Perkins 4GM - How to Check the Specific Gravity of the Coolant

Chapter 4 TPD1327E
Page 20
How to check the specic gravity of the
coolant
For mixtures which contain inhibited ethylene glycol:
1. Ensure that the machine is on level ground.
2. Operate the engine until it is warm enough to
open the thermostat. Continue to run the engine
until the coolant has circulated the cooling
system.
3. Stop the engine.
4. Allow the engine to cool until the temperature of
the coolant is below 140 °F (60 °C).
Warning! Do not drain the coolant while the engine
is still hot and the system is under pressure because
dangerous hot coolant can be discharged.
5. Remove the ller cap of the cooling system.
6. Drain some coolant from the cooling system into
a suitable container.
7. Use a special coolant hydrometer that will check
the temperature and the specic gravity of the
coolant, follow the manufacturer’s instructions.
Note: If a special coolant hydrometer is not
available, put a hydrometer and a separate
thermometer into the antifreeze mixture and check
the readings on both instruments. Compare the
readings with the chart (A).
8. Adjust the strength of the mixture as necessary.
If it is necessary to ll or replenish the coolant
system in service, mix the coolant to the correct
strength before it is added to the coolant system.
Protection against frost is as follows:
Antifreeze/water
(% by volume)
Protection
down to (°C)
50/50 -35
60/40 -40
Specic gravity chart
A = Percentage antifreeze by volume
B = Mixture temperature in Fahrenheit
C = Specic gravity
D = Mixture temperature in Celsius