Installation manual

ManualsBrandsWesterbeke ManualsAutomotive11A-1

COOLING

SYSTEM

RAW

WATER

COOLING

SYSTEM

The

engine

is

designed

for

direct

raw

water

cooling.

The

engine

operates

with

a

raw

water

coolant

temperature

up

to

90"

F

(32°

C).

The

raw

water

flow

is

created

by

a

positive

displacement

impeller

pump

that

is

gear-driven

by

the

camshaft.

This

pump

draws

cooling

water

directly

from

the

raw

water

source

(ocean.

lake

or

river)

through

a

hose.

The

raw

water

is

pumped

through

a

tee

which

splits

the

flow.

The

tee

directs

some

of

the

flow

to

passages

in

the

engine

block

and

the

remainder

to

a

bypass.

The

flow

to

the

engine

block

circulates

around

the

cylinder

and

through

the

cylinder

head,

cooling

the

engine.

The

flow

through

the

bypass

goes

directly

to

the

exhaust

manifold/elbow,

and

is

at

its

greatest

when

the

engine

is

warming

up

and

the

thermostat

is

not

yet

open.

Flow

though

the

bypass

also

occurs

after

the

thermostat

is

open.

The

raw

water

that

is

flowing

through

the

engine

block

then

flows

through

the

thermo-

stat

to

the

exhaust

manifold/elbow

where

it

mixes

with

and

cools

the

exhaust

gases.

This

mixture

of

exhaust

gas

and

raw

water

is

discharged

overboard

by

the

engine's

exhaust

gas

discharge

pres-

sure.

The

coolant

temperature

switch

is

located

on

the

cylinder

head

for

Model

7 A-I,

and

on

the

thermostat

housing

for

ModelllA-1.

THERMOSTAT

A

thermostat,

located

on

top

of

the

cylinder

head,

controls

the

raw

water

coolant

temperature

as

the

coolant

flows

through

the

cool-

ing

system.

The

thermostat

is

set

to

the

maximum

temperature

of

140°

F

(60°

C).

When

the

engine

is

first

started,

the

closed

ther-

mostat

prevents

coolant

from

flowing

(some

coolant

is

by-passed

through

a

bypass

tube

to

prevent

the

exhaust

manifold

from

over-

heating).

As

the

engine

warms

up,

the

thermostat

gradually

opens.

The

thermostat

is

accessible

and

can

be

checked,

cleaned,

or

replaced

easily.

Carry

a

spare

thermostat

and

gasket.

Checking/Replacing

the

Thermostat

Remove

the

two

cap

screws

and

the

thermostat

housing,

then

remove

the

thermostat

from

the

cylinder

head

(see

illustration).

To

check

the

thermostat,

immerse

it

in

water

that

is

approximately

140°

F

(60°

C).

The

thermostat's

cone

must

then

be

fully

open-

this

indicates

the

thermostat

is

in

good

condition.

Use

a

new

gasket

when

reinstalling

the

thermostat

or

replacing

it.

Apply

a

thin

coat

of

sealant

on

both

sides

of

the

gasket

before

pressing

it

into

place.

Do

not

over-tighten

the

cap

screws.

Run

the

engine

and

check

for

normal

temperatures

and

that

there

are

no

leaks

at

the

thermostat

housing.

COOLANT

TEMPERATURE

SWITCH

The

coolant

temperature

switch

is

located

near

the

thermostat

housing

(see

illustration).

If

the

coolant's

operating

temperature

reaches

approximately

175°

F

(80°

C)

this

switch

will

activate

the

alarm

on

the

control

panel.

MODEL

lA·1

MODEL

11A·1

BLEED

HOLE

Engines & Generators

21

THERMOSTAT

HOUSING

CYliNDER

HEAD

THERMOSTAT

ASSEMBLY

Model

7

A·1

sIIown