Chevrolet 2007 Kodiak Owner's Manual page 286

Checking Coolant
The coolant surge tank is located in the engine
compartment on the driver's side of the vehicle.
286
CAUTION:
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Turning the surge tank pressure cap when
the engine and radiator are hot can allow
steam and scalding liquids to blow out
and burn you badly. Never turn the surge
tank pressure cap — even a little — when
the engine and radiator are hot.
The vehicle must be parked on a level surface.
When your engine is cold, the coolant level should
be at the FULL COLD mark or higher.