passages in the cylinder block and cylinder head form the engine waterjacket (fig. 6-4).
In the cylinder block, the water jacket completely surrounds all cylinders along their
full length. Within the jacket, narrow passages are provided between the cylinders for
coolant circulation around them. In addition, water passages are provided around the valve
seats and other hot parts of the cylinder block In the cylinder head, the water jacket
covers the combustion chambers at the top of the cylinders and contains passages around
the valve seats when the valves are located in the head.
of the water jacket are designed to control circulation of coolant and provide proper
cooling throughout the engine. The pump forces coolant directly from the lower radiator
tank connection into the forward portion of the cylinder block. This type of circulation
would, obviously, cool the number one cylinder first; causing the rear cylinder to accept
coolant progressively heated by the cylinders ahead. To prevent this condition, the L-head
block is equipped with a coolant distribution tube that extends from front to rear of the
block, having holes adjacent to (and directed at) the hottest parts of each cylinder.
I-head engines are equipped with ferrule type coolant directors that direct a jet of
coolant toward the exhaust valve seats.