type cooling system also helps to prevent cavitation which can damage engine components. Cavitation is the sudden formation of low pressure bubbles that are caused by mechanical forces in liquids. An integral deaerator is built into the jacket water cooling system in order to remove air bubbles from the coolant. The formation of air or steam pockets is more difficult within a pressure type cooling system. The extensive use of water cooled manifolds helps to minimize excess heat that would be radiated into the engine room.
Illustration 2 g01029686
(6) Expansion tank (7) Raw water heat exchanger (12) Jacket water pump (17) Raw water inlet (18) Raw water pump (19) Turbocharger supply from blockThe jacket water pump (12) forces coolant into manifold (13). The coolant flow is then divided. Part of the coolant from the water pump is sent to the aftercooler (3) in order to cool the inlet air for the engine. From the aftercooler core, the coolant then enters the cylinder block at the top rear of the engine. This flow is directed from the rear of the cylinder block into the rear of the cylinder heads toward the front of the engine. The coolant exits the cylinder heads at the front of the engine