19291-ZW1-000 Honda VALVE, RELIEF (Honda Code 4898276).

Keep all parts clean from contaminants.Contaminants may cause rapid wear and shortened component life.
Clean the cooling system and flush the cooling system before the recommended maintenance interval if the following conditions exist:
The engine overheats frequently.
Foaming of the coolant 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: When the cooling system is cleaned, only clean water is needed when the ELC is drained and replaced.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
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.
Stop the engine and allow the engine to cool. Loosen the cooling system filler cap slowly in order to relieve any pressure. Remove the cooling system filler cap.
Illustration 1 g03349949
Typical example
Open the drain cock or remove the drain plug (1) on the engine. Open the drain cock or remove the drain plug on the radiator. Allow the coolant to drain.
Dispose of used engine coolant or recycle. Various methods have been proposed to reclaim used coolant for reuse in engine cooling systems. The full distillation procedure is the only method acceptable by Caterpillar to reclaim the coolant.
For information regarding the disposal and the recycling of used coolant, consult your Cat dealer Flush
Flush the cooling system with clean water in order to remove any debris.
Close the drain cock or install the drain plug in the engine. Close the drain cock or install the drain plug on the radiator.
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.
Fill the cooling system with clean water. Install the cooling system filler cap.
Start and run the engine at low idle until the temperature reaches 49 to 66 °C (120 to 150 °F).
Stop the engine and allow the engine to cool. Loosen the cooling system filler cap slowly in order to relieve any pressure. Remove the cooling system filler cap. Open the drain cock or remove the drain plug on the engine. Open the drain cock or remove the drain plug on the radiator. Allow the water to drain. Flush the cooling system with clean water. Fill
Close the drain cock or install the drain plug on the engine. Close the drain cock or install the drain plug on the radiator.
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.
Fill the cooling system with Extended Life Coolant (ELC). Refer to the Operation and Maintenance Manual, "Fluid Recommendations" for more information on cooling system specifications. Do not install the cooling system filler cap.
Start and run the engine at low idle. Increase the engine rpm to high idle. Run the engine at high idle for 1 minute in order to purge the air from the cavities of the engine block. Decrease the engine speed to low idle. Stop the engine.
Check the coolant level. Maintain the coolant level within 13 mm (0.5 inch) below the bottom of the pipe for filling. Maintain the coolant level in the expansion bottle (if equipped) at the correct level.
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Filler cap
Clean the cooling system filler cap and inspect the gasket. If the gasket is damaged, discard the old filler cap and install a new filler cap. If the gasket is not damaged, use a 9S-8140 Pressurizing Pump in order to pressure test the filler cap. The correct pressure is stamped on the face of the filler cap. If the filler cap does not retain the correct pressure, install a new filler cap.
Start the engine. Inspect the cooling system for leaks and for correct operating temperature.