This vehicle has a pressure-type engine cooling system.
A thermostat controls the coolant circulation.
The cooling system consists of the following components:
| • | A radiator pressure cap (gasoline engines) |
| • | A coolant recovery reservoir (gasoline engines) |
| • | A coolant surge tank and surge tank cap (diesel engines) |
| • | A cooling fan and fan clutch |
| • | A coolant pump and pulley |
A 103 kPa (15 psi) radiator or surge tank cap seals the
cooling system, causing the system to operate at a higher than atmospheric
pressure. The high pressure operation raises the boiling point of the coolant
to about 125°C (257°F), increasing the cooling efficiency of the
radiator.
The pressure-vacuum valve radiator cap, used with gasoline engines,
allows the coolant to expand through the pressure valve in the center of the
cap without building up unnecessary pressure. The expanding coolant flows
into the coolant recovery reservoir and the vent valve closes because of
coolant expansion and flow. Any air in the system is forced into the coolant
recovery reservoir and then out of the vent tube at the top of the reservoir.
As the system cools, vacuum forces the coolant in the reservoir back to
the radiator through the vent valve. Because of this, the radiator remains
full at all times.
The diesel engine uses a cooling system with a surge tank. The pressure
cap for the diesel engine differs from the gasoline engine pressure cap. The
cap is on the surge tank. The diesel engine uses a pressurized surge tank.
Coolant circulates through the surge tank. The surge tank allows the escape
of any air in the system and provides room for coolant expansion when the
coolant is hot.
The cooling system reaches 103 kPa (15 psi) in either
system only after the system reaches normal operating temperature.
Engine Coolant
Notice: Pure coolant 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, as the freeze level rises rapidly after this point.
Pure coolant will freeze at -22°C (-8°F).
This vehicle was manufactured with GM Goodwrench DEX-COOL™.
GM Goodwrench DEX-COOL™ was developed to last for 240 000 km
(150,000 mi) or 5 years, whichever occurs first. Make sure only GM
Goodwrench DEX-COOL™ is used when coolant is added or changed.
When adding DEX-COOL™ to the radiator, add clean, drinkable water
to the cooling system. If you use the old coolant, make sure the solution
is clean and clear, and that the solution is 50/50 mixture of glycol and water.
| | Notice: Pure coolant 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, as the freeze level rises rapidly after this point.
Pure coolant will freeze at -22°C (-8°F).
|
| • | Give freezing protection down to -37°C (-34°F). |
| • | Give boiling protection up to 129°C (260°F). |
| • | Protect against rust and corrosion. |
| • | Help keep the proper engine temperature. |
| • | Allow the warning lights and gauges to work correctly. |
Uncommon Cooling System Problems
Problems not requiring disassembly of the cooling system:
| • | Large obstructions that block the radiator or the air conditioning
condenser; The following are some examples of large obstructions: |
| - | Front mounted bike carriers |
| - | Front mounted tire carriers |
| • | Missing or damaged air baffle or lower air deflector |
Problems requiring disassembly of the cooling system:
| • | An incorrect or damaged fan |
| • | Faulty emission system components (could cause overheating at
idle) |
| • | Positive Crankcase Ventilation (PCV) valve |
| • | Pressure testing the cooling system with the radiator cap installed |
| • | Plugged or incorrect radiator |
| • | The cylinder head gasket |
| • | A damaged intake manifold or intake manifold gasket |
| • | Plugged coolant passages in the cylinder head(s) |
| • | An incorrect thermostat that has been installed |
