Isuzu 4BG1 Instruction Manual page 49

corrected. If you do not find a leak or other problem, carefully
add engine coolant to the reserve tank. (Engine coolant is a
mixture of ethylene glycol antifreeze and water. See "Engine
Care in cold season" in Section 6 for the proper antifreeze and
mixture.)
.
If the engine coolant level in the reserve tank is at the correct
level but there is still an indication on the instrument panel of
an overheat condition:
l
YOU MUST LET ENGINE COOL FIRST. You may then add
engine coolant directly to the radiator.
Once the Engine Coolant Temperature Gage no longer signals
an overheat condition, you can resume operating at a reduced
speed. Return to normal operating after about ten minutes if
the gage pointer does not again show an overheat condition.
If no cause for the overheat condition was found, see a qualified
service technician.
Overcooling
The engine operation at low coolant temperature will not only
increase the oil and fuel consumption but also will lead to
premature parts wear which may result in engine failure.
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