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COOLING SYSTEM - GENERAL
NOTE: Be sure to close the sea-cock
before working on the engine cooling system.
CAUTION: The cooling water in the engine
reaches extremely high temperatures. You must
use extreme caution when working on hot
engines to avoid burns. Allow the engine to cool
before working on the cooling system. Open the
filler cap carefully, using protective clothing
when the engine is warm.
WATER QUALITY
1. Distilled, deionized, soft water is preferred for use in
cooling systems. Bottled distilled water from a food
store or water supplier is recommended. Tap water
often has a high mineral content. Tap water should
NEVER be put in a cooling system unless first tested
by a water quality laboratory. Do not use water
made by the reverse osmosis method unless it has
been PH neutralized.
2. Here are acceptable water quality specifications:
Contaminates
Maximum Chlorides
Maximum Sulfates
Maximum Dissolved Solids
Maximum Total Hardness
3. If chlorides, sulfates or total dissolved solids are
higher than the above given specification, the water
must be distilled, demineralized, or
deionized before it is used in a cooling system.
4. If total hardness is higher than 170 ppm and all other
parameters are within the given
specifications, the water must be softened before it is
used to make coolant solution.
Updated 11-8-13
Servicing
Parts
Grains
per Million
per Gallon
40
2.5
100
5.9
340
20.0
170
10.0
PH Level 5.5 to 9.0
OM843NW3 5/19
SP-13. CHECK THE COOLANT LEVEL
1. Check the coolant level each day before starting the
engine. Check the water level by removing the
pressure cap from the expansion tank.
In order to give the cooling water an opportunity to
expand, the level should be about 1 in. (2.5 cm) below
the filler cap sealing surface when the engine is cold.
2. The pressure valve in the filler cap releases when the
pressure is approximately 7 PSI (0.5 bar). Use a cap
pressure tester to check cap if you suspect it is faulty.
SP-14. COOLING SYSTEM FLUSHING
1. Flush the cooling system every 2500 hours or every
12 months, whichever comes first.
2. Marine sets:
a. Remove expansion tank cap and drain engine
block.
b. Open block drain cock. Remove hose from
bottom of heat exchanger tank.
c. Pour clean water into expansion tank until water
coming from drains is free of discoloration and
sediment. Let water drain completely. Close
drains and refill with recommended mixture.
3. Coolant Specifications:
Use 50% distilled water / 50% ethylene glycol anti-
freeze mix. Antifreeze mixture is recommended as a
good year-round coolant.
4. Check hoses and connections and repair any leakage.
SP-15. HEAT EXCHANGER
1. Clean the heat exchanger core once a year or after
2500 hours of operation.
2. Drain expansion tank and heat exchanger.
3. Remove heat exchanger end covers and remove
core.
4. Clean the inside of exchanger core tubes using
a metal rod. Flush, inspect and clean again if
necessary.
5. Reassemble. Fill the cooling system, start the engine
and check for leaks.
22
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