Engine Cooling System Cadillac Brougham I

The engine cooling system consists of a radiator, radiator cap, water pump, thermostat, cooling fan, heater core, engine coolant passages and connecting hoses. A coolant recovery reservoir is used on most vehicles to maintain radiator level during expansion and contraction of coolant.

Engine cooling fans range from belt driven flex or clutch type, to electronically controlled electric cooling fans. Electric cooling fans operate only when conditions require fan operation. When trouble shooting electric cooling fans, refer to appropriate ELECTRIC COOLING FANS article in this section.

THERMOSTAT

Most thermostats are thermal wax pellet type. As coolant temperatures rise the wax begins to expand. This expansion overcomes spring tension allowing the thermostat to open. Some thermostats also incorporate an additional bleed hole to allow a small amount of circulation and helps eliminate air locks.

PRESSURE CAP

Modern cooling systems use a closed system type cap. This system allows for coolant expansion during engine operation. As coolant expands and builds pressure, some coolant is permitted to bleed past the cap into the overflow tank. When the engine cools and coolant contracts, the cap allows the coolant in the overflow tank to siphon back into the system.

The pressure cap also increases pressure in the cooling system. The increased pressure raises the boiling point, one pound of pressure raises the boiling point approximately 10° F (12.2° C).

COOLANT MIXTURE

Engine coolant must be mixed with water to a specific percent. A 100% coolant mixture could cause system overheating or premature system failure. The percentage of coolant to water can vary depending on climate condition, but a 50/50 mixture is a standard percentage. Engine coolant should also include an aluminum protection additive. This will help protect against metal deterioration.

MAINTENANCE

Periodic maintenance is necessary for extended cooling system and engine life. Engine and cooling systems are made of different metals, electrolysis begins to destroy the metals. Changing the coolant at scheduled maintenance periods reduces electrolysis and removes sediment.

Replace coolant at 36 months or 52,500 miles, and every 24 months or 30,000 miles thereafter.

PRESSURE TESTING

Remove radiator cap. Inspect radiator and radiator cap sealing surfaces. Many radiators use plastic filler neck. The sealing surface of this plastic may distort if vehicle has overheated.

Install pressure tester on radiator cap. Increase pressure slowly and observe pressure tester gauge. Replace radiator cap if pressure is not released as specified on radiator cap. (Scheme 1)

Install pressure tester and pressurize cooling system to radiator cap specification. Inspect all hose connections, water pump, radiator and engine for any signs of leakage. Correct any leaks. (Scheme 2)

Release pressure, but leave pressure tester connected. Start and run engine for a few minutes while observing pressure tester. If pressure build up rapidly, a compression leak to cooling system is indicated. Check for possible defective head gasket, improper head bolt torque and cracked cylinder head.

Commercially available testers can be used to identify cylinder compression leaks into cooling system by detecting gasoline fumes (Hydrocarbons) at radiator fill neck.

Testing Radiator Cap. Scheme 1

Pressure Testing Cooling System. Scheme 2

DRAINING

Remove radiator cap. Ensure heater coolant valve (if equipped) is open. Open drain cocks or remove plugs in radiator and engine block. Inspect drained coolant for signs of excessive rust or oily film. Oil contamination of coolant is an indication of defective engine gaskets, leaking automatic transmission (transaxle) cooling lines or engine oil cooler (if equipped). Clean radiator cooling fins as necessary to ensure proper air flow.

FLUSHING

Note. Many vehicles use an aluminum/plastic radiator and aluminum and different alloy materials in engine block, heads and gaskets. Ensure material used for cleaning and flushing is compatible with these materials.

Back flushing is an effective way of removing scale and rust from cooling systems. Radiator and heater core should be isolated when flushing engine to avoid plugging cores with scale and rust. Remove thermostat before flushing engine. If power flush equipment is used, refer to equipment manufacturers operation instructions to avoid cooling system or equipment damage. Replace thermostat after flushing is complete.

REFILLING

Fill radiator with a 50 percent mixture of water and anti-freeze. Install radiator cap to first notch to keep spillage to a minimum. Start and run engine until upper radiator hose warm indicating thermostat is open. Remove radiator cap carefully and add coolant mixture until system is full. Install radiator cap. Fill coolant recovery reservoir to "FULL COLD" mark. (Scheme 3) Run engine until engine temperature stabilizes. Check cooling system for leaks.

Typical Coolant Recovery System. Scheme 3

If vehicle is slow to warm to operating temperature, or overheating is occurring with radiator top hose cooler than lower radiator hose, replace thermostat and check cooling system for leaks.

Using an anti-freeze tester with temperature compensating feature, test anti-freeze for correct mixture. On vehicles using aluminum engine and/or cooling system parts, refer to owners manual for specific information on coolant type and mixture required.

ENGINE COOLANT CAPACITIES

Note. Approximate capacity figures are shown. Capacities may vary 15% due to system variations.

COOLING SYSTEM SPECIFICATIONS

COOLANT REPLACEMENT SCHEDULE

GENERAL MOTORS PASSENGER CAR DESIGNATIONS