Buick RIVIERA 1993 Manual page 200

When you decide it's safe to lift the hood, here's what
you'll see:
Coolant recovery tank
Radiator pressure cap
Electric engine fan
An electric fan under the hood can start up even
when the engine is not running and can injure
you. Keep hands, clothing and tools away from
any underhood electric fan.
I
If the coolant inside the coolant recovery tank is boiling,
don't do anything else until it coals down.
The coolant level should be at or above "FULL COLD."
If it isn't, you may have a leak in the radiator hoses,
heater hoses, radiator, water pump or somewhere else in
the cooling system.
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