Isuzu NHR 4J Series, Workshop Manual

Page: 246 / 406

ENGINE COOLING 6B - 3
Engine coolant change procedure
1.
To change engine coolant, make sure that the engine is
cool.
WARNING:
When the coolant is heated to a high temperature, be
sure not to loosen or remove the radiator cap.
Otherwise you might get scalded by hot vapor or
boiling water. To open the radiator cap, put a piece of
thick cloth on the cap and loosen the cap slowly to
reduce the pressure when the coolant has become
cooler.
2.
Open radiator cap and drain the cooling system by
loosening the drain valve on the radiator and on the
cylinder body.
NOTE:
For best result it is suggested that the engine cooling
system be flushed at least once a year. It is advisable
to flush the interior of the cooling system including the
radiator before using anti-freeze (ethylene-glycol
based).
Replace damaged rubber hoses as the engine anti-
freeze coolant is liable to leak out even minor cracks.
Isuzu recommends to use Isuzu genuine anti-freeze
(ethylene-glycol based) or equivalent, for the cooling
system and not add any inhibitors or additives.
CAUTION:
A failure to correctly fill the engine cooling system in
changing or topping up coolant may sometimes cause
the coolant to overflow from the filler neck even before
the engine and radiator are completely full.
If the engine runs under this condition, shortage of
coolant may possibly result in engine overheating. To
avoid such trouble, the following precautions should
be taken in filling the system.
3.
To refill engine coolant, pour coolant up to filler neck using
a filling hose which is smaller in outside diameter of the
filler neck.
Otherwise air between the filler neck and the filling hose
will block entry, preventing the system from completely
filling up.
4.
Keep a filling rate of 9 liter/min. or less. Filling over this
maximum rate may force air inside the engine and radiator.
And also, the coolant overflow will increase, making it
difficult to determine, whether or not the system is
completely full.
5.
After filling the system to the full, pull out the filling hose
and check to see if air trapped in the system is dislodged
and the coolant level goes down. Should the coolant level
go down, repeat topping-up until there is no more drop in
the coolant level.
6.
After directly filling the radiator, fill the reservoir to the
maximum level.