This topic reviews the importance of cooling system maintenance and the impact on the engine EGR cooler.

With the introduction of engine exhaust gas re circulation (EGR) and its associated engine hardware, Performing proper coolant fill procedures and system pressure checks are extremely important to lengthening EGR cooler and engine life.

The EGR cooler is subjected to the highest coolant temperatures and the most rapid temperature changes of the cooling system. If localized boiling occurs within the EGR cooler, an internal coolant leak can result. Air pockets in the system caused by improper coolant fill practices can lead to premature failure of the EGR cooler.

Be observant when filling an engine with coolant. Depending on the coolant system, there could be special fill instructions. Watch for information decals or tags for special instructions when filling an engine with coolant. These instructions can be located anywhere on the cooling system (surge tank, radiator tank, radiator mount, firewall, etc.). If no special instructions are present, search for a manual bleed valve on the upper radiator pipe and open this valve during the coolant fill process. This manual bleed valve allows trapped air to escape during the fill process. Not all applications have this valve.

Coolant fill procedure: 

Remove the pressure 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.
• Open all coolant flow valves to equipment heating systems. See the OEM service manual for valve locations.
• Wait 2 to 3 minutes, without starting the engine, to allow the coolant level to stabilize.
• Add a 50/50 mixture to bring the coolant 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 pressure cap off:

• Operate the engine at LOW idle for 2 minutes.
• Turn the engine OFF and add coolant to bring the level back to FULL, using a 50/50 mixture.

With the pressure cap off:

• Operate the engine at LOW idle for 1 minute to allow adequate oil pressure to build throughout the engine.
• Run the engine at HIGH idle until the thermostat opens.

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

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

If any drained coolant remains after filling, there is an air pocket in the system which must be purged. Allow the engine to reach operating temperature and top off the system with coolant. Proper fill and dearation of the system is critical to EGR cooler life.

The coolant pressure cap and the system’s ability to hold the minimum pressure must be checked whenever an EGR cooler is replaced and should be part of your cooling system maintenance practice. This check is important, due to the complexity of the coolant system since the introduction of EGR.

Your Routine Maintenance Should Include a Pressure Test of the Cooling System

The radiator cap must hold a coolant system pressure of 15 psi, 

(15 psi is the requirement for all Cummins EGR engines)

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