Pontiac 1999 Montana Owner's Manual page 291

6. Then replace the pressure cap. At any time during
this procedure if coolant begins to flow out of the
filler neck, reinstall the pressure cap. Be sure the
arrows on the pressure cap line up like this.
7. Then fill the coolant recovery tank to the
FULL COLD mark.
8. Put the cap back on the coolant recovery tank.
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