SECTION CONTENTS

Marine Cooling System

Contents / Notes Page

Marine Cooling System Functions ...................................................................................................................................................................... AG-09_5 - 2

Marine Cooling System Types............................................................................................................................................................................ AG-09_5 - 2

Engine Coolant Flow........................................................................................................................................................................................... AG-09_5 - 3

Radiator Cooling........................................................................................................................................................................................ AG-09_5 - 3

Heat Exchanger System............................................................................................................................................................................ AG-09_5 - 3

Sea Water Aftercooled Engines ................................................................................................................................................................ AG-09_5 - 6

Keel Cooling .............................................................................................................................................................................................. AG-09_5 - 7

Single Circuit Keel Cooling of Engines ............................................................................................................................................... AG-09_5 - 7

Dual Circuit Keel Cooling of Engines ................................................................................................................................................ AG-09_5 - 10

Engine Coolant ....................................................................................................................................................................................... AG-09_5 - 16

Cabin Heaters.......................................................................................................................................................................................... AG-09_5 - 16

Radiators ................................................................................................................................................................................................. AG-09_5 - 16

Direct Cooling .......................................................................................................................................................................................... AG-09_5 - 16

General Practices .................................................................................................................................................................................... AG-09_5 - 16

Appendix A: Definitions..................................................................................................................................................................................... AG-09_5 - 17

Appendix B: Instructions for John Deere Marine Calculator - Keel Cooler Sizing ............................................................................................AG-09_5 - 17

History of Changes ........................................................................................................................................................................................... AG-09_5 - 20

Engine Application Guidelines AG-09_5 March 2017

 MARINE COOLING SYSTEM

MARINE COOLING SYSTEM FUNCTIONS Radiator Cooled

For radiator cooling, please see Application Guidelines, Cooling System
Marine cooling systems have six main functions: (AG-09).
Heat Exchanger Cooled
1. Cool the engine.
Heat exchanger cooled engines (designated in the engine model name by
The cooling system must carry waste heat away from the engine. The “AFM”), use a water-to-water heat exchanger that brings sea water to an
waste heat is then transferred to sea water or in some cases, the am- engine-mounted heat exchanger to cool the engine coolant. Sea water is
bient air. This can be done with a heat exchanger, keel cooler, box pumped into the vessel and through the heat exchanger before being ex-
cooler, or even a radiator. pelled overboard.
2. Maintain proper engine operating temperature. Sea Water Aftercooled
To identify the appropriate operating temperature, please reference A variation of a heat exchanger cooling system is a sea water aftercooled
the appropriate Performance Curve specifications . Some engines re- system (designated in the engine model name by “SFM”). In this system,
quire cooler intake air temperatures in order to meet the US EPA and in addition to the engine heat exchanger, the engine also has a sea water
EU emission requirements.. aftercooler (to cool the intake air). Sea water is first pumped through the
3. Deaerate the coolant. aftercooler, and then through the heat exchanger, before it is expelled
Deaeration is the process that removes air from the coolant and iso- overboard
lates it to prevent air recirculation through the cooling system. Failure Keel Cooled
to deaerate can result in cavitation, which can reduce coolant flow, and “Keel cooled” is used generically throughout this document to refer to Box
cause engine overheating and liner pitting. Cooler, Keel Cooler, etc. Each of these systems share some features but
4. Allow for coolant expansion. are also quite different.
The cooling system must provide space for coolant expansion without In keel cooled engines, a water-to-water heat exchanger made up of a sys-
overflowing as the coolant warms up. Typically the expansion space tem of pipes or channels, mounted to the external surfaces of the vessel's
must be about 7% of the total coolant volume in the system. hull, is used to cool the engine coolant. Keel cooling pumps the engine
5. Provide for coolant fill. coolant through the hull, to the keel cooler, and back to the engine.
There must be a way to fill the system with coolant at the initial fill and In dual circuit keel cooled engines, an engineered water-to-water keel
to maintain the proper coolant level in the system after the initial start- cooler is used to cool the intake air and a fabricated or engineered water-
up. to-water keel cooler is used to cool the engine coolant. Both are mounted
to the external surfaces of the vessel's hull. The engine coolant pump
6. Maintain cooling system pressure. moves the engine coolant through the engine and hull to a keel cooler and
The pressure cap maintains pressure in the system to prevent the back to the engine. The sea water pump/auxiliary pump moves coolant
coolant from boiling or from evaporating. The cap also maintains the through the aftercooler and the hull to a second keel cooler and back
coolant cleanliness by preventing contamination. again.

Regardless of the type of cooling system used, all marine engines are
MARINE COOLING SYSTEM TYPES equipped with a coolant water pump, thermostat, and pressure cap. Heat
exchanger cooled engines also have a sea water pump, heat exchanger,
The main types of marine cooling systems are: and in the case of sea water aftercooled engines, a sea water after cooler.
• Radiator cooled In addition, electronic engines have sensors that monitor the coolant tem-
perature. In order to protect the engine, when configured in trimable op-
• Heat exchanger cooled tions, the ECU will derate engine power if the high temperature limit of the
• Sea water aftercooled coolant is exceeded.
• Keel cooled.
This document will address each type of system in detail except radiator
cooled.

Engine Application Guidelines AG-09_5 - 2 March 2017

 MARINE COOLING SYSTEM

ENGINE COOLANT FLOW • The outlet line exits the engine, routing coolant from the thermostats
to the keel cooler or heat exchanger.
As shown in the diagram below, regardless of the type of cooling system • Heat is transferred from the coolant in the heat exchanger or keel cool-
chosen, the basic coolant flow through the engine is the same. er and rejected to sea water.
• The return line is the external line returning coolant to its original
source. For keel cooled engines it is the line returning coolant from the
keel cooler to the engine top tank. For heat exchanger cooled engines
it is the engine coolant line exiting the heat exchanger.
• The bypass and return flows are combined in the expansion tank por-
tion of the top tank. Keel cooled engines require an external expan-
sion tank connected to the top tank above the engine to provide area
for coolant expansion and to maintain proper coolant pressure.

Radiator Cooling
Please see Application Guidelines, Cooling System (AG-09).

Heat Exchanger System

Heat exchanger cooling is the most common cooling system on marine en-
gines. These engines have a complete, self contained cooling system.
The internal heat exchanger provides the heat transfer from the engine
coolant to the sea water. Zinc anodes are installed in the sea water side
of the heat exchanger to protect the parts in contact with sea water from
electrolysis.
Engine Coolant Flow
The system works by pumping sea water through the bottom of the hull
and one or two strainers by the sea water pump. Sea water strainers are
• The engine water pump draws coolant from the heat exchanger or keel required to keep foreign materials from reaching the sea water pump. It is
cooler. The top tank is a coolant tank provided on marine engines for a good practice to use two strainers, a coarse outboard strainer (scoop) at-
expansion and deaeration. The coolant is pumped through the block tached to the hull and an inboard fine strainer to further remove debris from
and exhaust manifold to the thermostats. the sea water before it goes to the sea water pump.
• The inlet line is the supply line to the engine coolant pump.
• The thermostats split the coolant flow between the outlet line and the After passing through the strainers and the pump, the sea water flows
bypass line. The split changes to control the coolant temperature be- through the heat exchanger cooling the engine coolant. In the heat ex-
tween 160-180° F. changer, the cool sea water flows through the tubes in the heat exchanger
• The bypass line allows the coolant to bypass the heat exchanger or and the hot engine coolant flows around the outside of the tubes.
keel cooler returning uncooled coolant to the engine. This line is inter-
nal on John Deere marine engines.
Once through the heat exchanger, the sea water is discharged overboard,
usually through a wet exhaust elbow.

Engine Application Guidelines AG-09_5 - 3 March 2017

 MARINE COOLING SYSTEM

HEAT EXCHANGER FLOW DIGAGRAMS PLUMBING CONSIDERATIONS

The diagram below shows the flow of coolant through the engine and ma- The following items should be considered when plumbing a heat ex-
rine components. Blue lines show coolant, green lines indicate sea water changed engine:
flow and purple indicates air flow. • A sea cock is needed to shut off sea water during maintenance. The
valve should be installed as close as possible to the location where the
sea water enters the hull.
• Inlet line and components in the line must keep the restriction to the
Sea Water sea water pump less than 8.8 inches of Mercury, 4.3 psi, or 30 kPa.
Sea Water AFM Sea Water Cooling
Strainer Pump Warning: Do not use a Mercury manometer on an aluminum boat.
Mercury penetrates the aluminum oxide protective outer
P coating on aluminum and will perforate an aluminum plate
Heat Exchanger in a matter of hours. For the same reason, Mercury is not
permitted to be carried or shipped on commercial aircraft.
JW Pump • Sea water exiting the heat exchanger can either be plumbed directly
overboard or through a gear oil cooler and/or wet exhaust elbow and
P
Expansion
then overboard. Pressure at the outlet of the sea water pump must not
De-aeration exceed the limit specified in the corresponding Performance Curve.
Tank 1 Engine Also, when plumbed overboard the line should be above the waterline
Port
Turbo to minimize restriction and to prevent sea water from being drawn into
the engine when the engine cools down.
• Gear oil coolers should be installed in the sea water return line to avoid
the added inlet restriction. The temperature rise of the sea water leav-
ing the engine is typically less than 27° F (15 °C) and is more than ad-
Aftercooler equate for a gear cooler.

Heat Exchanger System Flow

Heat Exchangers are typically found on recreational vessels, vessels that

operate in deep water with little debris, high speed vessels where weight
is a concern and on large ocean-going vessels.

Engine Application Guidelines AG-09_5 - 4 June 2016

 MARINE COOLING SYSTEM

HEAT EXCHANGER PLUMBING DIAGRAMS ADVANTAGES AND DISADVANTAGES OF

HEAT EXCHANGER-CONTROLLED ENGINES
The following diagrams show how the engines should be plumbed for a
heat exchanged system. Advantages:
A heat exchanger cooled engine is a simpler installation. The only pip-
ing required is the sea water inlet and return; the rest is provided with
the engine. The expansion tank is integral with the engine, an auxiliary
expansion tank and/or overflow bottle is not required. Also, it requires
a smaller volume of coolant as compared to a keel cooled engine.
Disadvantages:
A heat exchanged system offers several disadvantages.
• Sea water pump impellers are wear items and must be replaced
on a regular basis.
• In cold environments, ice may clog the sea strainers causing the
engine to overheat.
4045 and 6068 Plumbing (Heat Exchanger) • When operating in salt or corrosive water, the heat exchanger tube
bundle, sea water pump, sea water piping and valves must be
checked periodically for corrosion, and will eventually require re-
placement.
• Zinc anodes in the heat exchanger(s) must be serviced every 250
hours.

INSTALLATION OF HEAT-EXCHANGED ENGINES

When installing a heat-exchanged engine, keep the following in mind:

• To help protect the sea water impeller from damage, install two
sea strainers to filter out debris. Use a sea scoop on the outside
of the hull and a sea filter inside the hull, before the pump.
6081 Plumbing (Heat Exchanger) • To isolate vibration, use flexible connectors between the sea water
inlet lines and the sea water pump.
• If needed, install the gear oil cooler in the sea water return line.
• Completely purge (or “bleed”) the engine cooling system of air af-
ter the initial coolant fill.
• Follow the engine coolant guidelines discussed at the end of this
guideline.

6125 Plumbing (Heat Exchanger)

Engine Application Guidelines AG-09_5 - 5 January 2016
 MARINE COOLING SYSTEM

SERVICING HEAT-EXCHANGED ENGINES

Heat-exchanged engines require some regular maintenance. This main-

tenance is specified in the Operator’s Manual and includes: Sea Water Sea Water AFM Sea Water Cooling
Strainer Pump
• Maintain coolant for maximum system and engine life.
• After draining the coolant from the engine, always purge/bleed air P
from the system. Heat Exchanger
• If sudden, hot running conditions arise, check for damage to the
sea water impeller. JW Pump

• Inspect zinc anodes for deterioration. If the anode length is less P

than 1.25 in. (31.75 mm), or the outer diameter is less than 0.219 Expansion
in. (5.55 mm), replace the anodes. Tank 1 De-aeration Engine
Port
Turbo
Sea Water Aftercooled Engines

Sea water aftercooled engines are a special type of heat exchanged en-
gines. Sea water is first routed through a sea water aftercooler to cool the
intake air before it is sent to the heat exchanger. The cooler intake air re- Aftercooler
sults in higher power and lower exhaust emissions.

SEA WATER AFTERCOOLER FLOW DIAGRAMS AFM Sea Water Cooling

The following diagram shows the cooling system flow for a sea water after-
cooled engine. Blue lines show coolant, green lines indicate sea water flow
and purple indicates air flow. SFM Sea Water Cooling
Heat Exchanger

Sea Water JW Pump

Filters TFM Sea Water Cooling
Pump

P P
Expansion
Heat Exchanger De-aeration
Tank 1 Engine
Port
JW Pump Turbo

P
Expansion
De-aeration Engine
Tank 1
Port
Turbo P Aftercooler

Sea Water Sea Water

Strainer
Pump

TFM Sea Water Cooling SFM Sea Water Cooling

Engine Application Guidelines AG-09_5 - 6 January 2016
 MARINE COOLING SYSTEM

PLUMBING CONSIDERATIONS Keel Cooling

A sea water aftercooled engine is plumbed the same way as a heat ex-
changer cooled engine. The same considerations listed above still apply. SINGLE CIRCUIT KEEL COOLING

Keel cooling uses water-to-water heat transfer through a keel cooler sys-
ADVANTAGES AND DISADVANTAGES OF tem attached or welded to the outside of the vessel's hull. Keel coolers
SEA WATER AFTERCOLLED ENGINES may be fabricated from "C" channel, round pipe (or half-round pipe), or
they may be a manufactured unit such as a "Gridcooler™" or box cooler.
Sea water aftercooled engines have the same advantages as the heat ex- Engines that are keel cooled do not use sea water pumps for engine cool-
changer cooled engines, with the addition of higher power as a result of the ing however sea water pumps may be used on a keel cooled engine for
cooler intake air temperatures. auxiliary service such as deck wash-down or bait tank circulation.

The same disadvantages listed for heat exchanged engines still apply to The size of the keel cooler varies based on these factors:
this engine. In addition, in many cases, sea water aftercooled engines • The power rating and heat rejection rate of the engine
cannot be keel cooled and maintain the same power levels. Keel cooling
this engine would require separate keel coolers for the aftercooler and the • The engine coolant flow rate
heat exchanger. (See "Dual Circuit Keel Cooling of SFM Engines.") Also, • Water temperature in which the vessel operates
there are more zinc anodes on this engine, for both the aftercooler and the • Whether the keel cooler is painted or bare metal. Bottom paint is
heat exchanger. a great thermal insulator but is essential corrosion protection for
the vessel hull. Aluminum (or even copper) hulls that do not re-
INSTALLATION AND SERVICING OF quire bottom paint can have much more efficient heat transfer
SEA WATER AFTERCOLLED ENGINES from the keel cooler, and therefore, use a smaller keel cooler than
would otherwise be required.
Because this is a variation of the heat exchanged engine, the same instal- • Vessel's normal operating speed
lation and service requirements apply. As mentioned under the disadvan- • The keel cooler's shape; channel or pipe.
tages section, these engines have additional zinc anodes that need to be
inspected and replaced as necessary.
Appendix B has instructions for utilizing the John Deere Marine Calculator
for keel cooler sizing of non-engineered keel coolers.

Engine Application Guidelines AG-09_5 - 7 January 2016

 MARINE COOLING SYSTEM

Keel Cooler Flow Diagrams Plumbing Considerations for Single Circuit

In a keel cooled system, engine coolant is used to carry heat away from Coolant expansion occurs as the coolant warms up from engine operation.
the engine. Hot engine coolant flows from the thermostat outlet to the keel As the coolant expands it needs somewhere to go. Coolant typically ex-
cooler. Heat is transferred from the coolant through the keel cooler to the pands 5% in volume from "cold" to "hot" so the minimum coolant expansion
sea water. In a properly designed keel cooler, the temperature difference tank size is about 7% of the total system volume.
between the keel cooler inlet and outlet should be a minimum of 12°F; 7° C.
The tank should be sized for the total cooling system volume expansion
plus added volume for de-aeration space, and the unusable volume within
The diagrams below show the coolant flow in a keel cooler applications. the tank. (Since the expansion tank should never be completely empty
Blue indicates cool coolant while purple indicates air flow. when the engine is running, the bottom couple of inches (centimeters) of
the expansion tank is considered "unusable volume.") The total system
volume includes the volume within the engine, plus the volume of the keel
cooler and connecting piping, but not the expansion tank. The minimum
Circuit 1 Keel expansion tank volume can be calculated with the following formula:

JW Pump
Minimum Expansion Total Coolant Vol. Engine Coolant Vol.
Tank Volume = +
P
18 4.5
Expansion
Tank 1 De-aeration Engine
Port John Deere engine-mounted expansion tanks have some extra expansion
Turbo space in the top tank but an auxiliary tank is usually required with keel cool-
ers because of the large overall coolant volume in a keel cooling system.
When plumbing an auxiliary expansion tank, keep in mind that it must be
TFM Single Circuit Keel Cooling the highest point in the cooling system. This helps ensure proper deaera-
tion of the system. Air caught in the system because of poor deaeration
can cause a variety of problems including liner and water pump cavitation,
TFM Single Circuit Keel Cooling corrosion of the engine water passages, loss of coolant as the air expands,
and engine overheating. All John Deere marine engines require a pres-
sure cap. Please reference the appropriate Performance Curve specifica-
AFM Single Circuit Keel Cooling tion for the Minimum Pressure Cap requirement. It is never acceptable to
run the engine without a pressure cap. Deere accessories are available to
Circuit 1 Keel replace the pressure cap with an adaptor to add an auxiliary expansion
tank.
JW Pump
Additional items that should be considered when installing a keel cooler:
P
Expansion
• If a single fill/vent line between the expansion tank and the engine can-
De-aeration Engine
not be used, separate lines must be used to fill and vent the tank. A
Tank 1
Port ¼" vent line is routed from the engine top tank to the expansion tank.
Turbo The expansion tank fill line goes from the bottom of the expansion tank
to the top of the engine-mounted expansion tank or the keel cooler re-
turn line. When a gear oil cooler is used, the coolant make-up connec-
tion should be between the gear oil cooler and engine coolant inlet.
• The water lines should be large enough to handle the coolant flow.
Aftercooler
Minimize the number of bends and elbows to keep the inlet restriction
as low as possible. The lines should be routed so air will naturally flow
out of them and below the connection points on the engine. If this is
AFM Single Circuit Keel Cooling not possible, to eliminate trapped air, additional vent lines will be nec-
essary at all high spots in the piping.
Engine Application Guidelines AG-09_5 - 8 January 2016
 MARINE COOLING SYSTEM

Keel Cooler Plumbing Diagrams

The following pictures show how to properly plumb a keel-cooled system.

6081 Plumbing (Keel Cooler)

4045 and 6068 Plumbing (Keel Cooler)

6125 Plumbing (Keel Cooler)

Engine Application Guidelines AG-09_5 - 9 January 2016

 MARINE COOLING SYSTEM

DUAL CIRCUIT KEEL COOLING OF SFM ENGINES Dual Circuit Keel Cooling Flow Diagrams

Dual circuit keel cooling (DCKC) uses water-to-water heat transfer through A DCKC cooled system works the same as a single circuit system except
a keel cooler system attached to the outside of the vessel's hull. Engines has the added complexity of two keel cooler circuits; one for the engine and
with dual circuit keel coolers use the engines coolant pump to circulate en- one for the aftercooler. In a properly designed keel cooler the temperature
gine coolant through circuit 1 which cools the engine, exhaust manifold, difference between the keel cooler inlet and outlet should be a minimum of
and turbo. The sea water pump/auxiliary pump circulates coolant through 12° F or 7° C.
the circuit 2 which cools the intake air only. John Deere requires dual cir-
cuit keel cooling of SFM engines to use an engineered keel cooler for cir- The diagram below shows the coolant flow in a keel cooler application.
cuit 2. The size of the keel cooler varies based on the following: Blue lines show coolant, green indicates sea water flow and purple indi-
cates air flow.
• The power rating and heat rejection rate of the engine.
• The engine coolant flow rate.
• Temperature of the water the vessel is operating in. SFM Dual Circuit Keel Cooling
• Whether the keel cooler is painted or bare metal.
Bottom paint is a great thermal insulator but is essential corrosion Circuit 1 Keel
protection for the vessel hull. Aluminum (or even copper) hulls that
do not require bottom paint can have much more efficient heat JW Pump
transfer from the keel cooler, and therefore, use a smaller keel
cooler than would otherwise be required. P
Expansion
• The vessel's normal operating speed. De-aeration
Tank 1 Engine
• The keel cooler's shape. Port
Turbo
Due to the complexity of dual circuit systems, only engineered coolers are Expansion
allowed for circuit 2. De-aeration
Tank 2
Port

P Aftercooler

Pump

Circuit 2 Engineered Keel

SFM Dual Circuit Keel Cooling

Engine Application Guidelines AG-09_5 - 10 January 2016

 MARINE COOLING SYSTEM

Plumbing Considerations for Circuit 1 (Heat Exchanger) Target the rated manifold air temperature (MAT) specified in the Engine
Performance Curve (Engine Installation Criteria) found on the Power Sys-
Same as "Plumbing Considerations For Single Circuit" keel cooling. tems Portal. This temperature generally ranges from 104o F - 122o F
(40o C - 50o C) for M5 ratings and incrementally drops for each consecu-
tive rating below M5. During a sea trial, when operating steady state at rat-
Plumbing Considerations for Circuit 2 (Aftercooler) ed speed it is important to verify aftercooler temperature margin via the
following equation:
Warning:
An improperly designed keel cooler circuit for the aftercooler can lead TCurrent MAT + Y (TStandard Sea Water - TCurrent Sea Water) < TTarget MAT
to multiple failure modes, such as:
• Poor performance or even engine damage and/or failure due to Where: Y ~ 1, and TStandard Sea Water = 27 oC
excessive intake air temperatures
• Failed aftercooler core leading to coolant ingestion and potential When designing the system, it is also important to account for the maxi-
hydro locking of engine. mum Sea Water temperature in which the vessel will operate, and to verify
• Inability to meet emissions requirements. that the Maximum Manifold Air Temperature (MMAT) will not be violated.
A simple calculation with the same assumptions as the previous equation
An expansion tank of adequate volume must be designed and added to the can be used;
aftercooler circuit. This tank, when properly sized and located, will serve
several purposes. It will act as a reservoir and expansion tank, help de- Simply substitute TStandard Sea Water with TMax Sea Water , and
aerate the circuit, and help stabilize the sea water pump inlet pressure. TTarget MAT with TMMAT.
• For tank sizing see Plumbing Considerations for in Keel Cooling
• The tank circuit must be located just in front of the Sea Water / Note: MAT temps as indicated by the ECU reading. This temp is subject
Auxiliary pump inlet and T-connected into the pump supply line / to sensor placement so it is imperative the data comes from the
keel cooler return line. same location.
• 3/4” fill as a minimum; Keel cooler supplier analysis will dictate the maximum Sea Water temper-
• 1” to 1-1/4” fill is recommended ature this type of system can be designed for to achieve aftercooler tem-
• The tank elevation must be above the aftercooler and keel cooler perature targets specified in the Engine Performance Curve. Generally,
to allow de-aeration of the system. this type of system is limited to locations where Sea Water temperatures
do not exceed 22o C.
• Keel cooler and other plumbing must keep the restriction to the
Sea Water pump inlet less than 8.8 inches of Mercury, 4.3 psi, or [As a generalization, to achieve a cost effective package, a 5-10o C
30 kPa. delta between target temp and cooling media is required. Also the
EPA stipulates emissions compliance up to 27o C Sea Water Temper-
Warning: atures.]
Do not use a Mercury manometer on an aluminum boat. Mercury In a properly designed keel cooler, the temperature difference between the
penetrates the aluminum oxide protective outer coating on alumi- keel cooler inlet and outlet should be a minimum of 12o F (7o C).
num and will perforate an aluminum plate in a matter of hours. For
the same reason, Mercury is not permitted to be carried or shipped The Sea Water pump impeller is rubber and therefore needs to be consid-
on commercial aircraft. ered a service item.
It is recommended that the Heat Exchanger and Aftercooler use separate
expansion tanks in order to:
• Prevent hot and cool fluid mixture from the vent port flow.
• Maintain adequate system pressure on the engines rigid impeller
pump.
• Allow the use of non-coolant mixtures in the Aftercooler circuit.

Engine Application Guidelines AG-09_5 - 11 June 2016

 MARINE COOLING SYSTEM

Dual Circuit Keel Cooler Plumbing Diagrams

The following figures show how to properly plumb dual circuit keel cooled systems. Connection points are shown in red.
Note 1 - If an auxiliary expansion tank is required, connect it to this location. Fill/Vent line should have a minimum 1-1/4" inside diameter, slope not less
than 30 degrees. For more information, see Plumbing Consideration.
Note 2 - Gear oil coolers must be plumbed to the engine return side of the engine cooling circuit. Gear oil cooler should not be plumbed into the aftercooler
cooling circuit.

Available vent ports

To Keel for Keel Cooler 1
Cooler 1 Note 1
Available vent ports
for Keel Cooler 2

Return from To Keel Cooler 2

Keel Cooler 1 Outlet design
not complete

Return from
Keel Cooler 2

4045SFM Dual Keel Cooling

Available vent ports

for Keel Cooler 1 Vent for Keel Cooler 2 Note 1
pending updates.

Return from
To Keel To Keel Keel Cooler 2
Cooler 1 Cooler 2

Return from
Keel Cooler 1

6068SFM Dual Keel Cooling

Engine Application Guidelines AG-09_5 - 12 June 2016

 MARINE COOLING SYSTEM

Available vent port

for Keel Cooler 1 Available vent port
Note 1 for Keel Cooler 2
To Keel
Cooler 1

Return from
Keel Cooler 1

To Keel
Cooler 2

Return from
Keel Cooler 2

6090SFM Dual Keel Cooling

Available vent port

Note 1 for Keel Cooler 2

Available vent ports

for Keel Cooler 1

To Keel
Cooler 1
To Keel
Cooler 2

Return from
Keel Cooler 1

Return from
Keel Cooler 2

6135SFM Dual Keel Cooling

Engine Application Guidelines AG-09_5 - 13 June 2016

 MARINE COOLING SYSTEM

Types of Keel Coolers An alternative to fabricating a keel cooler onsite is to purchase a keel cool-
er from a keel cooler manufacturer. These units are installed on the side
As mentioned above, keel coolers come in various shapes and styles. of the vessel, often in a recessed area that is used to protect the unit from
Channel style coolers can be made of structural or ship and car channel. damage.
The channel is welded to the hull of the boat and forms a passage for the
coolant to flow through.

Manufactured / Engineered Keel Cooler

Channel Keel Cooler

Several companies that make keel coolers:

Duramax® Marine LLC

Round or half-round channel may also be used to fabricate keel coolers. 17990 Great Lakes Parkway
Hiram, OH 44234
Phone: 440-834-5400
www.duramaxmarine.com

R.W. Fernstrum & Company

1716 11th Avenue
PO Box 97
Menominee, MI 49858
Phone: 906-863-5553
www.fernstrum.com

The Walter Machine Company, Inc

84-98 Cambridge Avenue
Jersey City, NJ 07307
Half-round Pipe Keel Cooler Phone: 201-656-5654
www.waltergear.com

Engine Application Guidelines AG-09_5 - 14 January 2016

 MARINE COOLING SYSTEM

Advantages and Disadvantages to Keel Cooling Installation of Keel Coolers

Keel coolers are commonly found in North America and occasionally in When installing keel coolers, keep the following thoughts in mind :
other locations. They are becoming more common outside of the U.S., es- • Keel coolers must be clean. Before filling with coolant and connecting
pecially on oil exploration vessels because the designs originated in the the engine, make sure that any dirt, debris, sand, rust and welding slag
U.S. Gulf Coast where keel cooling is commonly used. has been removed.
Because keel coolers do not plug or clog with flotsam, jetsam, or ice, they • To isolate vibration, use flexible connectors such as hose or flexible
are frequently used on North American commercial boats working in shal- pipe between engine and keel cooler piping.
low and silty water. They are also used in areas such as Alaska, Maine,
and Scandinavia because of ice, jelly fish, and sea grass. The robust de- • Install a vent line from the engine top tank and keel cooling piping to
sign of keel coolers requires minimumal maintenance. the expansion tank if needed.
• Provide the shipyard with the required expansion tank size, and make
sure they know where to connect the expansion tank piping to the en-
Keel coolers are easily fabricated by the boat builder and can be used on gine.
steel or aluminum hulls. Keel coolers are seldom used on fiberglass or
wooden hulls, recreational vessels, or large ocean-going vessels. • If necessary, install the gear oil cooler in the keel cooler return line.
• At the initial fill, completely purge (“bleed”) the system of air.
Because of the weight of a fabricated keel cooler, plus the extra coolant
volume, fabricated keel coolers add to the boat displacement. Keel cool- Servicing Keel Coolers
ers also increase the external drag, especially on high speed vessels. Re-
pairs can be costly and require the boat to be pulled out of the water. Keel Keel coolers require some regular maintenance to help ensure proper
coolers may become plugged internally with sediment, sludge or slime, cooling.
and the lack of a drain makes them very difficult to clean. Keel coolers
need protection from external damage caused by floating debris, or con- • For maximum system and engine life, maintain proper coolant mix.
tact with other vessels, docks or grounding. • After draining coolant from the engine or keel cooler, always purge
("bleed") air from system.
Keel Cooler Sizing • Sudden hot running conditions may be attributed to damage to exter-
nal keel coolers and can subsequently cause overheating damage to
the engine.
For non-engineered keel coolers, please see Appendix B for directions to
use the John Deere Keel Cooler Sizing program. This program can be
used to size channel, round, or half-round fabricated keel coolers.

Engine Application Guidelines AG-09_5 - 15 January 2016

 MARINE COOLING SYSTEM

Engine Coolant from over-heating and/or to keep the engine from running cold when the
engine is in use), heater supply lines should be no more than 1" ID (25 mm
ID). Engine installation drawings call out the locations where cabin heaters
Engines and keel coolers should be filled with coolant that meets John and water heaters may be plumbed to, and from, on the engine.
Deere requirements. For the latest coolant recommendations, please ref-
erence the appropriate Operator Manual. When selecting coolant, keep
these thoughts in mind: Radiators
• Coolant should be used in all areas, even those that do not have freez-
ing weather. Plain water with additives is not acceptable. When necessary, Marine engines may use radiator cooling. Typically radi-
ators are necessary when the engine is required to run when the vessel is
• If not premixed with the antifreeze, the coolant must have a Deere-ap- out of the water, or when the engine is deck mounted. If the engine is in-
proved water treatment additive. stalled below-deck, the radiator is mounted on-deck and the cooling fan is
• Many marine "water treatments" do not meet John Deere standards for driven by a hydraulic or electric motor.
coolant. Some are not formulated for high-speed diesel engines.
• Do not use automotive antifreeze with silicon additives. When plumbing the engine to a radiator, keel cooler connection points
• Always make-up coolant with a proper coolant mix. Never use plain should be used. Installation recommendations can be found in the Indus-
water to make-up lost coolant. trial Engine Cooling System of the Application Guidelines.

Selecting coolant can be very confusing. We recommend using John Direct Cooling
Deere Cool-Gard coolant. This coolant includes the Deere water treat-
ment additive and has been formulated to work with high-speed diesel en- In a direct cooling system, sea water is pumped directly through the engine
gines. Cool-Gard is available as a concentrate or a ready-to-use high in place of coolant. This is NEVER acceptable for John Deere marine en-
performance glycol based anti-freeze fluid. It minimizes the formation of gines. Silt deposits and corrosion resulting from this type of operation can
deposits, prevents foaming and offers protection from -32°F to +230°F (- accumulate in the engine and cause extensive damage.
36°C to +110°C ). It also includes a wetting agent that improves contact
between the product and the surfaces to be protected (cylinder block, lin-
ers, water pump, oil cooler, and many others). If John Deere coolant is not General Practices
used, to make sure the correct coolant is used, read the Operator Manual
and coolant labels carefully.
When using any type of cooling system, some good practices to follow are:

Coolants of different origins and types should not be mixed. The perfor- • All engine piping connections to the vessel must be flexible enough to
mance of coolant may be negatively affected when mixed with other allow for relative movement between the engine and the vessel piping.
brands of engine coolants. John Deere TY16175 Coolant Test Kit may be Acceptable connections are reinforced rubber hose and/or flexible bel-
used to check the coolant quality. lows.
• Hose length should be kept to a minimum.
• Hose routings must be kept clear of hot locations on the engine and
Cabin Heaters exhaust system. They must not touch or rub against fixed structures.
To prevent over-heating of hoses from radiated heat, use heat shields.
A cabin heater or domestic water heater can be used with John Deere ma- • The cooling inlet and outlet connections should be the same size or
rine engines. The heater system must allow air to vent from the system. larger than the connections on the engine.
Heaters located above the engine require an auxiliary expansion tank.
Even heaters mounted below the engine may require vent lines to the en- • Select hoses compatible with glycol coolant and with maximum tem-
gine expansion tank. Engine heat, especially during warm-up and at light perature ratings of 230°F (110°C) or higher.
load operation, may not be adequate to provide heat for the cabin heater
or water heater. To limit coolant flow to the heater (to prevent the engine

Engine Application Guidelines AG-09_5 - 16 January 2016

 MARINE COOLING SYSTEM

APPENDIX A: DEFINITIONS APPENDIX B: INSTRUCTIONS FOR JOHN DEERE

MARINE CALCULATOR -
Box cooler - a series of round tubes in a "U" shape, similar to a keel cooler, KEEL COOLER SIZING
but installed in a protected location such as a sea chest.
Coolant - the cooling fluid that circulates through the engine and heat ex- John Deere has developed a calculator to help size the keel cooler re-
changer, keel cooler or radiator. quired for each of our engine ratings. This calculator is only for on-site fab-
ECU - Engine Control Unit - the electronic controller or "black box" that ricated keel coolers, not for manufactured coolers. The calculator uses
controls the engine. The ECU software can be programmed to provide Ship and Car channel with planned improvements to include structural
different engine responses to fault conditions, throttle input locations, channel sizes. Ship and Car channel was originally designed for riveted
governor settings, idle speeds, and other controls. construction and has parallel flange sides so that rivets could be installed
"square" on both sides. Ship and Car channel is typically used for ship
Flotsam and jetsam - any debris floating in sea water. Traditionally flotsam construction. Structural channel has draft on the inside of the channel
and jetsam describe ship's cargo that has been thrown into the ocean. flanges. It is typically used in welded construction where parallel sides are
There is a technical difference between the two: jetsam has been vol- not necessary.
untarily cast into the sea (jettisoned) by the crew of a ship in order to
lighten it in case of an emergency; while flotsam describes goods that
are floating on the water without having been thrown in deliberately, of- The following step-by-step instructions go through a sample calculation.
ten after a shipwreck or washed overboard in a storm.
Grid Cooler - the brand name for keel coolers manufactured by the RW
Fernstrum Company. Grid Coolers use square channel shapes or
"grids" instead of round tubing. For added protection from damage,
Grid Coolers are sometimes installed in a recess in the hull.
Keel - the bottom structural member of a boat and usually the first part that
is laid down when construction begins. The "laying of the keel" marks
the beginning of construction.
Keel cooler - originally, piping attached to the vessel's keel to provide en-
gine cooling. Now used to denote a cooling system that is attached
anywhere on the outside of the hull.
Sea chest - a box framed into the hull that provides a protected connection
for sea water inlets or box coolers.
Sea water - it's what floats your boat. Sea water is the term used for any
untreated water used for engine cooling whether it is salt water, fresh
water, lake, river, or pond water.

Engine Application Guidelines AG-09_5 - 17 January 2016

 MARINE COOLING SYSTEM

Engine Tab Boat Tab

Step 2, On the "Boat" Tab: Input the minimum vessel speed. For gensets,
Step 1, On the "Engine" Tab: From the pull down menu, select an engine use "0" knots and for propulsion engines in towing applications, "4" knots.
model and rating. This will automatically populate the heat rejection, cool- For all other applications use the vessel speed when fully loaded.
ant pump flow, coolant volume and thermostat temperature fields.
Step 3, On the "Boat" Tab: Select the keel cooler material. Aluminum and
copper coolers must not be painted. As mentioned in the keel cooler sec-
tion, paint is a very good thermal insulator and will increase the keel cooler
size.

Step 4, On the "Boat" Tab: If it is a propulsion engine with a gear oil cooler,
under "Marine Gear Oil Cooler," select "Yes." For engines without a gear
oil cooler, select "No."

Step 5, On the "Boat" Tab: Enter the maximum sea water temperature in
which the vessel will operate. For most applications, 90°F should be used.
Use a lower temperature only if the vessel will operate exclusively in cold
water areas such as Alaska, Canada, or Scandinavia.

Step 6
On the "Boat" Tab: Enter the number of parallel flow paths. If the water is
in one continuous path with no "splits," enter "1." Otherwise, enter the
number of different flow paths the coolant can take through the keel cooler.
Engine Application Guidelines AG-09_5 - 18 January 2016
 MARINE COOLING SYSTEM

Step 7
On the "Keelcooler" Tab: The results are given for channel, round, and
half-round pipe keel coolers. The results calculated are the "best" size giv-
en the information provided.

Select desired size

from pull-down
menu.

Required keel
cooler area

Boat Tab

The required keel cooler area is also listed for use in manual keel cooler
size calculations of unusual shapes and sizes.
Keelcooler Tab
Step 8
In some cases the boat builder uses sizes other than the recommended
size, or a different shape. On the "Print/Units" tab: You may print out the results of the keel cooler
program from this page, or from the "File" menu at the top of the screen.
You may also switch between English and Metric units on this page, or
If the boat builder uses Ship and Car channel, round, or half-round pipe, from the "Units" tab at the top of the page.
from the drop down menus, select the size being used. Once entered, to
see the new required length and expansion tank size, click on the "keel-
cooler" Tab. In some cases it may say "Flow is too slow." That means that
the size of channel or pipe being used it too large for the amount of flow
and there may be problems with overheating.

Engine Application Guidelines AG-09_5 - 19 January 2016

 MARINE COOLING SYSTEM

HISTORY OF CHANGES

Date Section Owner EIB Page(s) Description of Change(s)

2016Jan15 Michael Van Donsel All pages Revised text and artwork; Addition of Dual Circuit Keel Cooling
2016Jun7 Michael Van Donsel page 11 Added recommended tank circuit line sizes and maximum sea water temperature
guidance for Dual Circuit Keel Cooling (DCKC).
2017 Mar9 Michael Van Donsel page 1, 2, 3 References added for radiator cooling.

Engine Application Guidelines AG-09_5 - 20 History of Changes