Perkins 415GM - Engines Fitted with Keel Coolers; How to Check the Specific Gravity of the Coolant

N39453 Chapter 4
Page 73
Engines tted with keel coolers
The coolant capacity and the method used to drain the coolant circuit of an engine connected to a keel cooler
will vary in different applications.
Use the instructions given by the keel cooler manufacturer to drain and renew the engine coolant when a keel
cooler is tted.
How to check the specic gravity of the coolant
For mixtures which contain inhibited ethylene glycol:
1. 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.
2. Stop the engine.
3. Allow the engine to cool until the temperature of the coolant is below 140
O
F (60
O
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.
4. Remove the ller cap of the cooling system.
5. Drain some coolant from the cooling system into a suitable container.
6. 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 (H).
Specic gravity chart
A = Percentage antifreeze by volume
B = Mixture temperature in Fahrenheit
C = Specic gravity
D = Mixture temperature in Celsius
7. Adjust the strength of the mixture as necessary.
Note: If it is necessary to ll or replenish the cooling system in service, mix the coolant to the correct strength
before it is added to the cooling system.
Caution: An antifreeze to water ratio of 50:50 should be used even in warm ambient temperatures, in order to
maintain the concentration of the corrosion inhibitor in the antifreeze.