Cadillac XT6 Owner Manual (GMNA-Localizing-U.S./Canada-14574701) -
2021 - CRC - 2/8/21
318 VEHICLE CARE
Check to see if coolant is visible in the
coolant surge tank. If the coolant
inside the coolant surge tank is
boiling, do not do anything else until
it cools down. If coolant is visible but
the coolant level mark is not at or
above the indicated mark, add a 50/
50 mixture of clean, drinkable water
and DEX-COOL coolant. Be sure the
cooling system is cool before this is
done. SeeEngine Overheating 0320.
The coolant surge tank is in the
engine compartment on the driver
side of the vehicle. See Engine
Compartment Overview 0308.
How to Add Coolant to the
Surge Tank
{Warning
Spilling coolant on hot engine parts
can burn you. Coolant contains
ethylene glycol and it will burn if
the engine parts are hot enough.
{Warning
Steam and scalding liquids from a
hot cooling system are under
pressure. Turning the pressure cap,
even a little, can cause them to
come out at high speed and you
could be burned. Never turn the cap
when the cooling system, including
the pressure cap, is hot. Wait for
the cooling system and pressure
cap to cool.
Caution
Failure to follow the specific
coolant fill procedure could cause
the engine to overheat and could
(Continued)
Caution (Continued)
cause system damage. If coolant is
not visible in the surge tank,
contact your dealer.
The coolant surge tank pressure cap
can be removed when the cooling
system, including the surge tank
pressure cap and upper radiator hose,
is no longer hot.
Coolant Fill Instructions (3.6L
Engine Only)
1. Turn the pressure cap slowly counterclockwise. If a hiss is heard,
wait for that to stop. A hiss means
there is still some pressure left.
2. Keep turning the pressure cap slowly and remove it.
Cadillac XT6 Owner Manual (GMNA-Localizing-U.S./Canada-14574701) -
2021 - CRC - 2/8/21
VEHICLE CARE 319
3. Fill the coolant surge tank with theproper mixture to the mark pointed
to on the front of the coolant
surge tank.
4. With the coolant surge tank pressure cap off, start the engine
and let it run until you can feel the
upper radiator hose getting hot.
Watch out for the engine cooling
fans. By this time, the coolant level
inside the coolant surge tank may
be lower. If the level is lower, add
more of the proper mixture to the
coolant surge tank until the level
reaches the mark pointed to on the
front of the coolant surge tank. 5. Replace the pressure cap tightly.
6. Verify coolant level after the engine
is shut off and the coolant is cold.
If necessary, repeat coolant fill
procedure Step 1–6.
Caution
If the pressure cap is not tightly
installed, coolant loss and engine
damage may occur. Be sure the cap
is properly and tightly secured.
Automatic Coolant Service Fill
Instructions (2.0L Engine Only)
If equipped, this feature assists in
filling and removing air from the
cooling system after service of
components or when coolant is added
after being too low. To activate the fill and air removal
process:1. With a cold system, disconnect the
vent line from the port near the
cap on the surge tank. Add coolant
to the indicated mark on the
surge tank.
2. Reconnect the vent line to the surge tank and replace the cap on
the surge tank.
3. Connect the vehicle to a battery charger.
