GMC SIERRA 1994 Manual page 290

To Add Coolant
If you need more coolant, add the proper mix
at
the
coolant recovery tunk.
A
CAUTION:
Turning the radiator pressure cap when the engine and radiator
are hot can allow steam and scalding liquids to blow out and
burn you badly. With the coolant recovery tank, you will almost
never have to add coolant at the radiator. Never turn the
radiator pressure cap
-
even a little
-
when the engine and
radiator are hot.
Add coolant mix at the recovery tank, but be careful not to spill it.
A
CAUTION:
You can be burned if you spill coolant on hot engine parts.
Coolant contains ethylene glycol, and it will burn if the engine
parts are hot enough. Don't spill coolant on a hot engine.
Adding Coolant -Diesel Engines
The coolant surge tank
is located on the
passenger side at the
rear corner of the
engine compartment.
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