Coolant Flow in the Engine Block

Coolant flow in the Engine Block
The coolant flows from the water pump through the feed pipe (1) in the engine's V and to the rear of the engine block. This area has a cast aluminum cover (see the illustration). From the rear of the engine, the coolant flows to the external cylinder walls and from there into the cylinder heads.

The coolant then flows from the cylinder heads into the engine block V and through the return connection (3) to the thermostat housing. When the coolant is cold it flows from the thermostat (closed) directly into the water pump and back to the engine (recirculating for faster warm up).







When the engine reaches operating temperature (85 °C - 110 °C), the thermostat opens the entire cooling circuit to include the radiator.







The coolant flows to the rear of the engine block, from there through the side channels to the cylinder walls and then into the cylinder heads (lower left picture). The cast aluminum cover at the rear of the engine block (with sealing bead) is shown on the lower right.