Westerbeke 12.0KW - 50Hz EDT Installation Manual download pdf (Page 21)

COOLING

SYSTEM

DESCRIPTION

Westerbeke

marine

diesel

engines are designed and equipped

for

fresh

water

cooling.

Heat

produced in

the

engine

by

com-

bustion

and

friction

is

transferred

to

fresh water coolant

which

circulates throughout the engine.

'This

circulating fresh

water

coolant

cools

the

engine block, its internal moving

parts,

and

the

engine

oil.

The heat

is

transferred externally

from

the

fresh

water

coolant to raw water

by

means of a heat

exchanger,

similar

in

function to

an

automotive

radiator.

Raw

water

flows

through the

tubes

of the heat exchanger while

fresh

water coolant

flows

around

the

tubes; engine heat trans-

ferred

to

the

fresh

water coolant is conducted through

the

tube

walls

to

the

raw

water

which is then pumped into the

exhaust system

where

finally

it

is

discharged overboard.

In

other

words,

the engine

is

cooled by fresh water coolant,

this

coolant

is

cooled

by

raw

water,

and the raw water carries the

transferred heat overboard

through the exhaust

systeJ]l.

The

fresh

water

coolant and

raw

water circuits

are

independent

of

each

other.

Using

only

fresh

water

coolant

within

the

engine

allows

the

cooling water passages

to

stay clean and free

from

harmful

deposits.

FRESH

WATER

COOLING

CIRCUIT

NOTE:

Refer

to

the

ENGINE

COOLANT

section

for

the

rec-

ommended

antifreeze

and

water mixture

to

be

used

as the

fresh

water

coolant.

Fresh

water

coolant

is

pumped through the engine

by

a circu-

lating

pump,

absorbing heat from the engine. The coolant

then

passes

through

the

thermostat into the manifold,

to

the

heat

exchanger

where

it

is

cooled, and returned

to

the engine

block

via

the

suction side of the circulating

pump.

ENGIKE

BLOCK

COOLAKT

DRAIK

When

the

engine

is

started

cold,

external coolant

flow

is

pre-

vented

by

the

closed thermostat (although

some

coolant

flow

is

bypassed around

the

thermostat

to

prevent

the

exhaust

manifold

from

overheating).

As

the

engine

warms

up,

the

thermostat gradually opens, allowing

full

flow

of

the

engine's

coolant

to

flow

unrestricted

to

the

external portion of

the

cooling

system.

Coolant

Recovery

Tank

A coolant recovery tank

allows

for

engine coolant

expansion

and

contraction during engine operation, without

any

signifi-

cant loss

of

coolant

and

without introducing air into

the

cool-

ing system.

'This

tank should

be

located at or

above

the

engine manifold level and should

be

easily

accessible.

CHANGING

THE

ANTIFREEZE

COOLANT

The engine's antifreeze coolant must

be

changed according

to

the

MAINTENANCE

SCHEDULE.

If

the

coolant

is

allowed

to

become

contaminated

or

loose

its

protection

ability,

overheating issues

can

result

as

well

as

external

cylinder erosion and can cause the raw water pump shaft

seals

to

leak:.

A

WARNING:

B~re

tIf

the~hot

engine

coo/ant.

Wear

protective

gloves.

Drain the engine antifreeze coolant by removing the block

drain plug

and

opening

the

drain petcock plug

on

the

lower

side

of

the

heat exchanger along with removal of

the

pressure

cap

on

the water jacketed exhaust manifold. Flush

the

system

with

fresh clean

water,

then

start

the

refill process.

A

CAUTION:

Proper

cooling

system

maintenance

is

critical;

a,

substantial

number

of

engine

failures

can

be

traced

back

to

cooling

system

corrosion.

Engines & Generators

14

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