Cooling System
This vehicle has a pressure-type engine cooling system. The system has
thermostatic control of the coolant circulation. The cooling system is sealed
by a pressure type radiator cap. The cap causes the system to operate at
a pressure higher than atmospheric pressure. The high-pressure operation
raises the boiling point of the coolant, which increases the cooling efficiency
of the radiator. The 104 kPa (15 psi) pressure cap raises the
boiling point of the coolant to about 125°C (257°F) at sea level.
Engine Coolant
Notice: Antifreeze can be added to raise the boiling point of the
coolant, but too much will affect the freezing point. Do not use a solution
stronger than 70 percent antifreeze, as the freeze level rises rapidly
after this point. Pure antifreeze will freeze at -22°C (-8°F).
This vehicle has a newly developed engine coolant. GM Goodwrench
DEX-COOL™ is developed to last for 240,000 km (150,000 miles)
or five years, whichever occurs first. Use only DEX-COOL™ when coolant
is added or changed.
A 50/50 mixture of ethylene glycol (DEX-COOL™) and water provides
the following protection:
| • | Gives freeze protection down to -37°C (-34°F) |
| • | Gives boiling protection up to 129°C (265°F) |
| • | Protects against rust and corrosion |
| • | Helps maintain the proper engine temperature |
Coolant Recovery Reservoir (Gasoline Engines Only)
Notice: When adding coolant, it is important that you use GM Goodwrench DEX-COOL™
coolant meeting GM Specification 6277M. If silicated coolant
is added to the system, premature engine, heater core or radiator corrosion
may result. In addition, the engine coolant will require change sooner --
at 50 000 km (30,000 miles) or 24 months.
A coolant recovery reservoir is used on all P model vehicle
that are equipped with a gasoline engine. A see-through plastic reservoir
connects to the radiator by a vent hose. As the vehicle is driven, the coolant
heats and expands. The portion of the fluid that is displaced by this expansion
flows from the radiator into the coolant recovery reservoir. When the vehicle
stops and the coolant cools and contracts, vacuum draws the displaced coolant
back into the radiator. Thus the radiator is filled with the desired level
of coolant at all times. This results in increased cooling efficiency.
Keep the coolant level between the ADD and the FULL marks on the recovery
reservoir. These marks are about one liter (one quart) apart. Use a 50/50
mixture of ethylene glycol antifreeze (DEX-COOL™) and distilled water
in order to keep the system at the FULL mark when the reservoir is hot.
Uncommon Cooling System Problems
The following problems do not require disassembly of the cooling system:
| • | Remove large obstructions that block the radiator or the condenser. |
| - | The auxiliary oil cooler |
| - | Ice, mud or snow obstructs the grille |
| • | The engine oil is overfilled. |
| • | Loose, damaged or missing air seals |
| • | A missing or damaged lower air baffle |
| • | Incorrect ignition timing |
The following problems do require disassembly of the cooling system:
| • | An incorrect or damaged fan |
| • | Worn or damaged emission system components that could cause overheating
at idle: |
| - | Damaged Positive Crankcase Ventilation (PCV) valve |
| - | Thermal Vacuum Valve (TVV) |
| - | Engine Coolant Temperature sensor (ECT) |
| • | Incorrect radiator for the application |
| | Check the specifications for the correct part number. |
| • | Pressure check the cooling system while the pressure cap is installed.
This shows if the pressure cap leaks due to radiator filler neck damage. |
| • | Worn or damaged water pump |
| - | The impeller vanes are eroded or broken. |
| - | The bearing or the seal is worn or damaged. Check the shaft for
bearing play. |
| • | Plugged radiator tubes. Perform a flow check. |
| - | The cylinder head gasket |
| - | The intake manifold gasket |
| • | Plugged coolant passages in the cylinder heads. Do a visual check. |
