engine cooling system basics - steve ferguson

7/31/2019 Engine Cooling System Basics - Steve Ferguson

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BySteveFerguson

GMCWS Technical VP


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Componentsconsist

of:

1.Source

of

heat.

3.Water

pump. ermos a

5.Fan6. Expansiontank


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Ratherthanbuildse arate

radiatorsfor

each

source

of

heat,

t e ra ator asprov s ons

oilcooler.

Both

of

these

depend

oncoolantintheradiatorto

temperatures.


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Withoutsomemeansoflimitingtheflowofcoolantto

dissipateheat

from

these

sources,

they

would

never

be

abletogetuptooperationaltemperatures.

Thisis

where

the

thermostat

comes

into

play.

It

thereservoir/radiator. Aproperlyworkingthermostat

willopen

at

aspecific

temperature

and

regulate

flow

oncethesourceregainsthedesignoperating

temperature.

GMCsoriginallyhad195degreethermostatsinstalled

.


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WaterPum s


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isit

critical

that

the

impeller

have

an

anti

impeller.

Eachof

the

pumps

pictured

will

work

well.

Thenewwaterpumpshaveasmall,

stam edsteel

im eller

and

the

also

work

well.


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RadiatorCaps

Makesurethatwhicheverconfigurationyouchoose,itisrated

atnomorethan9lbs. Yourradiatorma beratedhi herthan

thatbut

your

unless

youve

replaced

your

heater

core,

it

is

also

ratedat9lbs.


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Theradiatorca hasafivefold ob:

. ,

2.Closure

cap

to

keep

coolant

in

the

radiator,

3.Pressurecaptopreventoverheatingbypressurizingthe

systemtoraisetheboilingtemperatureofcoolantandallow

theautomobile'senginetooperateatmoreefficienthigher

tem eratures

4.Pressurereliefvalvetosafelyandharmlesslyventexcess

pressureintotheoverflowjug,and

.

overflowjugbackintotheradiatortopreventairfromentering

thesystemandallowingthecoolanttoperformitsfunction

moreefficiently.


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expansiontanks


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s ecoo an ea sup, expan s. nce

reachesacertainpressureintheradiator,the

tension

spring

in

the

cap

and

allows

the

excess

coolantunderpressuretooverflowintothe

expansiontank,orrecoverytank.

ent ecoo anttemperature nt era ator

drops,thevolumeofthecoolantcontractscreating

radiatorfromtheexpansiontankthusmaintaining

acom letel filledradiator.


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, .

substitutes.

The

fan

is

coupled

to

the

water

pump

with

a

thermostaticallycontrolledclutch.

Itisnotnecessaryforthefantooperateat100%ofthe

enginerpm

at

all

times.

If

it

did,

the

engine

would

most

likelyneverreachproperoperatingtemperatureandthe

parasiticlossonpowerwouldsignificantlylowerMPG.

Enterthefanclutch


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yourcoolantAfterinitialfillup,andtheradiatorisfullandthe

capis

installed,

all

level

checking

should

be

done

at

.

throughitsheatingandcoolingcycles,coolant

neededto

replace

air

trapped

in

the

block

will

be

drawnfromtheexpansiontank. Thisiswhereyou

addcoolant. Removingtheradiatorcapwillresultin

lossof

s stem

balance

and

it

will

take

another

heating/coolingcycletoreestablishthisbalance.


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Whichoneisri ht?


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P/N154644forthe455engine

Andthe403engine

The

light

duty

AC

Delco

part

number

that

cross

references

to

the

OEM

fan

clutch

is:

P/N154223forthe455and

e

eng ne


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replacements.

Hayden,Murray,

NAPA,

.

Manyof

these

are

made

by

the

same

companyan aremar ete un er erent

brands.

Also,AC

Delco

outsources

some

of

itsfanclutchesandHaydenisoneofthe

sources.

Tor ueFlo

Autozone

fan

clutchesaremadebyHaydenandtheHD

.


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,

differencesbetween

different

models

and

a so erences e ween esamemo e s

withdifferent

manufactures.

First,thetestsetup!


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es ngwas

one

us ng

ap o o

ac ome er

totestfanspeedwiththefanclutch

, .


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disengaged,each

one

was

run

for

10

minutes

with

no

heata liedtothebimetalliccontrols rin s. U on

initialinstallationonthetestfixture,allclutchfans

werefullyengagedfromstorage.

Dynamic

testingconsisted

of

using

aphoto

tachometertorecordthespeedofthefanbladeand

themotordrivenpulleywiththefanclutchfully

sengage .

en

ea e

eme a c

con ro

springtofullyengagethefanclutchandagain

.


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FanClutchTestResults

Alltestin wasdoneusin a1h electricmotordrivin awater um witha7blade

3"pitch

5.5

fan.

ACDelco154644 #1

Enginerpm Fanrpm Enginerpm Fanrpm

1,292

1,000

1,268

1.238

ACDelco154644 #2

1,289

1,030

1,259

1,227

ACDelco154949

1,320 357 1,255 1,226

Hayden9727


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s

you

can

see

rom

e

num ers,

e

keyelementinperformanceisthe

percentageofrpmthatthefanspinsin

relationtoen iner m. Inthecaseof

theonesItested,theACDelcomodels

percentageofenginerpmwhile

clutches.


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Tempprobe


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Witha195RobertShawbalancedflowthermostatinstalled, aluminum

radiator,Curtisfullfanshroud,ambientairtempsinthelow80s,ItooktheGMCforatestdrive(withtheACon)todetermineatwhatairtemps(insidethe

, , .

Fanengages

Coolanttemp: 215deg Shroudairtemp:198deg

Coolanttemp: 200deg Shroudairtemp: 176

The154644clutchfanrespondsquicklytotheriseinshroudairtempswhen

thethermostatfullyopens. Typically,thecoolanttempplungeswhenthefan

engagesbutittakesafewmilesat65mphfortheclutchfanhousingtocool

enoughfor

the

clutch

to

fully

disengage.


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Inadditiontobenchtesting,ItestedallthelistedfanclutchesinmyGMC

.

range,some

stop

and

go,

and

sustained

speeds

of

65

mph.

_____________________________________

Insummary,ifyouliveinarelativelycoolclimate,youmaywanttoruntheHayden

. .

Whenengaged,itspinsatthesamepercentageofenginerpmastheheavydutyAC

Delcounits. ThisreducedparasiticdragcouldresultinalittlemoreMPG.

Inthe

hot

SW,

the

HD

AC

Delco

units

are

the

only

way

to

go.

Ifyouhaveanaluminumradiatorinstalled,themostefficientthermostatisthe190

degRobertShawbalancedflowunit. MrGasketperformancethermostatsarenot

recommended as the tend to o en sooner and close later resultin in constant fanclutchcycling. Thealuminumradiator,coupledwiththeACDelcoHD4644fan

clutch, theRSbalancedflowthermostat isthebestcombinationItested. This

combinationresultedinverystablecoolanttemperaturesandminimumclutchfan

cyc ng.

engine cooling system basics - steve ferguson

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