Manual on Selection and Use of Engine Coolants
Contents
1. TABLE 2 Typical Physical Properties of Coolant Compounds 4 Methyl Ethylene Property Water Alcohol Glycol Specific Gravity 68 68 F 20 20 C 1 00 0 7924 1 1155 Specific Heat 77 F 25 C cal g C 0 99765 0 600 0 574 Freezing Point C Pure 32 F 0 C 144 F 97 C 9 F 13 3 C 50 water solution ods 48 F 44 5 C 34 F 36 6 C Boiling Point 100 212 F 100 C 148 F 64 5 C 387 F 197 3 C 50 water solution Kaw 76 F 24 4 C 225 F 107 2 C Vapor Pressure 68 F 20 C mm Hg 17 535 96 1 0 12 Flash Point open cup 3 60 F 15 6 C 240 F 115 6 C Viscosity 68 F 20 C cP 101 0 59 20 9 MNL6 EB May 1989 8 MANUAL ON ENGINE COOLANTS results Do not mix engine coolant of different bases To do so would make it impossible to determine freeze boilover protection using field instruments The freezing point of an engine coolant is the temperature at which the first ice crystals form A solution may be cooled a few degrees below this temperature before flow of coolant is im peded To avoid engine damage from freeze up it is important that sufficient glycol engine coolant concentration be used to provide protection to the lowest expected temperature Boiling point has taken on as much significance as freezing point because of the higher operating tem perature in the modern engine It is no longer safe to use low boiling point fluids Thus the concentration and t2. 68 wil adversely affect heat transfer raise freezing point and may cause inhibitors to precipitate from the coolant when the engine is operating Consult your owner s manual to ensure that any air eliminators are used properly Generally the procedure is to close tightly all drain openings pour in engine coolant concentrate then fill with water of good quality to the proper level Also fill the coolant recovery system reservoir to the proper level with properly diluted engine coolant see Fig 6 Avoid use of water containing excessive amounts of minerals impurities or suspended matter With heater controls set on high run the engine until it reaches operating temperature This procedure will release any trapped air and mix the coolant Allow the engine to cool and inspect the coolant level in the recovery system reservoir If necessary add more properly di luted engine coolant Do not overfill Checking Freezing Point Boiling Point A variety of field testers are available for checking the freezing point of the engine coolant Based on an ASTM study 6 the refractometer tester which measures refractive index is the most accurate for checking the freezing point Check Accuracy of Tester Test the instrument with solutions of known freezing protection A 33 solution of ethylene glycol engine coolant in water protects to 0 F 18 C and a 50 solution should indicate 34 F 37 C protection MNL6 EB May 1989 M
3. as ASTM Specification for Ethylene Glycol Base Engine Coolant D 3306 Any high quality en gine coolant must pass the requirements of this specification The New Role of the Coolant Years ago water was considered to be the best choice for engine cooling and engine designers used water as the baseline fluid in developing cooling system parameters Beginning in the early 1960s and continuing today engines are designed to operate throughout the year on ethylene glycol engine coolant Today 44 to 55 concentrations of inhibited ethylene glycol engine cool ant are installed in new cars on the production line Most major engine coolant marketers rec ommend a 50 concentration for year round use An important property of today s engine coolant that is now being more fully utilized is its higher boiling point A 50 concentration of ethylene glyco coolant raises the boiling point of water 15 F 9 C See Table 1 for details The higher boiling point of glycol engine coolant makes possible the higher engine operating temperatures of today s automotive engine The maximum possible heat transfer capacity of a given cooling system is reached when the coolant entering the radiator is at boiling temperature and at the design pressure of the cooling system Axiomatically it is then evident that raising the boiling point temperature of the cool ant will increase the heat transfer capability of the cooling system This is achieved by the in crease i
4. component When mixed with water it depresses the freezing point and raises the boiling point When glyco base coolant is used at the proper concentration it will provide excellent cooling performance over a wide temperature range Only antifreeze grade ethylene glycol conforming to ASTM Specification for Anti Freeze Grade Ethylene Glycol E 1177 shall be used to formulate antifreeze coolant concentrates Corrosion Inhibitors Unless properly inhibited ethylene glycol water solutions are corrosive MANUAL ON ENGINE COOLANTS 5 FIG 2 Engine Dynamometer Test Equipment This is the third step in a comprehensive four step eval uation program consisting of glassware simulated service engine dynamometer and vehicle testing 6 MANUAL ON ENGINE COOLANTS to metals in the cooling system Inhibitors are chemical compounds that protect metals from corrosion A balanced formulation is composed of many inhibitors all required to protect the various metals present in the modern cooling system Some typical inhibitors that are used in engine coolants are borates phosphates nitrites nitrates silicates mercaptobenzothiazole tolyltriazole and benzotriazole In addition to direct inhibition these chemical additives pro vide a buffering action and alkaline reserve Maintaining the coolant in an alkaline condition is necessary to neutralize acidic products that may be formed by heat induced deterioration of the coolant or by entry into the coolant
5. if the original coolant concentration is maintained and the cooling system kept clean the coolant service life will be extended While this may be true in some cases the habits of motorists as well as the everyday practices of service station attendants make a two year recommendation impractical Cooling System Chemicals Stop Leaks Cooling system leakage may develop as a result of the following 1 loose cylinder head or other gasketed joints 2 loose hose clamps 3 fracture of radiator seams and joints 4 corrosion perforation of radiator tubes or other thin walls of the system 5 deterioration of hoses or gas kets and 6 corrosion of metal joints Since leaks have a tendency to get worse rather than better the best way to assure permanent correction is through mechanical servicing or replace ment of leaking parts Copyright 1989 by ASTM International www astin org MNL6 EB May 1989 MANUAL ON ENGINE COOLANTS 11 FIG 6 Insufficient antifreeze coolant protection or incomplete mixing of solution may result in slush ice freezeup in the radiator stoppage of circulation loss of coolant through the overflow and serious engine overheating Freezing point testing of coolant in vehicle engines should be conducted after approximately one hour of engine operation Sample the coolant after the engine has cooled Use caution when removing the radiator pressure cap Carefully turn to first notch to vent system pressure then remove
6. ANUAL ON ENGINE COOLANTS 11 FIG 6 Insufficient antifreeze coolant protection or incomplete mixing of solution may result in slush ice freezeup in the radiator stoppage of circulation loss of coolant through the overflow and serious engine overheating Freezing point testing of coolant in vehicle engines should be conducted after approximately one hour of engine operation Sample the coolant after the engine has cooled Use caution when removing the radiator pressure cap Carefully turn to first notch to vent system pressure then remove cap If coolant overflows when cap is vented immediately retighten and permit system to further cool If additions are made run the engine to ensure adequate mixing prior to freez ing point testing of coolant Before reading a hydrometer tester fill and empty it several times to warm it up Carefully read instructions furnished with each tester Recommended Period of Use Car manufacturers recommend that the factory fill coolant be used for one to two years Pre vious surveys 7 on the performance of coolants in automotive service indicated that about one third showed appreciable loss of freezing protection loss of inhibitor reserve and rust in solu tion at the end of one year Before two full years most coolants require change Based on these data major engine coolant manufacturers recommend that their products be used for one year preferably changing each Spring or Fall It can be argued that
7. Manual on Selection and Use of Engine Coolants and Cooling System Chemicals 4th Edition Joseph A Lima and George R Otterman editors ASTM Manual Series MNL 6 Revision of STP 120B ASTM 1916 Race Street Phildelphia PA 19103 Library of Congress Cataloging in Publication Data Manual on selection and use of engine coolants and cooling system chemicals Joseph A Lima and George R Otterman editors 4th ed ASTM manual series MNL 6 Special technical publication STP 120 ISBN 0 8031 1265 3 1 Anti freeze solutions I Lima Joseph A II Otterman George R III Series IV Series ASTM special technical publication 120 TP362 M36 1988 629 2 56 dc19 89 342 CIP 1989 by American Society for Testing and Materials ASTM Publication Code Number PCN 28 006089 15 NOTE The Society is not responsible as a body for the statements and opinions advanced in this publication Printed in Baltimore MD May 1989 Contents Introduction The Engine Cooling System Purpose Need for Antifreeze Coolant The New Role of the Coolant Antifreeze Coolants Types of Antifreeze Coolant Antifreeze Coolant Composition Properties of Antifreeze Coolants Water Quality Installation and Service Preparing the Cooling System Installing the Engine Coolant Concentrate Checking Freezing Point Boiling Point Recommended Period of Use Cooling System Chemicals Stop Leaks Cleaners Antirusts Cool Additives Supplemen
8. ality Clean clear potable water low in chloride and hardness is generally acceptable Avoid using any water that is brackish or that you couldn t drink Deionized or distilled water is ideal to dilute engine coolant concentrate for use With properly inhibited engine coolant water meeting the require ments outlined in Table 3 is considered suitable for use Water exceeding these levels can cause excessive scale sludge deposits and increased corrosion potential TABLE 3 Water Quality Property Requirement Total Solids Maximum 340 ppm 20 grains gal Total Hardness Maximum 170 ppm 10 grains gal Chloride as Cl Maximum 40 ppm 2 5 grains gal Sulfate as SO Maximum 100 ppm 5 8 grains gal Installation and Service Preparing the Cooling System Inspection and Test Before installing any engine coolant the cooling system should be in spected and necessary service work completed The essential Spring and Fall cooling system service 5 is as follows 1 Check coolant concentration 50 by volume optimum 2 Check coolant level and condition Change if dirty or over a year old 3 Before starting engine check for signs of coolant leakage such as color stains near hose connections and coolant spots on floor or driveway etc Copyright 1989 by ASTM International www astin org P X MANUAL ON ENGINE COOLANTS 9 4 Test pressure cap inspect radiator filler neck for dirt 5 Inspect hoses Tighten
9. all hose connections including those to the expansion tank to protect against coolant loss 6 Test thermostat if engine is running too hot or too cold NOTE Steps 3 through 6 should be performed by qualified automotive service personnel Water Flushing Draining your cooling system through the radiator drain cock will remove only about half of the coolant from the cooling system For this reason repeated water flushings are necessary to flush all traces of old coolant A special tee and fittings may be purchased to completely flush the cooling system Fig 4 NOTE Disposal of depleted engine coolant is under study by state and federal environmental au thorities While biodegradable ethylene glycol can be toxic to man and animals when con sumed in sufficient quantity Do not leave engine coolant where accidental ingestion can occur Consult with your local environmental agency for current disposal practices in your area Cleaning If the drained coolant is rust colored or the radiator as viewed through the filler neck is rusty the system should be cleaned A flush type product will facilitate removal of sludge and loosely adherent rust However if the system is badly rusted a heavy duty cooling system cleaner will be required In either case the manufacturer s directions should be carefully followed Mechanical Service Repair all leaks Leakage at the rate of one drop a minute means the loss of 1 gal of solution in six week
10. ant that sufficient glycol engine coolant concentration be used to provide protection to the lowest expected temperature Boiling point has taken on as much significance as freezing point because of the higher operating tem perature in the modern engine It is no longer safe to use low boiling point fluids Thus the concentration and type of coolant used should be based on both freezing and boiling points The best recommendation for the continental United States is to use a 50 solution of ethylene glycol engine coolant year round The chemical properties of an engine coolant are determined in part by the pH or reserve alkalinity of the coolant The pH is indicative of the acidity or alkalinity It is desirable that engine coolants have an alkaline pH greater than 7 5 The degree of alkalinity is defined by reserve alkalinity a number obtained by titration of a known volume of engine coolant with a standard acid solution the higher the number the greater the alkalinity It is a measure of the concentration of inhibitors or other chemicals that have been added which contribute to the alkaline character of the coolant However reserve alkalinity alone does not completely indicate the quality of corrosion inhibition and should not be interpreted to be a complete indication of this quality Corrosion inhibition can only be determined by actual corrosion testing Water Quality Water used to dilute engine coolant concentrate for use must be of high qu
11. cap If coolant overflows when cap is vented immediately retighten and permit system to further cool If additions are made run the engine to ensure adequate mixing prior to freez ing point testing of coolant Before reading a hydrometer tester fill and empty it several times to warm it up Carefully read instructions furnished with each tester Recommended Period of Use Car manufacturers recommend that the factory fill coolant be used for one to two years Pre vious surveys 7 on the performance of coolants in automotive service indicated that about one third showed appreciable loss of freezing protection loss of inhibitor reserve and rust in solu tion at the end of one year Before two full years most coolants require change Based on these data major engine coolant manufacturers recommend that their products be used for one year preferably changing each Spring or Fall It can be argued that if the original coolant concentration is maintained and the cooling system kept clean the coolant service life will be extended While this may be true in some cases the habits of motorists as well as the everyday practices of service station attendants make a two year recommendation impractical Cooling System Chemicals Stop Leaks Cooling system leakage may develop as a result of the following 1 loose cylinder head or other gasketed joints 2 loose hose clamps 3 fracture of radiator seams and joints 4 corrosion perforation of radiator
12. considered suitable for use Water exceeding these levels can cause excessive scale sludge deposits and increased corrosion potential TABLE 3 Water Quality Property Requirement Total Solids Maximum 340 ppm 20 grains gal Total Hardness Maximum 170 ppm 10 grains gal Chloride as Cl Maximum 40 ppm 2 5 grains gal Sulfate as SO Maximum 100 ppm 5 8 grains gal Installation and Service Preparing the Cooling System Inspection and Test Before installing any engine coolant the cooling system should be in spected and necessary service work completed The essential Spring and Fall cooling system service 5 is as follows 1 Check coolant concentration 50 by volume optimum 2 Check coolant level and condition Change if dirty or over a year old 3 Before starting engine check for signs of coolant leakage such as color stains near hose connections and coolant spots on floor or driveway etc Copyright 1989 by ASTM International www astin org P X MNL6 EB May 1989 8 MANUAL ON ENGINE COOLANTS results Do not mix engine coolant of different bases To do so would make it impossible to determine freeze boilover protection using field instruments The freezing point of an engine coolant is the temperature at which the first ice crystals form A solution may be cooled a few degrees below this temperature before flow of coolant is im peded To avoid engine damage from freeze up it is import
13. d published in STP 705 and STP 887 on Engine Coolant Testing Good cooling system maintenance is an important factor in maintaining the efficient operation of a liquid cooled engine Any operation of engines using water alone as the coolant will cause some degree of corrosion Selection and use of proper coolant or coolant treatment for your engine cannot be overemphasized This manual will assist the consumer in selecting quality engine coolants and proper maintenance procedures to ensure efficient and trouble free operation of today s engine cooling systems The procedures and practices described herein have no official status as ASTM standards However Committee D 15 has developed full consensus standards and some of these standards are specifically cited in this manual The full set of the Committee D 15 standards on engine coolants are published in Volume 15 05 of the Annual Book of ASTM Standards This manual may involve hazardous materials operations and equipment and does not pur port to address all of the safety problems associated with their use It is the responsibility of the user of this manual to establish appropriate safety and health practices and determine the ap plicability of regulatory limitations prior to use The revisions of this manual were prepared by a D 15 task group consisting of the following members N R Cooper Union Carbide Corp R H Faye Dow Chemical Corp J A Lima Houghton Chemical Corp and G R Ott
14. erman General Motors Corp Union Carbide Corp is acknowledged for contributing photographs for this publication The Engine Cooling System Purpose The purpose of an engine cooling system is to remove excess heat produced by engine opera tion and control metal temperatures within safe limits High speed driving with today s engines can produce enough heat energy to melt a 200 Ib 91 kg cast iron engine block in 20 minutes 1 Even operating at moderate speeds the temperatures inside the engine are extremely high Combustion gas temperatures may be as high as 4500 F 2482 C The heads of the exhaust valves may be red hot and the temperature of lubricated parts such as pistons may run 200 F 93 C or more above the boiling point of water When metal temperatures are not controlled by adequate cooling the consequences are lubrication failure and serious engine damage This is especially true with engines having aluminum heads Need for Antifreeze Coolant Liquid cooled internal combustion engines require a circulating coolant to remove excess heat While water is an effective heat transfer fluid it has serious shortcomings as an engine 1 Copyright 1989 by ASTM International www astin org MNL6 EB May 1989 Introduction This ASTM manual has been developed by Committee D 15 on Engine Coolants and is a revision to ASTM Special Technical Publication STP 120B This publication provides con sumers with practical informati
15. gine coolant adversely affects cooling capability and corrosion inhibitor stability Heat from engine operation causes corro sion inhibitors to precipitate from the coolant making it unable to protect engine components from corrosion and possibly plugging small cooling passages in the engine and radiator Antifreeze Coolants Although the long standing function of engine coolants is to prevent freezing in the engine cooling system it also must meet other requirements to be satisfactory 3 4 It should 1 have a high boiling point 2 prevent corrosion of cooling system metals 3 effectively transfer heat 4 be chemically stable 5 be miscible with water and 6 be relatively nonflammable It should not adversely affect other materials in the system not foam evaporate or expand excessively A number of materials have been used as freezing point depressants but none satisfy all these requirements However usage and extensive testing have established certain coolant base mate rials as preferable to others Types of Antifreeze Coolant Glycols A properly formulated ethylene glycol coolant can satisfy the requirements of the modern engine cooling system When ethylene glycol coolant is sufficiently diluted with water of good quality it provides good chemical stability and adequately satisfies the requirements out lined earlier Evaporation of glycol is practically nil and loss of engine coolant can only occur from boilover leaking expansi
16. ilicates are very sensitive to gelling or dropping out FIG 3 Exhaust gas leakage into the cooling system can cause foaming overflow loss of coolant over heating and shortened inhibitor life with subsequent corrosion and rust clogging MANUAL ON ENGINE COOLANTS 7 of solution if the engine coolant is over concentrated or left in service too long Never use more than a 68 concentration of engine coolant Generally 50 is the recommended concentra tion Changing your engine coolant annually will help ensure your coolant is maintained in optimal condition Foam Suppressor Bubbles that accumulate in the system through the introduction of ex haust gases or air entrainment are detrimental to the function of the cooling system Higher alcohols or other organic chemicals are added to engine coolant to suppress the formation of foam These substances are surface active agents that affect the surface tension of the liquid causing the bubbles to break Dye A dye is added to the engine coolant to differentiate it from other functional fluids such as automatic transmission fluid brake fluid etc and to signal its presence in the cooling sys tem The dye should remain stable during the period of use and should not affect the appear ance of paint finishes in case of accidental spillage of coolant Water All engine coolant concentrate contains a small amount of water usually less than 5 This includes water of hydration from s
17. lating coolant to remove excess heat While water is an effective heat transfer fluid it has serious shortcomings as an engine 1 Copyright 1989 by ASTM International www astin org 2 MANUAL ON ENGINE COOLANTS coolant It freezes at too high a temperature 32 F 0 C boils at too low a temperature 212 F 100 C and causes corrosion of cooling system metals Various alcohols and glycols can be used as antifreezes and are effective freeze point de pressants for water However because glycols raise the boiling point of water while alcohols lower it only glycol bases are recommended for use by engine manufacturers Corrosion is effectively controlled by using chemical inhibitor systems which are added to the glycol to make a complete coolant concentrate formulation commonly referred to as permanent engine coolant There are many corrosion mechanisms which can take place in today s engines The complex ity has increased with the use of aluminum alloys in the head and block Aluminum used in areas such as the head where large quantities of heat are liberated to the coolant is subject to a unique heat rejection corrosion To protect against the heat rejection corrosion of aluminum a coolant having special corrosion inhibitor systems must be used Follow the recommendations of your vehicle manufacturer concerning engine coolants and be certain the product you select conforms to standard specifications for engine coolant such
18. mized by radiator manufacturing techniques as well as recom mended coolant maintenance practices Antirusts If year round protection is not provided by the use of an inhibited engine coolant such as in some heavy duty engines then it is necessary to add an effective antirust to the coolant water The importance of using a properly inhibited coolant during warm weather is readily appreci ated when it is realized that cooling system corrosion is most severe during this period This is a result of higher engine temperatures along with higher road speeds and mileage During warm weather driving when the thermostat is wide open the high velocity of coolant entering the radiator may increase air entrainment and hence the rate of aeration and subsequent corro sion The prevention of corrosion in the cooling system during warm weather months will help assure satisfactory performance of the engine coolant during the following winter Both soluble chemical and emulsifiable oil type antirusts for use with water are generally available although most of them will not provide the satisfactory corrosion protection provided by a properly inhib ited engine coolant Different proprietary antirusts may not be compatible with each other The manufacturer s directions should always be followed with respect to mixture and dosage In cars equipped with a factory installed air conditioner it is possible to obtain temperatures below 32 F 0 C at the heater co
19. n coolant temperature at the radiator inlet The resulting increase in radiator core aver age temperature generates a greater temperature differentia between the core and the cooling air This markedly increases the radiator cooling capacity 2 Most vehicle and engine coolant manufacturers recommend a 50 vol concentration be used year round This concentration is needed to achieve the engine design cooling capacity to TABLE 1 Boiling Points of Various Concentrations of Ethylene Glycol Boiling Point Ethylene Glycol Concentration Atmospheric 15 psig 103 kPa by Volume Pressure System Pressure 44 224 F 107 C 262 F 128 C 50 227 F 108 C 265 F 129 C 60 232 F 111 C 270 F 132 C 70 238 F 114 C 276 F 136 C Concentrations higher than 68 are not recommended 68 provides maxi mum freezing protection to approximately 92 F 69 C MNL6 EB May 1989 MANUAL ON ENGINE COOLANTS 3 provide a margin of safety against boilover to insure an adequate level of inhibitor concentra tion Fig 1 and to provide freeze protection to 34 F 37 C If greater freeze protection is needed more engine coolant concentrate may be used however the concentration should never exceed 68 Concentrations greater than 68 actually raise the freeze point Undiluted ethyl ene glycol engine coolant freezes at approximately 9 F 13 C In addition to reduced freeze protection over concentrated en
20. nd their inferiority to water glycol coolants as heat transfer agents Furthermore if the engine temperature warning device should malfunction during a cooling system failure these materials will not give the secondary warning of boiling over because of their high boiling points These excessive engine temperatures may burn out engine bearings cause piston seizure warp heads or melt the solder in the radiator Solutions of sugar or honey have also been tried These are unsatisfactory because high con centrations are required to provide adequate freezing protection These solutions are unstable as well as too viscous Laws have been enacted in many states in an attempt to prevent the sale and distribution of deleterious antifreeze products such as salt solutions or petroleum coolants Even ethylene gly col engine coolants must be evaluated by testing and comparison of test results with specifica tions for engine coolant concentrate such as ASTM D 3306 These tests ensure desired levels of antifreeze coolant concentrate and inhibitor are available to adequately protect cooling systems against freezing boilover and corrosion Fig 2 Antifreeze Coolant Composition A properly formulated engine coolant concentrate is composed of several essential ingredi ents including base fluid corrosion inhibitors foam suppressor dye and water Base Fluid This material constitutes the bulk of the concentrate In most cases ethylene glycol is the major
21. oblems associated with their use It is the responsibility of the user of this manual to establish appropriate safety and health practices and determine the ap plicability of regulatory limitations prior to use The revisions of this manual were prepared by a D 15 task group consisting of the following members N R Cooper Union Carbide Corp R H Faye Dow Chemical Corp J A Lima Houghton Chemical Corp and G R Otterman General Motors Corp Union Carbide Corp is acknowledged for contributing photographs for this publication The Engine Cooling System Purpose The purpose of an engine cooling system is to remove excess heat produced by engine opera tion and control metal temperatures within safe limits High speed driving with today s engines can produce enough heat energy to melt a 200 Ib 91 kg cast iron engine block in 20 minutes 1 Even operating at moderate speeds the temperatures inside the engine are extremely high Combustion gas temperatures may be as high as 4500 F 2482 C The heads of the exhaust valves may be red hot and the temperature of lubricated parts such as pistons may run 200 F 93 C or more above the boiling point of water When metal temperatures are not controlled by adequate cooling the consequences are lubrication failure and serious engine damage This is especially true with engines having aluminum heads Need for Antifreeze Coolant Liquid cooled internal combustion engines require a circu
22. of corrosive exhaust gases past leaking cylinder head gaskets Fig 3 Each inhibitor must be present at a sufficient concentration to provide adequate corrosion protection The amount of inhibitor required is affected by a variety of factors including operat ing conditions the corrosivity of the water used for dilution operating temperatures and the length of time at operating temperatures Corrosion inhibition is one of the reasons for main taining the engine coolant at a 50 concentration all year Furthermore inhibitors are de pleted with time through interaction with metals and other substances in the system They must be replenished or replaced The preferred practice is to replace the antifreeze coolant at peri odic intervals because of in service inhibitor depletion or contamination that may have entered the system Select the engine coolant or antirust with care to ensure adequate corrosion protection Use only those products conforming to recognized standards such as ASTM D 3306 for engine cool ant Additionally if your vehicle engine contains major cast aluminum components be certain the engine coolant meets the heat rejection corrosion limits in ASTM specification D 3306 as determined by ASTM Test Method for Corrosion of Cast Aluminum Alloys in Engine Coolants Under Heat Transfer Conditions D 4340 Most engine coolants formulated to provide protection against the heat corrosion of alumi num contain elevated levels of silicate S
23. of water and the danger of loss from boiling or evaporation Alcohol volatilizes from hot surfaces much more readily than gly col coolant and can be a potential fire hazard Methy alcohol liquids are both flammable and poisonous Methyl alcohol vapors are toxic when inhaled at high concentrations Others Methoxy propanol a glycol ether has had limited use in recent years as an engine coolant principally in heavy duty vehicles Its advantage is said to be better compatibility with engine oi should internal leakage occur It has a lower flash point and boiling point than ethyl ene glycol It has not been extensively used in automotive cooling systems because of its higher cost and the present satisfaction with glyco products Several attempts have been made to use other materials as antifreezes Salts such as calcium chloride or sodium acetate depress freezing points but are corrosive They can cause severe corrosive damage to the engine Leakage of these salt solutions can cause short circuiting of the electrical system Petroleum base coolants have been considered for use because of their low freezing point and negligible corrosive effect on cooling system metals Since they are not miscible with water a larger volume of coolant material is required and their use is more costly than other engine coolants They are not recommended because of their adverse effect on hose materials their potential fire hazard at engine operating temperatures a
24. ome of the chemical additives water of reaction produced during formulating water originally present in the base material and water deliber ately added to help dissolve the inhibitors Water must be held at a low level in order that the appropriate freezing protection will be obtained when the engine coolant concentrate is diluted for use with water on the basis of standard tables It should be noted however that some highly watered antifreeze coolants are sold to the unsuspecting motorist The consumer may identify such products by referring to the protection chart on the container An inferior coolant concen trate will show less than the industry standard of 34 F 37 C for a 50 volume solution Properties of Antifreeze Coolants The physical properties of compounds used as engine coolants are quite different and have a determining effect on their suitability for use Physical properties can be used to identify coolant compounds and to determine in part how well the compound will function as a coolant Some typical values for coolant compounds are shown in Table 2 The physical properties that are of most importance to the user of engine coolants are the freezing and boiling points These can be measured accurately in a laboratory or determined indirectly in the field using readily available instruments that indicate the freeze point or boiling point based on specific gravity or refraction of light These instruments give approximate
25. on overfilling or evaporation of water Diethylene glycol or propylene glycol alone can also be used as antifreeze coolants but they are more likely to be mixed with ethylene glycol Their addition is usually restricted to a small percentage of the total glycol content Ethylene glycol base coolants meeting specification requirements of ASTM D 3306 used at 50 concentration offer freezing protection to 34 F 37 C provide a sufficiently high FIG 1 Coolant pump damaged by cavitation erosion corrosion Pitting can be controlled by a properly inhibited antifreeze coolant that is used as directed by the manufacturer Co yright 1989 by ASTM International www astin org P 4 MANUAL ON ENGINE COOLANTS boiling point and effectively inhibit corrosion At a concentration of 68 by volume an ethyl ene glycol base coolant has a freezing point of approximately 92 F 69 C Ethylene glycol is modified sometimes by the addition of glycol ethers such as 2 methoxy ethanol to lower the viscosity at very low temperatures and to prevent freezing of the undiluted engine coolant concentrate Alcohols Methyl alcohol and to a lesser extent ethyl alcohol were used as freezing point depressants for many years Their use now is minimal When properly inhibited alcohol water solutions can be satisfactory coolants only under restricted conditions Alcohol antifreezes fell into disuse because of their low boiling point lower than that
26. on and advice on engine coolants as well as cooling system chemicals such as cleaning compounds and practices antirusts and stop leaks This fourth edition presents new information on coolants containing silicates for the protection of alumi num components in today s engines More detailed information on engine components antifreeze coolants and cooling system maintenance was presented at two Committee D 15 symposia and published in STP 705 and STP 887 on Engine Coolant Testing Good cooling system maintenance is an important factor in maintaining the efficient operation of a liquid cooled engine Any operation of engines using water alone as the coolant will cause some degree of corrosion Selection and use of proper coolant or coolant treatment for your engine cannot be overemphasized This manual will assist the consumer in selecting quality engine coolants and proper maintenance procedures to ensure efficient and trouble free operation of today s engine cooling systems The procedures and practices described herein have no official status as ASTM standards However Committee D 15 has developed full consensus standards and some of these standards are specifically cited in this manual The full set of the Committee D 15 standards on engine coolants are published in Volume 15 05 of the Annual Book of ASTM Standards This manual may involve hazardous materials operations and equipment and does not pur port to address all of the safety pr
27. oys under Heat Transfer Conditions Technical Report No SR 81 11 Research Staff Report Ford Motor Company Dearborn MI 1981 5 Engine Cooling System Care Consumer Fact Sheet Chemical Specialties Manufacturers Associa tion Washington DC 1984 6 A Study of Antifreeze Field Testers Materials Research and Standards Vol 10 No 6 pp 33 35 ASTM June 1970 7 Beynon E Field Performance and Factory Installed Antifreeze Coolants in Passenger Car Service Reprint No 660128 Society of Automotive Engineers New York NY January 1966 8 Maintenance of Automotive Engine Cooling Systems SAE HS 40 Society of Automotive Engi neers New York NY 9 Practice for Testing Engine Coolants in Car and Light Truck Service D 2847 Annual Book of ASTM Standards Vol 15 05 10 Day R Popular Science Vol 198 No 6 June 1971 pp 38 42 11 Automotive Cooling Journal Vol 13 No 6 Nov Dec 1970 pp 6 11
28. re evaporator unit this can cause damage from freezing un less engine coolant is used Today all U S car manufacturers as well as other recognized au thorities recommend the use of ethylene glycol engine coolant year round for proper operation of the engine as well as temperature warning devices 14 MANUAL ON ENGINE COOLANTS Cool Additives Despite the claims of the radiator cool additive manufacturers there are no data at present that substantiate lower operating temperatures or improved heat transfer resulting from the use of these products Their benefits have not been demonstrated by any impartial test organization 2 10 11 These products offer nothing that a properly inhibited ethylene glycol engine cool ant of the type and concentration recommended by the automotive manufacturers does not supply namely low freezing point high boiling point good corrosion inhibition and foam control Most modern engines are designed to run with inhibited ethylene glycol engine coolant year round Operation with either water alone or water with additives is contrary to automotive manufacturers recommendations and may lead to engine failure Supplemental Coolant Additives These are mixtures for use principally in heavy duty engine cooling systems and are designed to supplement the corrosion protection of the engine coolant concentrate being used The addi tional stresses and operational mileage or operational time that heav
29. s A leaky cylinder head joint can cause coolant contamination rapid rusting foaming overflow loss and overheating Engine coolant mixed with engine oil may cause lubrication failure and serious engine damage Fig 5 Defective water pump seals can also contribute to corrosion foaming and overflow loss WATER HOSE DEFLECTOR SPECIAL TEE amp HOSE COUPLER HEATER INLET HOSE 4 THERMOSTAT IN PLACE HEATER HEATER OUTLET HOSE TO PUMP RADIATOR WATER PUMP 7 FIG 4 Flow diagram showing simplified method of flushing the cooling system 10 MANUAL ON ENGINE COOLANTS FIG 5 Leakage of coolant into the engine can occur through a loose cylinder head joint or cracks in the cylinder block or head Either water or antifreeze coolant mixed with engine oil in sufficient quantities may cause lubrication failure and serious engine damage Installing the Engine Coolant Concentrate After inspection and completion of required service determine capacity of the cooling system from a cooling system protection chart or car owner s manual A 50 concentration 34 F 37 C freezing protection is generally recommended Recent surveys have shown that over concentration and under concentration are common sources of cooling system problems A minimum concentration of 33 1 3 is required to pro vide minimal corrosion protection Maximum freeze protection is obtained at 68 by volume Concentrations over
30. t replacement of the deterio rated hose may finally result in complete rupture loss of coolant and possibly overheating damage to the engine before the driver is aware of what has taken place Field service experience has proved that stop leak materials cannot be depended upon to correct cylinder head joint leakage due to high combustion pressures at the joint and thermal stresses in the joint metals Cleaners Rust deposits and particulate contaminants in the cooling system may shorten engine coolant inhibitor life as well as reduce cooling efficiency Flushing and cleaning of the cooling system should be carried out prior to installing the new coolant see p 8 section on Installation and Service Procedures for both preventive and corrective cleaning of the cooling system can be found in automotive maintenance literature 1 8 9 Preventive Flush In systems where rust and dirt are found in the presence of grease and oil a cooling system flush with a chelator cleaner is recommended Corrective Cleaning f the cooling system is fouled with rust deposits that cannot be loosened with a preventive flush corrective cleaning using an acid may be necessary It is important that the vehicle or engine manufacturer s recommendations be followed for cleaning and flushing cooling systems Highly alkaline cleaners should not be used in aluminum engines or radiators because of their corrosive effect on the aluminum Only cleaners recommended for alumin
31. tal Coolant Additives List of Tables Table 1 Boiling Points of Various Concentrations of Ethylene Glycol Table 2 Typical Physical Properties of Coolant Compounds Table 3 Water Quality List of Figures Figure 1 Coolant Pump Damaged by Cavitation Erosion Corrosion Figure 2 Engine Dynamometer Test Equipment Figure 3 Exhaust Gas Leakage into the Cooling System Figure 4 Flow Diagram Showing Simplified Method of Flushing the Cooling System Figure 5 Leakage of Coolant into the Engine Through a Loose Cylinder Head Joint Figure 6 Siush ice Freezeup in the Radiator Figure 7 Radiator Solder Corrosion Deposits at the Tube to Header Joint as Viewed Through the Filler Neck C ES ES 9 OO Elsias n eN Se 14 14 oof Sy Ha wm mao E MNL6 EB May 1989 Introduction This ASTM manual has been developed by Committee D 15 on Engine Coolants and is a revision to ASTM Special Technical Publication STP 120B This publication provides con sumers with practical information and advice on engine coolants as well as cooling system chemicals such as cleaning compounds and practices antirusts and stop leaks This fourth edition presents new information on coolants containing silicates for the protection of alumi num components in today s engines More detailed information on engine components antifreeze coolants and cooling system maintenance was presented at two Committee D 15 symposia an
32. tubes or other thin walls of the system 5 deterioration of hoses or gas kets and 6 corrosion of metal joints Since leaks have a tendency to get worse rather than better the best way to assure permanent correction is through mechanical servicing or replace ment of leaking parts Copyright 1989 by ASTM International www astin org 12 MANUAL ON ENGINE COOLANTS Stop leak compounds are effective in closing minor leaks After leaks are closed a reserve of stop leak material in the coolant is usually necessary to reseal old leaks opened up by vibration corrosion etc and also to seal any new leaks that may develop Stop leaks should be consid ered as adequate only for short term band aid uses As soon as practical the leak should be properly repaired Most stop leak products consist of small pieces of natural fibers vegetable or inorganic Before considering the use of any particular stop leak preparation its suitability and also com patibility with the coolant in use should be known The solids in stop leak compounds may result in plugging or excessive deposit formation in the cooling system When a leak develops it should be examined to determine the nature and seriousness Stop leaks should not be used as a substitute for mechanical servicing because they may give a false sense of security For instance a stop leak may prevent seepage at a hose connection through cracks developing in the inner lining Continued driving withou
33. um engines and radiators should be used in such vehicles The use of most acid cleaners must be followed by a neutralizer The importance of neutraliz ing these acid cleaning solutions and completely removing the resulting salts from the cooling system by draining and thorough flushing cannot be overemphasized The use of a flushing gun employing compressed air and water wil assist in removing acid residues Field tests have shown that a small quantity of acid cleaner solution left in the cylinder block will deplete coolant inhibition causing a high degree of corrosive attack Contamination of the cooling system by acid cleaning compounds is usually caused by 1 failure to use a neutralizer 2 incomplete draining and flushing of the cylinder block or 3 inadequate flushing of the car heater or other accessories connected to the cooling system Chemical cleaning of a corroded system can open up leaks that were previously plugged by corrosion deposits Even the simplest type of cleaning is time consuming The most practical and economical approach to the maintenance of a cool ing system to prevent corrosion Fig 7 is a good preventive maintenance program which in cludes a fresh filling of the correct well inhibited engine coolant and good quality water each year MANUAL ON ENGINE COOLANTS 13 FIG 7 Radiator solder corrosion deposits at the tube to header joint as viewed through the filler neck This special form of corrosion can be mini
34. y duty engines experience as well as important design differences require use of these supplements according to a regular maintenance schedule Heavy duty equipment owners should consult the engine manufacturers recommendation for coolant and supplemental additive guidelines Automobile engine coolant systems properly protected by engine coolant meeting specifica tion ASTM D 3306 do not require use of supplemental additives Major coolant manufacturers discourage use of these supplements with their coolant in automobile cooling systems Adherence to suggested maintenance schedules and practices including regular coolant sys tem drainage and recharge with properly diluted fresh engine coolant concentrate will provide your automobile cooling system with superior protection against freezing boilover and corro sive attack References 1 Cooling System Service Manual 3rd edition Union Carbide Corporation New York NY 1965 2 Beynon E Cooper N R and Hannigan H D Soap and Chemicals Specialties Vol 47 No 2 pp 44 and No 3 pp 52 February and March 1971 3 Rowe L C Chance R L and Walker M S The Development of an Antifreeze Coolant for Aluminum and Cast Iron Engines General Motors Research Publication GMR 3819 PCP 160 Physical Chemistry Department General Motors Research Laboratories Warren MI October 1981 4 Wiggle R R Hospadaruk V and Tibaudo F M Corrosion of Cast Aluminum All
35. ype of coolant used should be based on both freezing and boiling points The best recommendation for the continental United States is to use a 50 solution of ethylene glycol engine coolant year round The chemical properties of an engine coolant are determined in part by the pH or reserve alkalinity of the coolant The pH is indicative of the acidity or alkalinity It is desirable that engine coolants have an alkaline pH greater than 7 5 The degree of alkalinity is defined by reserve alkalinity a number obtained by titration of a known volume of engine coolant with a standard acid solution the higher the number the greater the alkalinity It is a measure of the concentration of inhibitors or other chemicals that have been added which contribute to the alkaline character of the coolant However reserve alkalinity alone does not completely indicate the quality of corrosion inhibition and should not be interpreted to be a complete indication of this quality Corrosion inhibition can only be determined by actual corrosion testing Water Quality Water used to dilute engine coolant concentrate for use must be of high quality Clean clear potable water low in chloride and hardness is generally acceptable Avoid using any water that is brackish or that you couldn t drink Deionized or distilled water is ideal to dilute engine coolant concentrate for use With properly inhibited engine coolant water meeting the require ments outlined in Table 3 is
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