A water rush or gurgle sound from the heater core at the center of the instrument panel on some 2015-2019 Colorado and Canyon models may be caused by air ingestion in the cooling system.
If the water rush or gurgle sound is heard, replace the radiator surge tank (Fig. 15) on vehicles from Start of Production (SOP) to the VIN breakpoint listed in Bulletin #19-NA-007. 2019 and later model year vehicles produced after the VIN breakpoint already have the new surge tank.
Fig. 15
Add Coolant Over the Factory Fill Line
When filling the surge tank after installation of a new tank or if the water sound is heard on a vehicle with a new tank, check the coolant level. The coolant in the surge tank should be 150 ml over the factory fill line, as shown. (Fig. 16)
Fig. 16
In some circumstances, it may be difficult to remove the air from the heater core using the Vac-N-Fill method because the radiator cap and heater core are at about the same height. If the sound persists, raise the front of the vehicle with a hoist until the radiator cap is above the cowl after adding the additional coolant to the surge tank. Remove the radiator cap and run the engine for an hour. Run the throttle up to approximately 1500 RPM three or four times during the hour.
For more information, refer to Bulletin #19-NA-007.
– Thanks to Matt Singer
