Cooling System. Buick Roadmaster 1996

For 1990-2009 cars

### General Description

The 3 types of cooling systems in this model are the base, the extra-capacity and the heavy-duty cooling systems.

The base cooling system consists of the following components:

• | An aluminum core

• | Plastic end tanks

• | A pressurized coolant recovery reservoir

• | A gear-driven engine coolant pump

• | A thermostat

• | Two electric, motor-driven fans

The right-hand end tank of the radiator contains a transmission oil cooler.

The extra-capacity cooling system (RPO VO3) consists of the same components as the base cooling system, with the addition of a larger left-hand end tank and a larger motor in the left-hand electric motor-driven fan. The larger left-hand radiator end tank allows for an engine oil cooler, within the end tank itself.

The heavy-duty cooling system (RPO VO8) consists of the same components as the extra-capacity cooling system, except that a belt-driven fluid clutch-controlled fan replaces the right-hand electric motor-driven cooling fan. The engine-to-radiator coolant hoses, on the heavy-duty cooling system, have metal sections to protect the hoses from the belt-driven fan blades.

The coolant pump takes the engine coolant from the suction side of the radiator, through the thermostat (when open), and through the internal passages in the cylinder heads and the engine block. The heated coolant is then directed back to the radiator. A separate coolant flow loop from the coolant pump, through the hoses, to the heater core and back to the coolant pump, provides the passenger compartment with heat and defrost.

The cooling system uses a pressurized coolant recovery reservoir in order to ensure that the radiator hoses and the engine coolant passages are completely full at all normal operating temperatures. When the system is cool, add coolant to the coolant recovery reservoir.

### Engine Coolant

This vehicle has a newly developed engine coolant. GM Goodwrench DEX-COOL™ was developed to last for 166 000 km (100,000 mi) or 5 years, whichever occurs first. Follow the instructions in Draining/Filling Cooling System. Make sure only GM Goodwrench DEX-COOL™ (orange-colored, silicate-free) is used when coolant is added or changed.

A 50/50 mixture of ethylene glycol (GM Goodwrench DEX-COOL™) and water will provide the following protection:

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.

• | Let the warning lights and gauges work correctly.

### Low Coolant Level Switch

The low coolant level switch is on the bottom of the coolant recovery reservoir. When the coolant is below the recommended level, the switch contacts close, using a magnetic float, and a indicator lamp illuminates in the instrument cluster.

### Engine Coolant Temperature Switch

The engine coolant temperature switch activates a indicator lamp in the instrument cluster if the engine temperature exceeds 126°C (250°F).

### Engine Coolant Temperature Sensor

The engine coolant temperature sensor is on the lower front section of the coolant pump. The sensor provides a variable input, according to the engine coolant temperature to the Powertrain Control Module (PCM).

### Throttle Body Heater

The flow of engine coolant to the throttle body improves cold weather driveablility. The engine coolant routes from the rear of both cylinder heads to the throttle body and then to the coolant recovery reservoir.

### Radiator Air Side Baffles and Deflectors

Radiator air side baffles, on both sides of the radiator, increase the air flow through the radiator. Radiator air deflectors are on the lower sides, and at the bottom of the radiator.

### Fan Belt (RPO V08 Heavy-Duty Cooling System)

An additional fan belt drives the optional mechanical cooling fan. The driving pulley bolts to the crankshaft balancer, and the driven pulley bolts to the fan clutch. A tensioner pulley maintains the proper belt tension on the driving and driven pulleys.

### Cylinder Block Drains

The engine cylinder block has 2 threaded drain holes on either side of the engine block, just above the oil pan. Knock sensors are in both drain holes.