Mazda RX-2 and 616 Workshop PDF Manual

COOLING SYSTEM The completely sealed cooling system consists of a corrugated fin type radiator with sealed filler cap. expansion tank with pressure cap, centrifugal water pump, wax pellet type thermostat, and a four-blade fan. The radiator and the expansion tank are connected by
hose. When engine is overheated, the coolant in the radiator flows out and led into the expansion tank through the hose. The coolant is then returned to the radiator by negative pressure which builds up in the cooling system when the engine cools down. The coolant should be changed every two years or every 48.000 km (32.000 miles).

3-A. COOLANT CIRCUIT The water pump, which is driven by a belt from the crankshaft, delivers the coolant from the radiator through the inlet pipe to the water jackets on the cylinder block and the cylinder head. When the engine is cold, the themostat is closed and the coolant in the water jacket does not circulate back into the radiator but is delivered back to the inlet pipe after passing theough the hot spot on the inlet
manifold to preheat the air and fuel mixture. As the coolant circulates only between the water jackets and the inlet pipe, this enables the engine to warm up quickly.

Once the engine is warmed up, this opens the thermostat and the coolant is then circulated through the hot spot only to the inlet pipe but also to the radiator through the thermostat. The coolant in the radiator is cooled by the fan and the air stream caused by the travel of the vehicle and is then circulated to the water jackets

3-C. CLEANING OF COOLING SYSTEM
The cooling system should be flushed every 48.000 km (32,000 miles) or every two years. The flushing procedures are as follows:
1. Open the drain cocks and drain the coolant.
2. Close the drain cocks and supply clean soft water (demineralized water). Note: If necessary, use cleaning solution to loosen the rust and scale, according to the instructions given by the maker of the cleaning solution.
3. Run the engine for about one hour keeping the normal operating temperature.
4. Drain the coolant completely and flush clean water through the cooling system in the direction opposite to the normal coolant flow. This action causes the water to get behind the corrosive deposits and force them out.
5. Fill with a mixture of MAZDA genuine long life coolant and soft water (demineralized water).

3-D. RADIATOR
The radiator is of a coorrugated fin type with a sealed filler cap. The capacity of the radiator is 2.6 liters (0.7 U.S. gallons, 0.6 imp. gallons).
Examine the radiator carefully for leakage. If any leakage should be discovered, repair completely by soldering, etc. Clean the exterior of the radiator core by blowing out with compressed air.

3—D—1. Expansion Tank Pressure Cap
The pressure cap is provided on the expansion tank. The expansion tank and the radiator are connected by the hose. The pressure in the cooling system increases the boiling point of the coolant and prevents overheating and reduces overflow losses. When the pressure in the cooling system exceeds 0.9 kg/cm1 (12.8 lb/in2), the pressure valve opens. A vacuum release valve is employed to prevent un- desirable build-up when the system cools down

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