Mack Truck RD688S

Warning! Avoid injury when checking coolant in a hot engine. Wait for the engine to cool prior to checking the level, whenever possible.

Turn the radiator cap counterclockwise to the first stop but do NOT depress it.

After the pressure has completely dissipated, press the cap downward and continue turning to remove it.

The AD6 model chassis has both a pressurized surge tank and a non-pressurized plastic coolant recovery bottle, where quick checks of coolant level can be made and additional coolant can be added to the system.

The recovery bottle is located in the engine compartment, mounted on the left-hand cab firewall bracket. Coolant should be visible between the indicator lines on the bottle.

Periodically, the coolant level should be checked by observing the coolant in the pressurized coolant surge tank. The coolant surge tank is located directly above the coolant recovery bottle. The surge tank should always be full of coolant.

The RDB and RB model chassis do not have a coolant recovery bottle. Coolant is checked by removing the radiator fill cap and observing if coolant is visible one inch below the base of the radiator filler neck.;

Warning: This maintenance check requires trained personnel with PPE!

General check for cooling system leaks

Inspect hoses and clamps for leaks and overall condition

Degree of antifreeze concentration

Is a MACK-approved winterfront used?

CAUTION! Use only a MACK-approved winterfront designed for the specific chassis.

CAUTION! Never close the winterfront if equipped with a viscous fan drive.

CAUTION! Winterfronts are NOT RECOMMENDED for vehicles that only operate intermittently in cold climates.

CAUTION! If using a coolant other than that specified by Mack Trucks, Inc., it is the responsibility of the customer to determine and perform the proper coolant maintenance procedures. Refer to the Maintenance and Lubrication Manual, T5494, for antifreeze specifications.

Filled with the proper coolant mixture

Engine run with the radiator cap tight until operating temperature is reached and the thermostat opens

Engine run long enough to ensure the system is free of air and has the correct amount of coolant

Sign off on the cooling system refilling

Electrical Accessory Connection Points

This MACK chassis is ready for convenient installation of electrical accessories.

Use only the designated CB jacks on the dashboard, or the following connection points available on the electrical equipment panel:

Buffered tachometer (RPM) output

Buffered speedometer (MPH) output

Each connection point is described below.

Warning: This inspection requires trained personnel with PPE!

Inspect the wheels and cap nuts for any signs of looseness

Look for cracks around the hand hole, stud hole, and wheel

Check for broken studs, wheel damage, or improperly seated lock rings

DANGER! Tires used on multi-piece rims must be assembled and inflated only by experienced, qualified personnel

Tires must be inflated in a safety cage whenever possible

The tire must be deflated prior to removal of the tire-and-rim assembly from the vehicle

DANGER! NEVER position your body in front of the rim during inflation

CAUTION! NEVER use water-based sealants, puncture-proofing compounds, or liquid balancing materials containing water in aluminum radial ply truck tires