See Figure 1
The coolant level should be maintained about 1 / 2 in. (13mm) below the filler neck of the radiator with 4L-134, 4F-134, 6-226 and 6-230 engines.
On the 6-225 engine, the coolant level should be maintained 1 1 / 2 -2 in. (38-51mm) below the bottom of the filler cap when the engine is cold. Since operating temperatures reach as high as 205°F (96°C), coolant could be forced out of the radiator if it is filled too high. The radiator coolant level should be checked regularly, such as every time you refuel the vehicle. Never open the radiator cap of an engine that hasn't had sufficient time to cool or the pressure can blow off the cap and send out a spray of scalding water.
On systems with a coolant recovery tank, maintain the coolant level at the level marks on the recovery bottle.
For best protection against freezing and overheating, maintain an approximate 50% water and 50% ethylene glycol (or other suitable) antifreeze mixture in the cooling system. Do not mix different brands of antifreeze to avoid possible chemical damage to the cooling system.
Avoid using water that is known to have a high alkaline content or is very hard, except in emergency situations. Drain and flush the cooling system as soon as possible after using such water.
Never add cold water to an overheated engine while the engine is not running.
After filling the radiator, run the engine until it reaches normal operating temperature, to make sure that the thermostat has opened and all the air is bled from the system.
DRAINING, FLUSHING AND REFILLING
See Figures 2, 3 and 4
To drain the cooling system, allow the engine to cool down BEFORE ATTEMPTING TO REMOVE THE RADIATOR CAP . Then turn the cap until it hisses. Wait until all pressure is off the cap before removing it completely.
- At the dash, set the heater TEMP control lever to the fully HOT position.
- With the radiator cap removed, drain the radiator by loosening the petcock at the bottom of the radiator. Locate any drain plugs in the block and remove them. Flush the radiator with water until the fluid runs clear.
- Close the petcock and replace the plug(s), then refill the system with a 50/50 mix of ethylene glycol or other suitable antifreeze. Fill the system to 3 / 4 -1 1 / 4 in. (19.05-31.75mm) from the bottom of the filler neck. Reinstall the radiator cap.
If equipped with a fluid reservoir tank, fill it up to the MAX level.
- Operate the engine at 2,000 rpm for a few minutes and check the system for signs of leaks.
Allow the engine to cool sufficiently before attempting to remove the radiator cap. Use a rag to cover the cap, then remove by pressing down and turning counterclockwise to the first stop. If any hissing is noted (indicating the release of pressure), wait until the hissing stops completely, then press down again and turn counterclockwise until the cap can be removed.
Check the condition of the radiator cap gasket and seal inside of the cap. The radiator cap is designed to seal the cooling system under normal operating conditions which allows the build up of a certain amount of pressure (this pressure rating is stamped or printed on the cap). The pressure in the system raises the boiling point of the coolant to help prevent overheating. If the radiator cap does not seal, the boiling point of the coolant is lowered and overheating will occur. If the cap must be replaced, purchase the new cap according to the pressure rating which is specified for your vehicle.
Prior to installing the radiator cap, inspect and clean the filler neck. If you are reusing the old cap, clean it thoroughly with clear water. After turning the cap on, make sure the arrows align with the overflow hose.