Flushing The Cooling System; Radiator Service - Daewoo G424 Gasoline Service Manual

Filling
1. Check the radiator drain cock to be sure it is closed.
2. Check the engine drain plug to be sure it is tight.
3. Premix the antifreeze with clear water in 50/50
mixture.
IMPORTANT: If the old coolant is to be re-used, check
it for glycol/water mix of 50/50.
4. Place a large top funnel in the radiator fill hole.
5. Slowly pour in the coolant. The filling may be
slowed because of the thermostat being closed.
6. After the cooling system is filled to 1/2 inch below
the fill hole, start the engine and let the cooling
system warm up. When the thermostat opens, the
coolant level may drop. If the level drops, add
coolant until the level is up to the fill hole.
7. Replace the radiator cap.
8. Check the coolant level in the recovery tank.
Add coolant if needed.

Flushing the Cooling System

Various methods and equipment can be used to flush
the cooling system. If special equipment such as a
back flusher is used,
manufacturer's instructions.
NOTICE
If the engine is damaged Internally and a new engine
assembly is installed in the vehicle, make sure all
foreign material is completely flushed out of the
cooling system. The oil cooler system should also be
flushed out (if equipped). Failure to rid the oil or
cooling system of debris can result in damage to the
replacement engine.
IMPORTANT: Remove the thermostat before flushing
the cooling system.
G424 Service Manual
follow the equipment

Radiator Service

Radiator Internal Deposits
A radiator with a dirty, obstructed, or leaking core will
cause the engine to overheat. A scale deposit inside
the radiator is a result of using hard, high mineral
content water in the cooling system. The effect of heat
on the minerals in the water causes the formation of
scale, or hard coating, on metal surfaces within the
radiator, thereby reducing the transfer of heat. Some
hard water will produce a silt-like deposit which
restricts the flow of water. Replace a radiator that is
plugged or has a heavy scale on the core.
Scale Removal
To remove the hardened scale, a direct chemical
action is necessary. A flushing compound at the
specified rate of 30 grams per liter (4 oz. per gallon) of
radiator capacity should be added to the coolant
solution in the form of a dissolved solution while the
engine is running. Operate the engine for 15 minutes
or until it reaches normal operating temper-ature, then
drain and flush the system with clean water.
There are various types of flushing compounds
commercially available, but they should be obtained
from a reliable source. Most compounds attack metals
and should not remain in the engine for more than a
few minutes. A neutralizer should be used in the
cooling system immediately after a descaling solvent
is used. For extremely hard, stubborn coatings, such
as lime scale, use a stronger solution. The corrosive
action of a stronger solution will affect the thin metals
of the radiator, thereby reducing its operating life. A
complete flushing and rinsing is mandatory and must
be accomplished skillfully.
After the solvent and neutralizer have been used and
the cooling system is flushed, drain the entire system
and fill it with clean, soft water plus a high boiling type
antifreeze that meets GM 6038-M spec-ifications. After
filling the cooling system, check for radiator, hose, and
engine coolant leaks.
118 Cooling System