Cadillac 2000 Catera Owner's Manual page 228

CAUTION:
Steam and scalding liquids from a hot cooling
system can blow out and burn you badly. They
are under pressure, and if you turn the coolant
-- --
surge tank pressure cap even a little they
can come out at high speed. Never turn the cap
when the cooling system, including the coolant
surge tank pressure cap, is hot. Wait for the
cooling system and coolant surge tank pressure
cap to cool if you ever have to turn the
pressure cap.
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