DESCRIPTION
The basic liquid cooling system consists of a radiator, water pump, thermostat, cooling fan, radiator pressure cap, heater, and various connecting hoses and cooling passages in the block and cylinder head.
DRAINING
Remove radiator cap and open heater control valve to maximum heat position. Open radiator and engine block drain plugs. In-line engines usually have one drain plug, located at left rear of cylinder block. On "V" type engines, there are 2 drain plugs, one in each bank of cylinders.
CLEANING
A good cleaning solution removes most rust and scales. Follow manufacturer's directions in the use of cleaner. If considerable rust and scale has to removed, cooling system should be flushed. Clean radiator air passages with compressed air.
FLUSHING
| CAUTION | Aluminum and plastic materials are used in radiators. Flushing solution used must be compatible with aluminum. |
- Back flushing is an effective means of removing cooling system rust and scale. The radiator, engine and heater must be flushed separately. In severe cases, the pressure flushing method may be used. Always remove thermostat prior to pressure flushing. Do not back flush systems that have water shut-off valve in heater system, damage to valve can result. Various types of flushing equipment are available. Follow manufacturer's directions carefully.
- To flush radiator, connect flushing gun to water outlet of radiator and disconnect water inlet hose. To prevent flooding engine, attach a hose to radiator inlet. Use air in short bursts to prevent damage to radiator. Continue flushing until water runs clear.
- To flush engine, remove thermostat and replace housing. Connect flushing gun to water outlet of engine. Flush system while using short air bursts until water runs clean. Flush heater core as described for radiator. Ensure heater control valve is set to maximum heat position before flushing heater.
REFILLING
To prevent air from being trapped in engine block, engine should be running when refilling cooling system. After system is full, continue running engine until thermostat is open, then recheck fill level. Do not overfill system.
Scheme 1
- Visually inspect thermostat for corrosion and proper sealing of valve and seat. With thermostat at room temperature, hold thermostat to a light. If light leaks around the thermostat valve, replace thermostat. On some thermostats, slight leakage of light at one to 2 locations on the perimeter of valve may be detected. This should be considered normal.
- To heat test thermostat, immerse thermostat in a boiling solution of 50/50 mixture of coolant and water. (Scheme 1)With solution heated to 221° F (100° C), a 192° F (89° C) thermostat should open 1/8" (3.2 mm).
- With solution heated to 221° F (105° C), a 197° F (92° C) thermostat should open 1/8" (3.2 mm). Replace thermostat if not opening as specified.
PRESSURE TESTING
A pressure tester is used to check both radiator cap and complete cooling system. Test components as follows, following tool manufacturer's instructions.
Radiator Cap
Visually inspect radiator cap, then dip cap into water and connect to tester. Pump tester to bring pressure to upper limit of cap specification. (Scheme 2) If radiator cap fails to hold pressure, replace radiator cap.
Scheme 2
With pressure tester, pressurize radiator to no more than 20 Lbs. If pressure drops, inspect for external leaks. If no leaks are apparent, remove tester and run engine until normal operating temperature is reached. Reinstall tester and observe. If after pumping tester, pressure builds up immediately, a possible leak exists from a faulty head gasket or crack in cylinder head or block.