ISBe/ISB Series Engines – 008-018   Cooling System

WARNING  Do not remove the pressure cap from a hot engine. Wait until the coolant temperature is below 50°C [120°F] before removing the pressure cap. Heated coolant spray or steam can cause personal injury.

NOTE: Never use a sealing additive to stop leaks in the coolant system. This can result in coolant system plugging and inadequate coolant flow, causing the engine to overheat.

The engine coolant level must be checked daily.

CAUTION  Do not add cold coolant to a hot engine. Engine castings can be damaged. Allow the engine to cool below 50°C [120°F] before adding coolant.

NOTE: In the event of a water pump or EGR cooler failure, it is recommended that coolant level switches be checked for operation. Consult the OEM service manual for operational checks and repairs.

On applications that use a coolant recovery system, check to make sure the coolant is at the appropriate level in the coolant recovery tank for the engine temperature.

Many coolant recovery/expansion tanks, also called “top tanks”, have sight glasses (1) or are made of a clear material (not shown) to aid in checking the coolant level (2) without removing the radiator cap.

It is important to understand the impact of temperature on the expansion of the coolant. Most “top tanks” do not have a provision for a “FULL HOT” coolant level. Filling the “top tank” while hot will result in a low operating level once the system has cooled.

Fill the cooling system with coolant to the bottom of the fill neck in the radiator fill or recovery/expansion tank.

NOTE: Some radiators have two fill necks, both of which must be filled when the cooling system is drained.

WARNING  Do not remove the pressure cap from a hot engine. Wait until the coolant temperature is below 50°C [122°F] before removing the pressure cap. Heated coolant spray or steam can cause personal injury.

Isolate the engine from the vehicle cooling system by closing coolant flow valves to the equipment heating systems before initiating repair. This will prevent the heater circuit from draining, minimizing the chance for air pockets to be present during the fill process.

This air can be very difficult to purge in some applications that have several feet of plumbing and multiple heater cores.

NOTE: If the coolant is being changed, or if the cooling system is being flushed, it is desirable to leave the coolant flow valves to the equipment heating systems open, in order to completely drain the system.

Use the OEM service manual for any special coolant drain and fill requirements.

These special instructions can also be located near the cooling system access or fill door on the vehicle.

Remove the radiator/expansion tank cap to allow the coolant to drain completely.

WARNING  Coolant is toxic. Keep away from children and pets. If not reused, dispose of in accordance with local environmental regulations.

Drain the cooling system by opening the drain valve on the radiator and removing the plug in the bottom of the water inlet. A drain pan with a capacity of 19 liters [5 gal] will be adequate for most applications.

Check for damaged hoses and loose or damaged hose clamps. Replace as required. Check the radiator for leaks, damage, and buildup of dirt. Clean and replace as required.

After the cooling system is completely drained, close the drain valves. Refer to the OEM service manual for complete cooling system drain information.

CAUTION  The system must be filled properly to prevent air locks or serious engine damage can result. During filling, air must be vented from the engine coolant passages. Wait 2 to 3 minutes to allow air to be vented; then add mixture to bring the level to the top.

To vent air during the fill process:

• Some thermostats have check balls that allow air to vent through the thermostat when closed.
• An air vent port connection, which connects to the top tank/coolant recovery tank of the cooling system, is located next to the water outlet.

This provides adequate venting for a fill rate of 19 liters [5 gal] per minute.

NOTE: An alternate to using sodium carbonate, as outlined in this procedure, is to use Restore™.

Restore™ is a heavy-duty cooling system cleaner that removes corrosion products, silica gel, and other deposits. The performance of Restore™ is dependent on time, temperature, and concentration levels. An extremely scaled or flow-restricted system, for example, can require higher concentrations of cleaners, higher temperatures, longer cleaning time, or the use of Restore Plus™. Up to twice the recommended concentration levels of Restore™ can be used safely. Restore Plus™ must be used only at its recommended concentration level. Extremely scaled or fouled systems can require more than one cleaning.

WARNING  Coolant is toxic. Keep away from children and pets. Dispose of in accordance with local environmental regulations.

WARNING  Do not stand near surge tank or radiator while operating engine with pressure cap off. If the vehicle is equipped with a fill door on side of surge tank, keep it closed due to coolant expansion.

CAUTION  Do not operate engine with the pressure cap off at temperatures above 200 degrees F. This can result in potential engine damage by cavitation of the water pump and localized boiling.

CAUTION  Before topping off coolant, allow the system temperature to cool to ambient. This will ensure that an adequate amount of coolant is available to the water pump during all periods of operation.

CAUTION  Do not relieve the system pressure while hot in order to “top off” immediately before returning the vehicle to service. The system will not be able to generate the pressure through the expansion of the coolant necessary for operation. This can result in potential engine damage by cavitation of the water pump and localized boiling.

Fill the cooling system with a mixture of sodium carbonate and water (or a commercially available equivalent) to the capacity or level stated in the OEM service manual.

NOTE: Adequate venting is provided for a fill rate of 19 liters [5 gal] per minute.

Unless indicated otherwise by the OEM instructions, it is critical that all shutoff valves be returned to their open positions once the system has been refilled and the deaeration process is about to begin. This will help to make sure as much air as possible will be purged from the cooling system. See the OEM service manual for valve locations.

Wait 2 to 3 minutes without starting the engine, to allow the system to naturally purge entrained air and the coolant level to stabilize.

Add plain water to bring the level back to FULL.

Turn all cab heater switches to HIGH in order to allow maximum coolant flow through heater core(s). The blower does not have to be on.

With the radiator or pressure cap off:

• Operate the engine at LOW Idle for 2 minutes.
• Turn off the engine and add plain water to bring the level back to FULL.

With the radiator or pressure cap off:

• Start the engine.

NOTE: After starting a cold engine, increase the engine speed (rpm) slowly to provide adequate lubrication to the bearings and to allow the oil pressure to stabilize.

Allow the engine to idle 2 minutes before shutting it down. This allows adequate cool down of pistons, cylinders, bearings, and turbocharger components.

Turn off the engine and check the coolant level according to the OEM service manual recommendations and add, if necessary, to bring it back to the FULL level.

Install the radiator or pressure cap.

Operate the engine for 1 to 1½ hours with the coolant temperature above 80°C [176°F].

Shut the engine off. Allow the coolant temperature to drop to 50° C [122° F] before draining the cooling system.

Drain the cooling system.

WARNING  Do not stand near surge tank or radiator while operating engine with pressure cap off. If the vehicle is equipped with a fill door on side of surge tank, keep it closed due to coolant expansion.

CAUTION  Do not operate the engine with the pressure cap off a temperature above 93°C [200°F]. This can result in potential engine damage by cavitation of the water pump and localized boiling.

NOTE: Do not install the radiator cap.

Fill the cooling system with good quality water to the capacity or level stated in the OEM service manual.

Unless indicated otherwise by OEM instructions, it is critical that all shutoff valves be returned to their open positions once the system has been refilled and the deaeration process is about to begin. This will help to make sure as much air as possible will be purged from the cooling system. See the OEM service manual for valve locations.

Wait 2 to 3 minutes, without starting the engine, to allow the system to naturally purge entrained air and the coolant level to stabilize.

Add plain water to bring the level back to FULL.

Turn all cab heater switches to HIGH in order to allow maximum coolant flow through heater core(s).

With the radiator or pressure cap off:

• Operate the engine at LOW Idle for 2 minutes.
• Turn off the engine and add plain water to bring the level back to FULL.

With the radiator or pressure cap off:

NOTE: After starting a cold engine, increase the engine speed (rpm) slowly to provide adequate lubrication to the bearings and to allow the oil pressure to stabilize.

• Start the engine.

Allow the engine to idle 2 minutes before shutting it down. This allows adequate cool down of pistons, cylinders, bearings, and turbocharger components.

Shut the engine off, allow the cooling system to to cool to 50°C [122°F].

Drain the cooling system.

NOTE: If the water being drained is still dirty, the system must be flushed again until the water is clean.

CAUTION  The system must be filled properly to prevent air locks or serious engine damage can result. During filling, air must be vented from the engine coolant passages. Wait 2 to 3 minutes to allow air to be vented; then add mixture to bring the level to the top.

To be sure air is vented during the fill process:

• Some thermostats have check balls that allow air to vent through the thermostat when the thermostat is closed.
• An air vent port connection, which connects to the top tank/coolant recovery tank of the cooling system, is located next to the water outlet.

The system has a designed fill rate of 19 liters [5 gal] per minute.

CAUTION  Never use water alone for coolant. Damage from corrosion can be the result of using water alone for coolant.

For engine coolant specifications. Refer to Cummins® Coolant Requirements and Maintenance, Bulletin 3666132.

WARNING  Do not remove the pressure cap from a hot engine. Wait until the coolant temperature is below 50°C [122°F] before removing the pressure cap. Heated coolant spray or steam can cause personal injury.

WARNING  Do not stand near surge tank or radiator while operating engine with pressure cap off. If the vehicle is equipped with a fill door on side of surge tank, keep it closed due to coolant expansion.

CAUTION  Do not operate the engine with the pressure cap off a temperature above 93°C [200°F]. This can result in potential engine damage by cavitation of the water pump and localized boiling.

CAUTION  Topping off the system while hot is not recommended when using the fill door on transit bus applications equipped with surge tanks. Bringing the level to the bottom of the door while the system is hot will not provide adequate volume of coolant for lower operating temperatures. This can result in cavitation of the water pump and greatly increase the potential for engine damage.

CAUTION  Before topping off coolant, allow the system temperature to cool to ambient. This will ensure that an adequate amount of coolant is available to the water pump during all periods of operation.

CAUTION  Do not relieve the system pressure while hot in order to “top off” immediately before returning the vehicle to service. The system will not be able to generate the pressure through the expansion of the coolant necessary for operation. This can result in potential engine damage by cavitation of the water pump and localized boiling.

Remove the radiator or fill cap.

Fill the cooling system to the capacity or level stated in the OEM service manual, using a mixture of 50 percent water and 50 percent ethylene glycol or propylene glycol antifreeze.