Installation and Maintenance Manual form 185
Page 13
5.0 PERFORMANCE ISSUES
Determining the cause of overheating can be dicult. Here
are some things to look for:
WIRE REINFORCED RUBBER HOSE:
Could the rubber hose connecting the engine piping and the
cooler be collapsed? This could cut the cooling water supply
to the unit and reduce its eciency. Be sure you are using
wire reinforced rubber hose.
PIPING:
Is the piping between the engine and the cooler as large or
larger than the engine and cooler connections? (See section
2.5.4 under plumbing.) The piping should also be self-venting
and arranged so that a minimum number of elbows are used.
JACKETWATER:
Is the coolant circulating through the cooler? It may be taking
a path of least resistance through the bypass (if one exists).
THERMOSTAT:
Could the thermostat be stuck, or could the wrong thermostat
be in use? If so, it could give you a faulty temperature.
CIRCULATING PUMP:
Is the circulating pump working properly? If not, it could
reduce the cooling systems eciency.
AIR IN THE SYSTEM:
Was the unit installed in a way to allow all the air in the system
to escape? When a multiple-pass unit is mounted on the rake
of the vessel, make sure that the nozzles are mounted in the
up or high position. See sections 1.6.3, 2.5.6, 2.5.7, & 2.6.3
under Installation. See Figure 8
FOREIGN MATTER:
Could anything have gotten into the cooler nozzles? Make
sure that the orange plastic cap plugs covering the ends
of the hose connectors were removed and that no foreign
matter, such as a rag, was dropped into the cooler nozzles.
EXPANSION TANK:
Could the water level be too low in the expansion tank? This
can reduce the cooling system’s eciency.
EXTERNAL COATING:
Is the cooler painted or covered with any other coating? This
will have an insulating eect and will greatly reduce the heat
transfer rate of the unit. The standard recommendation is to
not coat the keel cooler.
WATER AERATION:
Could the water around the cooler be aerated in any way?
Aeration will reduce the heat transfer rate of the keel cooler.
MOORED AT DOCK:
Is the engine temperature rising while the vessel is moored
in dock? If the unit is installed near the propeller, engage
the propeller to circulate water past the unit, after taking the
proper safety precautions.
PLACEMENT:
Is an aftercooler circuit overheating? Make sure that the low
temperature cooling circuit is mounted forward of or closer
to the skeg or keel than the jacketwater coolers.
MOUNTING GASKETS:
Were the mounting gaskets put in place when the unit was
installed? The mounting gaskets supplied with the cooler
must be used to provide adequate spacing between the unit
and the ship’s hull. This will allow water to flow freely over
the cooler tubes.
GLYCOL:
How much glycol (antifreeze) is in the system? Perhaps the
cooler was not sized for the use of glycol in the system.
NOTE: Always premix glycol with water before adding
it to the cooling system.
NOTE: Never mix ethylene and propolyene glycol.
CRUSHED TUBES:
Have the rectangular tubes on the cooler been crushed or
pinched? This could restrict the internal water flow.
BLOWN TUBES:
Could the rectangular tubes on the unit have been blown or
bulged by unusually high pressures? If so, the exterior water
flow past the unit tubes could be impaired, retarding heat
transfer.
MARINE GROWTH:
Has your vessel been in dock for several months? You may
find marine growth on the unit which will hinder the unit’s
heat transfer rate. See Maintenance Section.
OIL DEPOSITS:
Have you had engine problems? Oil may have gotten into the
cooling water system and collected in the cooler, coating it
with an oil film. See Maintenance Section.
MINERAL DEPOSITS:
Could you be using hard water in the system? Mineral
Deposits can collect on the tube in the cooler, lining the
inside with lime, calcium, etc. See Maintenance Section.
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