Pontiac 1993 Sunbird Owner's Manual page 166

Adding Coolant
( 2 . 0 ~ ~4 ENGINE)
To Check Coolant
When your engine is cold, the coolant
level should be at FULL COLD or a
little higher. When your engine is warm,
the level should be at FULL COLD or
higher.
Your engine also has a thermostat
housing with a pressure cap. This cap
and the thermostat must be taken out
to add coolant.
To
Add Coolant
If you need more coolant, add the
proper
mix
at the thermostat housing,
but only when the engine is cool.
1.
When the engine is cool, remove the
thermostat housing pressure cap and
the thermostat.
Without pressing down on the
pressure cap, turn it slowly to the
left until it reaches a "stop."
If you hear a hiss, it means there is
still some pressure. Wait for the hiss
to stop. Then press down on the
pressure cap and continue turning it
to the left. Remove the pressure cap.
Take the thermostat out of the housing.
2.
Add the coolant
mix
to the thermostat
housing until the level reaches the
thermostat housing pressure cap seat.
3 . Put in the thermostat. Be sure it is
fully seated.
4.
Put on the thermostat housing pressure
cap. When it's tight, the arrows on the
cap should line up with the radiator
inlet hose on the thermostat housing.
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