Ford Cooling System Seminar By: Andy Wiedeman Member of the Rocky Mountain A’s As Presented at the Cooling Seminar Feb. 25, 2012 In Franktown, Colorado
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Ford
Cooling System SeminarBy: Andy Wiedeman
Member of the Rocky Mountain A’sAs Presented at the Cooling Seminar
Feb. 25, 2012In Franktown, Colorado
Ford
A Short History of Coolingthe Model A Engine
As horsepower increased water cooling was introducedusing a water pump to force coolant through the engine
Manufacturers wanted simpler means for cooling
Designers wanted a non-pumped cooling system toavoid failed pumps … The pumpless Thermo-Syphon systen evolved … A debate ensued pump or “no pump”
Henry Ford adopted the thermo-syphon for the “T”
Most manufacturers continued to use the water pump
The Model A modified the “T” system to use BOTH !
Ford
The Thermo-Syphon Coolingof the Basic Model A System
The Model A engine cooling system evolved from theearlier Model T Thermo-Syphon design
Cool Water Entering
Hot Water AscendingThe Radiator
cools the watercausing it to
become denserand “sink” to
the bottom of theof the radiator
Top of theEngine iswell below theRadiator inlet
All Passagesmust besmooth withno obstructions
The 1930-1931 Model A’s have a raised radiator inletto get additional Thermo-Syphon cooling action.
Ford
So what’s with theModel A Water Pump?
The engineers of the Model A added a water pump the early 5 impeller pumps gave way in 1930 to a 3impeller design (Replacement pumps are 3 impeller blades for all years)
The Model A waterpump must hot water from theengine … But notobstruct the flow
“suck”
Most Manufacturers ofthe time put the waterpump here to use gravityto feed the pump and the water through the engineat a higher rate of flow than the Model A
”push”
The pump is used at highengine speeds to increasethe water flow andmaintain a more eventemperature.
Basic cooling is stillthe Thermo-Syphonsystem
Ford
Pump Aided Thermo SyphonCooling
The Engine cooling is at atmospheric pressurethe water pump aids coolant flow at high speeds
AtmosphericPressure
High Pressure PumpOutput
Low PressureThermo SyphonCooling
Ford
How do the variousDesigns Compare ?
EarlyAutos
Model T Model A ModernAutos
Comments
CoolingDesign
CoolantFlow
Pressurized
FlowRegulated
DesignCoolant
PumpForcedWater
Up to100 galper min
Varies withheating0 to 25Gpm
36 to 38Gpm
100 Plusgal per min
ThermoSyphon
No Pump
ThermoSyphon
Pump aided
PumpForced
Coolants
NO NO NO
YESUsually to
1 Atmosphere(15 psi)
YES NO NOYESwith
Thermostat
DistilledWATER
DistilledWATER
DistilledWATER
AntifreezeMixtures
with Additives
The Model A ismostly a ThermoSyphon System(Last to Use it)
The Model Apump “sucks”water from theengine
Thermostats raiseengine temp fastin winter for moreefficiency
Typical “hot”Operating
Temperature
Typically190
deg F
Varies150 to 200
deg F
195 to 220 deg F
PressurizationIncreases themargin to boilingby raising the BP
The Model A hasmuch less marginfor boiling at highaltitudes
Modern cars aredesigned for usingthe less efficientAntifreeze coolant
Boiling
Ford
What is Actually beingCooled ?
The principle elements that are being cooled are thecylinder wall oil lubricant and the valve seat area.
Cool Cylinder WallTemperatureslower than theOil Flash Pointof ~ 380 deg F
Keep Valve Guidesbelow Lubricantfailure.
Cool Hot Spots in theHead near the Valves
There must be a “Balance” between cylinder wall tempand engine efficiency … thus the designers set theCylinder Wall Temp as high as possible to get themost out of the engine & keep the coolant from boiling
Ford
Energy Balance in theModel A Engine
Hot Coolant to Radiator
About 35% of
Fuel Combustion Energy
Exhaust Gasses
to Atmosphere
About 35% of
Fuel Combustion
Energy
Combustion
Friction in System
to the Wheels
About 10%
POWER
About 20% of
Fuel Energy
Radiation
from the hot
Engine Parts
to the Atmosphere
(Very Small)
20% - 25% Power
10% Friction
35% Out theExhaust Pipe
35% Lost to CoolingWater
The Cooling System in the Model A must remove about 35% of the energy burned in each gallon ofgasoline consumed
The overall efficiencyof most gasoline enginesis about 20% to 25%
Combustion
POWER
About 20% of
Fuel Energy
Ford
Can the Engine be tooCool ?
“ The best temperature to secure efficient operation is one on whichconsiderable difference of opinion exists … It is very important thatthe engine not get too hot, and at the same time is equally as vitalthat the cylinder should not be robbed of too much heat ” Victor Page - 1931
writing about the Model A
Engine Wear Fuel ConsumptionHorsepower
140 150 160 180
0.0010
0.0003
130
29.5
28.5
3.2
2.8
Inch
es o
f C
yl W
ear
Hors
e P
ow
er
Gallon
s/H
ou
r
Tests Performed in 1950’s - 60 hours of continuous operation by ContinentalMotors as shown in Stockel’s Automechanics Fundamentals. Not a Model A Engine
Temperature deg F
En
gin
eSlu
dge
Cra
nk c
ase
Con
den
sati
on
190 140 150 160 180130 190 140 150 160 180130 190
Norm
al R
an
ge
Model A
Norm
al R
an
ge
Model A
Norm
al R
an
ge
Model A
Temperature deg F Temperature deg F
Ford
Heat Transfer at theCritical Cylinder Wall
Coolant
Flow
Cylinder
Wall
Cast
Iron
Scale/Rust& Corrosion(Undesired Insulator)
Oil Film to beProtected fromburning
Piston
Steam Absorptioninto the Bulk Coolantat lower temperature~ 160 to 190 deg F
Combustion
Coolant Vapor Filmandat the Cylinder Wall
Nucleate Boiling
Piston Comprssion Ring
Stagnant GasBoundary Layeron the innerCylinder Wall(Desired Insulator)
Combustion
Ford
What do we meanby Nucleate Boiling ?
SIDE B
Nucleate Boiling
Enhanced by
reducing the
Surface Tension
of the Coolant
reducing the
bubble size and
allowing more
New coolant to
contact the hot
metal
CoolantFLOW
Steam BubblesRecombining withCooler Fluid
Steam BubblesForm where theHot Metal Surfacemeets the incomingcoolant flow
The water jacket wallis controlled by thecoolant flow to about275 deg. F
Depending on the altitudeof operation steam bubblesform at the surface(212 deg F at Sea Level andabout 200 at Denver)
The steam bubbles carrythe heat away from thesurface thus cooling it
If the coolant temperatureand flow is sufficient toallow reabsorption of thesteam bubbles all is well
Exit Temperatureabout 180 deg F
Inlet TemperatureDepends on Radiator Conditionbut generally 20 deg less than Exit Temperature
Ford
Temperature Profileof the Model A Cylinder Wall
EXAMPLE Average TEMPERATURES - MODEL A FORD CYLINDER WALLAt Sea Level
2000
1200
350
212
160 - 180
Combustion Gas Temperature
Average Boundary LayerGas Temperature
Inner Cylinder Wall Oil FilmTemperature (desired)
Outer Cyl. Wall Temperature275Coolant Temperature at Wall
Bulk Coolant Temperature
Cylinder
Wall
Piston
TemperatureProfile
Degre
es F
Ford
Motor Oil Flash PointsVary with Producers
Design Margin can be as low as 40 deg F or as high as 157 deg FFor Average Oils is is about 80 deg F
At Sea Level (flash point testing by MicaPeak Labs 2005)
350
160 - 180Bulk Coolant Temperature Cylinder
Wall
Piston
TemperatureProfile
Average Motor Oil Flash Points 415 - 450 deg F
Typical Engine Design(Model A design point is Unknown)
oWorst - 392 FExxonSuper Flow
oBest - 507 FAmsoil
Ford
Conditions Leadingto Cooling Failure
Incorrect Spark Timingand Spark Advance
Incorrect Fuel toAir Mixture
Altitude &Temperatureof the DrivingConditions
Amount of Scale andCorrosion on the waterjacket walls
RadiatorConditionCapacity &Flow Rate
Type ofCoolant
Red Text are Conditions over which we have Control
Ford
Cooling Failure
Steam & SuperheatedCoolant Blocks Flow
Coolant Flow Drops toNearly Zero
Normal CoolantFlow
Nucleate BoilingSteam is reabsorbedinto the Coolant Stream
Surface Boilingoverwhelms theCoolant Stream
Large SteamBubbles Form
Minor failure - delayed trip up to ½ hour or more
Major failure - Blown head gasket, cracked blockWarped head, cracked radiatorBurned Pistons, scored cylinder walls
Ford Cooling Marginand Strategies
210
200
190
180
170
160
1502 4 6 8 10 120
Detr
oit
MI
Den
ver
CO
Eli
zabeth
CO
My H
ouse
Eis
en
how
er
Tun
nel
32 D
eg
14 D
eg
Altitude (ft x 1000))
About 50% of Margin Lostdue to Altitude
Strategies to Improve Margin
Typical Operating Temp
- Ensure Engine is Timed Correctly. Adjust Mixture
- Flush Radiator Often
- Ensure no obstructions in the water flow paths
- Use highest efficiency coolant
- Improve coolant efficiency
- Use a four core radiator for higher capacity
Lowered Average.Operating Temp
Ford
My Experience withImprovement of Radiator
210
200
190
180
170
160
150
3 Core Radiator(Average Condition)Depends on Air Temp
4 Core Radiator (New)
Alt
itude
Miles
Tem
perature R
ise
1 2 3 4 5 6 75000
6000
7000
8000
2nd Gear - 2250 RPM
High Gear - 1850 RPM
1 2 3 4 5 6 7
Miles
Sedalia to My Garage - 1610 ft in 7 miles
Engine exit temperature stabilizes at 190 deg F *
Measured over 75 times* With 4 core radiator
Sedalia 5840 ft
My Garage7450 ft
Entrance toJarre Canyon
Ford
BREAK
What Cooling Fluids to Use
Next
How to Improve on Water as a Coolant
Ford
COOLANTSWhat Choices Do We Have?
Plain Ol H O2
Modern Ethylene or Propaline Antifreeze Coolants
Water with an Additive to improve cooling
- Used since the beginning of the automobile industry
- In 1928 to 1931 was used to design the Model A cooling system
- Free or nearly so
- Ford recommended use only in Winter from 1930 on
- Modern Antifreeze Coolants introduced in 1950’s
- Modern Automobiles designed to use them year round from 1960’s
- The racing crowd wanted better cooling
- Redline Oil and others developed surface tension reducers
Ford
COOLANT Properties
SPECIFICHEAT
LATENTHEAT
BOILINGPOINT
SURFACETENSION
SCALECOMBAT
ABILITY TO ABSORB HEATAffects Reabsorption of SteamThe higher the value the better
ABILITY TO TRANSFER HEATAffects Extraction of Heat
The higher the value the better
TEMP at NUCLEATE BOILINGHigh BP means higher metal
temp - Lower is better
ABILITY TO MOVE STEAM BUBBLESLow values mean smaller steambubbles at the metal boundary
ABILITY TO STOP SCALE BUILDUPScale and corrosion of the water
jacket form an insulator
Importance
VERYHIGH
VERYHIGH
HIGH
Medium
Medium
SPECIFICHEAT
LATENTHEAT
BOILINGPOINT (1)
SURFACETENSION
SCALECOMBAT
Ford
COOLANT Performance
Distilled Water
Antifreeze 50/50with water
Distilled Waterwith a Surficant(WaterWetter)
1.00
0.80
1.00
540cal/gm
375cal/gm
540cal/gm
582dynes/cm
512dynes/cm
282
dynes/cm
(1) at Elizabeth CO(2) Surficant means Surface tension reducer
200deg F
213deg F
200deg F
NO
YES
YES
HIGHVALUEBEST
HIGHVALUEBEST
LOWVALUEBEST
LOWVALUEBEST
ReabsorbsSteam
Bubblesinto coolant
flow
ExtractsHeat from
the Cylinderwall by
vaporization
Point atwhich
nucleateboilingbegins
Lower valuemeans small
bubblesthat breakaway easier
Water isthe mostcorrosive
useDistilled to
reducescale
FREEZEPROTECT
NO
YES
NO
Only AntiFreeze willprotect in
Winter
Ford
COOLING PERFORMANCECoolant type Comparison
Distilled Water
50/50 Mixture Antifreeze
100%80%
Basis: Engineering Tests Coolants for system designswww.engineeringtoolbox.com(Notes that flow must be increased)
50/50 Mixture Antifreeze
228202
Distilled Water
220
H O + WaterWetter2
Degrees F at EngineExit to Radiator
Basis: Dynometer TestsMalcom Garrett Racing EnginesChev 350 Cast Iron BlockThermostat @ 160 deg FRun @ 7200 RPM for 3 hoursEngine Coolant Measured atend of each test run.
Note: Performance ina Model A Ford with anunpressurized coolingsystem is unknown
Ford
COOLANT TradeoffAntifreeze versus Plain Water
Modern Antifreeze Coolants have other benefits
Modern Antifreeze Coolants have less cooling capacity
- Year round use- Corrosion Protection- Higher Bulk Boiling Temperature in Colorado +12 deg F
- Higher Nucleate Boiling Temp REDUCES margin for Oil Flash Point- 20% Lower specific heat LOWERS the ability to reabsorb steam- 30% Lower latent heat LOWERS ability to extract heat from cyl wall
THE BOTTOM LINE - Plain Water is better
THE BOTTOM LINE - Antifreeze is better
Antifreeze has less cooling but a higher boiling point(washes out?) NOT really, the antifreeze will raise thecylinder wall temperature because of its high BP
Ford
What Water to Use
When using Water as a coolant or as a mixturewith Antifreeze be sure to (not justdeionized) water … Definitly tap water.
USE DISTILLEDNOT
Tap and Well water in the Colorado Front Rangeis high in Alkaline content, calcium, magnesium,iron, and flourides. Minerals deposit in the engine
Water at 190 deg F is 30 times more corrosive thanat 70 deg F causes scale buildup clog radiator
Add WaterWetter to combat corrosion
Ford
Why Do Modern AutoManufacturers MandateAntifreeze Coolants ?
Long Warranty Periods MANDATE corrosion protection
High use of Aluminum in engines for weight reductionrequires much more corrosion protection
Modern automobiles are designed to use the lowerperformance antifreeze coolants
- Forced circulation at 100 gallons/min plus by efficient water pumps
- Pressurized cooling system raises boiling point for high altitude
- Non Thermo-Syphon system design allows thermostat use
- Customer demand for less maintenance
Ford
Can we IMPROVE on Waterto get the Antifreeze Benefits ?
The answer is YES with some additional maintenance
Water ADDITIVES on the market offer better coolingand corrosion protection
- WATER WETTER by Red Line Oil- PURPLE ICE by Royal Purple Oil- ENGINE ICE
DisclaimerI have not researchedother products thanWater Wetter
These additives DO NOT provide winter antifreeze
Water Wetter DOES provide corrosion protection
Water Wetter DOES provide better heat transferthan plain old water and much better than antifreeze
- - SAVE the winter Antifreeze and use it for many years
REQUIRES two changes of coolants each year
Ford
How Does Water WetterWork ? How Good Is it ?
SIDE A Water or 50/50 Antifreeze SIDE B Water + Water Wetter
NucleateBoiling
Reduced SurfaceTension allowssmall steam bubblesto carry away heatfrom cylinder wallsmall steam bubblesare absorbed intocoolant flow easier
High SurfaceTension makeslarge steam bubblesthat can coalesce intoa vapor barrier raisingengine temperature
PERFORMANCE (Engine coolant temp at exit to radiator)
Red Line Claim “ Up to 20 degrees lower operating temperature”
Import Tuner Mag1993 Miata test
“10 deg in mixed driving - 13 deg sustained driving”
Anecdotal Tests Commenter’s averaged about 5 to 8 deg lower
MODEL A Tests TBD - to be conducted next summer
Ford
Cooling Margin Improvementwith Water Wetter
210
200
190
180
170
160
1502 4 6 8 10 120
Den
ver
CO
Eli
zabeth
CO
My H
ouse
Eis
en
how
er
Tun
nel
32 DegSea LevelMargin
18 D
eg
Altitude (ft x 1000))
Expected Improvement ~ 5 deg over Antifreeze
Minimum
- Based on Comments- Miata/Corvette tests- Anecdotal test reports
- Based on tests of my Model A with a 4 core
23 D
eg
33 D
eg
(Not Confirmed)
Typical Operating Tempat 6000 ft with Antifreeze
Expected with Water Wetter
Measured 4 CoreRadiator Temp
Could be much more
Ford
Why Not Add Water Wetterto Antifreeze ?
Red Line claims OK to add Water Wetter to Antifreeze (yields an overall performance about same as plain water)
… BUT
Internet Forums and some Car Clubs claim it causesa brown slime, gunk, and deposits in the engine
I contacted Red Line and here is their response- It is due to silicate dropout because users did not change their antifreeze regularly not a Water Wetter problem- It is due to oxidation from leaking head gaskets not Water Wetter - In a Model A you should use it with water not antifreeze
However they also said ...
Where there is smoke there is fire … I go along withthe Rolls Royce Club in the UK and DO NOT thinkit is a good idea to mix it with antifreeze.
Ford
BREAKNext
Radiator Performance
Thermostats - a help or a hindrance ?
Ford
HOW RADIATORS WORK
HOT WATER
IN
COOLER
WATER
OUT COOL AIR IN
HOT AIR OUT Radiating Fins
Cooling Tubes
The Model A Radiatoris a
“Compact Fin & TubeHeat Exchanger”
Heat Exchangeis by
fromthe Tube to the Finand from
the Fin to the Air Flow
Conduction
Radiation
Radiation From
Fin
Condu nc it Fion in
Water TempTin
Water TempTout
FIN
TubeRadiation
from Tube
Air Flow
Ford
The MODEL A RADIATOROpen to Air
SplashBaffle
Smooth Flowto Engine
Coolant Movesdown through the Radiator byGravity andthe Change inDensity of thewater due tocooling.
Average Changein Temperature(about 20 deg F)
About100 Fins(Depends onManufacturer)
3 to 4 Rowsof Tubes(Depends on
Design * )
*Original ‘28 ‘29 had 4 - 5 rows
Round Tubes Original ‘30 - 31 had 3 rows Flat Tubes AA Trucks had 4 rows
Upper Tank
Lower Tank
87 to 102Tubes(The AA Truckhas 136)
TurbulentFlow from Pump
Year Manufacturer Rows Tubes28-29 Ford 4 9429 Flintlock 4 10029 McCord 5 87
Year Manufacturer Rows Tubes30 - 31 Ford 3 102
Round Tube Radiators *
Flat Tube Radiators
Commercial Truck Radiators
Year Manufacturer Rows Tubes30 - 31 Ford 4 136
1928 - 1929 Air FlowTurbulent - RandomInefficient. RoundTubes have poor heatconduction to fins
1930 - 1931 Air FlowStreamlined - MoreEfficient. Flat Tubesincrease conductionto fins.
Ford
RADIATOR Types
* After 1930ReplacementRadiators for1928 - 1929Models wereFlat TubeDesigns
Most Model ARadiators thatare availabletoday are 3 rowFlat tubeA commonupgrade is touse a 4 rowAKA “4 core”radiator basedon the 30 - 31AA TruckRadiator
Ford
REPLACEMENT RADIATOREfficiency
5 6 7 8 9 10Fins per Inch
-20
0
20
40
60
80
100
120
140
160
180
200
Perc
en
t (%
) In
cre
ase o
ver
Ori
gin
al
Bert’s Model A4 Row Flat Tube Radiator
11
Round Tube Replacement
3 Row R
adiators
Flat Tube Replacement
3 Row Radiators
-20
0
20
40
60
80
100
120
140
160
180
200
Bert’s Model A4 Row Flat Tube Radiator
Radiator Efficiency Depends on the # of Fins per Inch
Flat Tube 4 ro
w Radiators
Flat Tube Replacement
3 Row Radiators
Original AA4 Row Radiator
Mail Order Parts Vendors offer a wide variety ofradiators with various fin/inch and tube configurations
1928 - 1929 1930 - 1931
Original OriginalPerc
en
t (%
) In
cre
ase o
ver
Ori
gin
al
Fins per Inch5 6 7 8 9 10 11
Remove MetalWater Pipe
Fit a Plug intoLower Hose
Drain Coolantfrom System
Fill Radiatorwith 1 ½ Galof Water *
Fill to justbelow inletfrom engineLeave cap off
TEST
Remove Plugand RecordTime to Drain
A Three Core Radiatorshould drain in lessthan 4 seconds if itis in good repair.
Replace or RepairRadiator if more than 5 seconds
Ford
A Simple RADIATOR Test
PREP
* The Capacity of theModel A CoolantSystem is about 3 GallonsAbout ½ of it is inthe Radiator at anygiven time … Less for28 - 29 … More for AAtrucks
Ford
ThermostatsDo we need ‘ em ?
Thermostats are used in Modern Cars to maintain aneven engine temperature and give a quick warmup
The Model A Ford was designed without a thermostat
Thermostat
Modern cars haveBypass Valve
Water Pumpat the coolwater inlet
Water Pumpat the hotwater outlet
Modern Engine Model A Ford Engine
No thermostatNo Bypass Valve
Ford
ThermostatsWhat do they do ?
A Thermostat remainsclosed until a temperatureset point is reached (e.g. 160 deg F)
The Thermostat then opensin proportion to the temp ofthe coolant until a maximumis reached usually 20 - 25deg F above the set point
Thermostats regulate the bulk coolant temperature overa range of about 20 deg F by restricting the flow rateinto the top of the radiator
Ford
Were there Thermostatsin the 1930’s
Thermostatic control of engine coolants have beenused since before the Model T
In the early history of auto manufacturing a debateraged between pumped circulation with thermostatsand thermo-syphon systems without.
Henry Ford with his motto of simplicity came downon the side of the thermo syphon system and usedit on the T and on the A
Short Answer: YES
Until the advent of pressurized systems thermostatswere designed as a brass bellows containing a liquidwhich changed to a gas at a particular temperature
After coolant systems were pressurized thermostatswere designed with an expanding wax pellet.
Ford
Modern Car Vs Model ATemperature Regulation
195
160
Time Time
Heat Load
Coolant Temp
Heat Load
Coolant Temp
170
190
Clo
sed
Open
Clo
sed
Open
Engine Coolant Temp at Inlet to Radiator controlledto a narrow operating rangeby opening and closing ofthe Thermostat (TS)
Engine Coolant Temp at Inlet to Radiator controlledby the Thermo Syphon actionof the Model A cooling system
MODERN CAR WITH TS MODEL A WITHOUT TS
Th
erm
osta
tS
et
Poin
t
180DesiredOperatingRange
Clo
sed
Ford
Model A Ford Parts VendorsSell Thermostats
Modern CarThermostat
Model A Ford Thermostatis a Modern Car Thermostatwelded within a thin Stainless Steel Cylinder to prevent rotation within the radiator hose.
Most Vendors Sellboth 160 deg Fand 180 deg FThermostats
WARNING: 180 deg F Thermostats are not fully openuntil 200 deg F which is the boiling point at Denver
ThermostatValve CLOSED
Bypass ValveOPEN Water Pump
cavitating NOcoolant flow
ThermostatValve CLOSED
MODERN CARS BYPASS have a valve which allows circulation ofcoolant when the radiator is not being used to prevent local hot spotformation. Heated water is forcedto the thermostat
Ford
The Model A is NOT designedfor the use of a thermostat
The water pump cannotcirculate coolant when the thermostatis closed. locallyuntil the coolant heat at the inlet tothe radiator reaches the set point.Heated water is not forced to thethermostat
MODEL A
Hot Spots develop
Ford
Hot Spot Formation in aModel A with a Thermostat
Modern Car withThermostat Closed
Until Thermostat OpensCoolant Flow with Bypass Valve
Model A withThermostat Closed
Until Thermostat OpensNo Flow
NucleateBoiling atSurface pulledinto CoolantStream
NucleateBoiling atSurface isstagnate, formsVapor BarrierFLOW
Steam BubblesAbsorbed intoCoolant
Steam Bubblesaccumulate inpockets
Ford
Temperature ProfilesWith and Without Thermostat
160
Time
Heat Load
170
190
MODEL Awith Thermostat
Th
erm
osta
tS
et
Poin
t
180
Open
ing
Clo
sed
160 degThermostatwill be full Openat 180 deg Fand Stay Open
200210
Temperatureprofile withoutthermostat
Temperatureprofile withthermostat
DesiredOperating
Range
- The use of a thermostat will allow heat up faster from cold start times
- Running temperatures will be higher due to the obstruction in the flow at the inlet to the radiator
- During the time the thermostat is closed the water pump will cavitate and not circulate water in the water jackets causing local hot spots which can cause damage
- No real advantage for use of a thermostat
BP atfront range
Average Varying Heat Load
Ford
Temperature ProfilesWith and Without Thermostat
Wildly Varying Heat Load
160
Time
170
190
Th
erm
osta
tS
et
Poin
t
180
Open
or
Part
ly O
pen
Clo
sed
Thermostatfull Open at180 deg F
200210
DesiredOperating
Range
PROS
Clo
sed
Clo
sed
Open
or
Part
ly O
pen
Wildly varying heat loadcauses the thermostat to openand close often to provide ahigher and more even temp
Better engine performance
With Nothermostat
CONS160 deg F thermostat is wideopen at 180 deg. Further cooling control is dependent on Thermo Syphon … Temp mayexceed boiling point
Operating the engine for anextended time with the TSclosed stops coolant flow andcreates Hot Spots which canpotentially damage the engine
Ford
Temperature ProfilesWith and Without Thermostat
Cold Blooded Model A
160
Time
Heat Load
170
190
Cold Running MODEL A
180
200210
Temperatureprofile withoutthermostat
Temperatureprofile withthermostat
DesiredOperating
Range
ConclusionIf your Model A is operatingin a cold range of 140 - 160 deg F a thermostat can raisethe overall temperature
BP atfront range
150140
COLDOperating
Range
Gives better performance
Much shortened warmup
Thermostat will cycle closedor partially closed much ofthe time - issue: Hot Spots
Same effect can be had bycovering up a portion of theradiator - especially in thewinter
Ford
Use A Thermostat ?Conclusion
WARNING: 180 deg F Thermostats are not fully openuntil 200 deg F which is the boiling point at Denver
It depends … Some cars benefit others suffer
The Safest Approach is to not use a thermostat
There are better ways to squeeze that last horsepowerout of the Model A Engine
For winter driving you can run hotter by covering up3 to 5 inches of radiator fins in the engine compartmentto raise the bulk temperature without a thermostat
Under most conditions the thermostat is wide open
If your thermostat is cycling on and off worry aboutHot Spots developing with potential engine damage
Ford
BREAK
Measuring Temperature
Next
Cooling System Maintenance
Ford
Temperature Indicators
Sender Unit Receiver Unit
TEMPERATURE GAUGE MOTOMETER
WILL ACCURATELYTELL YOU THE
ENGINE COOLANTTEMPERATURE
TELLS YOU THERELATIVE VAPOR TEMP
OF THE AIR ABOVETHE COOLANT
Indication of temperaturecontinuous and accurate
Dual gauges are for Oilpressure and water temp
Not calibrated in deg FUsually reads betweentwo lines on the case. Arapid jump to “Danger” shows steam & boiling
Ford
Maintenance Methods
1931 Ford Instruction Book recommends “occasionally”
- Open petcock on radiator, put hose in filler- Let water run until it comes out clear
MAFCA Recommends FlushRadiator every 2000 miles
- Does not specify method of flushing or what to use- Run engine for 10 minutes before draining
DYKES Recommends FlushRadiator every Spring
- Disconnect inlet and outlet hoses- Run tap water through radiator and engine
MODERN Car forums
- Drain Fluid then pour in a Radiator Cleaning Fluid- Run car until HOT then drain and flush with water
Ford
Scale and Crud Removal
DYKES Motor Manual 1929
Use hot water with 1 cup of Washing or Bakingsoda (Washing Soda is Sal Soda) to 2 gallons water
Start Car and Run for 15 min with spark retarded
Drain and flush with water. Back Flush
For hard deposits - use 1 quart Muratic Acid to 5 galwater circulated slowly at idle for 5 minutes.
Other CRAZY formulas from Model A Websites
One pound Sal Soda to Model A radiator & Enginedrive for 1 hour - drain and refill
Contents of 3 or 4 two liter Coke bottles plus waterRun 4 hours. Drain & fill with water run 15 min thendrain and refill.
Ford
Back Flush Technique
Back Flushing can remove crud from plugged pockets
LowerHose
UpperHose
WaterPumpBlock offPlate
After cleaning using your “preferred method” you shouldBack Flush the engine.
Ford
Recommended Cooling System Reading
Dykes Automobile Enclyclopedia - 1929
Auto Mechanics Fundamentals - Stockel - 1969
Automotive Mechanics - Crouse - 1970
The Model A Ford - Victor Page - 1931
Model A Ford Troubleshooting - Les Andrews - 2000
Internal Combustion Engines - Rajput - 2005
Heat Transfer in Engines - Kirkpatrick - 2010
Website Information
What Coolant to Use - www.rockymountainmodelaclub.org
Coolant Seminar - www.rockymountainmodelaclub.org WaterWetter Info - www.redlineoil.com
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