XQ125 Generator Set Caterpillar

• DEAC ____________________Diesel Engine Antifreeze Coolant

Clean the cooling system and flush the cooling system before the recommended maintenance interval if the following conditions exist:

• The engine overheats frequently.

• Foaming is observed.

• The oil has entered the cooling system and the coolant is contaminated.

• The fuel has entered the cooling system and the coolant is contaminated.

Note: Inspect the water pump and the water temperature regulator after the cooling system has been drained. This inspection is a good opportunity to replace the water pump, the water temperature regulator, and the hoses, if necessary.

Drain

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Pressurized System: Hot coolant can cause serious burns. To open the cooling system filler cap, stop the engine and wait until the cooling system components are cool. Loosen the cooling system pressure cap slowly in order to relieve the pressure.

1. Stop the engine and allow the engine to cool. Loosen the cooling system filler cap slowly to relieve any pressure. Remove the cooling system filler cap.

   Note: Refer to Operation and Maintenance Manual, "General Hazard Information" for information on Containing Fluid Spillage.

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   Illustration 1	g03423123
   Typical example

2. Remove drain plug (1) on the engine. Also remove the drain plug (2). Open the drain cock or remove the drain plug on the radiator.

   Allow the coolant to drain into a suitable container.

3. Properly dispose of the drained material. Obey local regulations for the disposal of the material.

Flush

1. Flush the cooling system with clean water and a suitable cleaning agent to remove any debris. Refer to your Cat dealer for suitable cleaning agents.

2. Install connection hose. Clean the drain plugs. Install the drain plugs. Tighten drain plug securely.
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   NOTICE
   Do not fill the cooling system faster than 5 L (1.3 US gal) per minute to avoid air locks. Cooling system air locks may result in engine damage.

3. Fill the cooling system with clean water and install the cooling system filler cap.

4. Start and run the engine at low idle for a minimum of 30 minutes. The coolant temperature should be at least 82 °C (180 °F).
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   NOTICE
   Improper or incomplete rinsing of the cooling system can result in damage to copper and other metal components. To avoid damage to the cooling system, make sure to completely flush the cooling system with clear water. Continue to flush the system until all signs of the cleaning agent are gone.

5. Stop the engine and allow the engine to cool. Loosen the cooling system filler cap slowly to relieve any pressure. Remove the cooling system filler cap. Remove the connection hose or remove the cooling system drain plugs. Allow the water to drain. Flush the cooling system with clean water. Install the connection hose.

6. The drain plug O rings on the engine block must be replaced. Clean the drain plugs and install new O ring seal. Install the drain plugs and tighten to a torque of 35 N·m (25 lb ft).

Fill

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NOTICE
Do not fill the cooling system faster than 5 L (1.3 US gal) per minute to avoid air locks. Cooling system air locks may result in engine damage.

1. Fill the cooling system with the coolant/antifreeze. Refer to this Operation and Maintenance Manual, "Refill Capacities and Recommendations" topic (Maintenance Section) for more information on cooling system specifications. Do not install the cooling system filler cap.

2. Start and run the engine at low idle. Increase the engine rpm to high idle. Operate the engine to open the engine thermostat. This operation will allow any air in the system to be purged. Decrease the engine speed to low idle. Stop the engine.

3. Maintain the coolant level at the maximum mark that is correct for your application.

4. Clean the cooling system filler cap. Inspect the gasket that is on the cooling system filler cap. If the gasket that is on the cooling system filler cap is damaged, discard the old cooling system filler cap and install a new cooling system filler cap. If the gasket that is on the cooling system filler cap is not damaged, perform a pressure test. If the cooling system filler cap does not retain the correct pressure, install a new cooling system filler cap.

5. Start the engine. Inspect the cooling system for leaks and for the correct operating temperature.