The engine cleaning composition according to the invention comprises at least one primary surfactant selected from nonionic and amphoteric surfactants; at least one glycol; tar acid; one or more pH buffer acids selected from orthophosphoric, phosphonic, glycolic, gluconic, glucoheptonic and citric acids; and deionised water.

The primary surfactant is a main cleaning and dispersing component. Thermal stability is an important and preferred property, e. g. for temperatures of up to 300°C which can be achieved within an engine. The absence of highly active substituent groups such as halides, sulfates and sulfonates is also important and preferred since these encourage erosion at

high temperatures. The presence of amino or amide groups in the surfactant can actively prevent corrosion of the metal surfaces being cleaned. A preferred class of primary surfactants comprises the ethoxylated amines and ethoxylated amides, for example ethoxylated cocoamine, Ethylan TC-fatty amide, Ethylan TM-fatty amide, and Imbentin-cocodiethanolamide.

Other suitable nonionic and amphoteric surfactants include the betaines, glycines and polyethoxylated alkyl ethers and their derivatives.

Preferred ethoxylated amines for use as or in the primary surfactant for the composition of the present invention are of the formula wherein R is an alkyl group having 6 to 20, preferably 12-18 carbon atoms, and x and y are integers whose sum ranges from 2 to 50, preferably from 8 to 20, most suitably from 14 to 16.

Preferred ethoxylated amides for this purpose are of the same formula but with replaced by Suitable ethoxylated amines for use as or in the primary surfactant in the present invention may be obtained from a

large number of commercial suppliers. For example, there may be utilized ethoxylated amines/amides manufactured by Croda Chemicals Ltd. of North Humberside, England under the trademark "Crodamets", or by Lankro Chemicals Ltd of Manchester, England under the trademark"Ethylan"-e. g."Ethylan TC"and"Ethylan TT-15". Rohm and Haas Company of Philadelphia PA markets surfactants of this category under the trademark"Triton RW", "Triton RW-100"being particularly suitable. Also suitable are surfactants sold under the trademark"Ethomeen", in particular "Ethomeen C-25", manufactured by Armour and Co., Chemical Division of Chicago. Ethomeen C-25 contains 15 mols of ethylene oxide on average. The fatty acid component of the Ethomeen is a mixture of CF through C18 acids having approximately 50% by weight of lauryl (C12) residue and approximately 20% by weight of myristyl (C14) residue. A particularly preferred primary surfactant comprises ethoxylated cocoamine which with its appropriate chain length, and preferably with 15 mole ethoxylation (i. e. x + y = 15 in the above formula), can optimise cleaning performance.

The glycols act as high temperature carriers which are stable and able to remain liquid at high temperatures so as to keep the remainder of the ingredients of the composition in solution for longer. This allows the composition to clean in the high temperature environments encountered in engines. The

glycol component may have anti-freeze properties which are beneficial for storage in cold climates. The glycol component may also have surfactant properties to assist in cleaning and dispersion, and it may also dissolve organic soils.

Particularly preferred glycols for use in the composition according to the invention are mono-, di-, and tri-propylene glycol and polyethylene glycol. Other suitable glycols include for example monoethylene glycol and polyhexylene glycol.

The tar acid in the composition is able to penetrate and disperse carbon deposits commonly found within engines. Tar acids generally have boiling points in the range of 230-280°C.

They are generally derived from the middle oil range in the distillation of coal tar by reaction with caustic soda solution, removal from the tar fraction, followed by purification recovery from the aqueous solution by acidification. These tar acids are usually a complex mixture of diethyl phenols/methyl substituted dihydric phenols/propyl and butyl phenols/indenols/naphthols and tetralols. A preferred tar acid component for use in the invention is cresylic acid.

The deionoised water preferably has a conductivity of less 1 microsiemen.

The buffer acid component, one or more of the acids (other

than tar acid) listed above, is employed to buffer the pH of the composition to the required value, which is usually pH 7 to 9 or pH 7 1. This acid component may also act in similar fashion to the tar acid and/or to chelate metal ions from the engine soil, thus assisting the cleaning performance of the composition.

The composition according to the invention preferably includes at least one inhibitor-to inhibit metal corrosion and/or scale. The inhibitor suitably comprises at least one compound selected from organopolyphosphonic acids and/or at least one compound selected from dialkylamides of long chain unsaturated fatty acids.

The organopolyphosphonic acids are of formula R [P (OH) 2O] n, where R is an n-valent organic moiety. R could for example be the divalent group 1-hydroxylethylidene, giving 1- hydroxyethylidene (1, l-diphosphonic acid), compound (1) of the following formula or it could be the trivalent group trimethyleneamino, giving amino tri (methylenephosphonic acid), compound (2) of the following formula (2)

Other di-, tri-and higher valent organic moieties R are possible, having correspondingly 2,3, or more phosphonic acid groups attached thereto. A currently preferred organopoly- phosphonic acid inhinitor for use in the invention contains equal or nearly equal volumes of compounds (1) and (2) above.

Suitable organo-polyphosphonic acid inhibitors for use in the invention are available from the company Solutia of Ghent, Belgium under the trade name DEQUEST. Amongst the DEQUEST products available, DEQUEST 2000 is an aqueous solution of compound (1) above and DEQUEST 2010 is an aqueous solution of compound (2) above; these solutions can for example be combined in appropriate proportions to give a mixture containing about equal volumes of compounds (1) and (2) above. The organopolyphosphonic acids are useful as inhibitors in compositions for cleaning cast iron internal combustion engines.

Amongst the dialkylamide inhibitor compounds, the

dimethylamide compounds are preferred. The hydrocarbon chain of the long chain unsaturated fatty acid is for example of 14 to 20 carbon atoms and a Cl, hydrocarbon chain is one which is particularly suitable. Preferably the hydrocarbon chain has one or two sites of unsaturation. Mixtures of two or more dialkylamide inhibitors may be used. Preferred compounds for use according to the invention are N, N-dimethyloleamide, compound (3) of the following formula and N, N-dimethyllinoleamide, compound (4) of the following formula Compounds (3) and (4) may be employed in admixture in approximately equal amounts by volume-e. g. in a volume ratio of 10 to 9. A suitable dialkylamide inhibitor for use in the invention is available under the trade name DMAD from Buckman Laboratories Limited of London; DMAD is a dimethylamide mixture consisting mainly of compounds (3) and (4) above in a volume ratio of about 10 to 9, together with a small amount (e. g.

about 5-*6) of amides of saturated fatty acids. Compositions according to the invention containing dialkylamide inhibitor are particularly useful for cleaning internal combustion engines containing alumunium components.

The composition according to the invention may also contain a small amount of other additive or additives-e. g. acetic acid and/or ethylenediaminetetraacetic acid. The presence or absence of the latter additive (s), the presence of absence of organopolyphosphonic acid inhibitor, and the amount of tar acid employed, will affect the amount of specified pH buffer acid required to buffer the composition to the required pH (preferably 7 to 9).

Herein the amounts and proportions of components in the cleaning composition of the present invention are expressed as parts and % by volume. The composition according to the invention suitably contains, by volume, from 0.5 to 10 parts of the primary surfactant, from 0.5 to 20 parts of glycol, from 0.08 to 1.0 parts of tar acid, and a total of up to 1 part of buffer acid (s) selected from orthophosphoric, phosphonic, glycolic, gluconic, glucoheptonic and citric acids. The amount of organopolyphosphonic acid inhibitor, when present, is suitably from 0.2 to 10 parts by volume; likewise, the amount of dialkylamide inhibitor, when present, is suitably from 0.2

to 10 parts by volume; where both types of inhibitor are present their amounts may be the same or different. The amount of acetic acid and/or ethylenediaminetetraacetic acid, when present, is preferably 1 part by volume or less. For use as an internal combustion engine cleaner, the composition with the above amounts of ingredients preferably contains sufficient deionised water to give a total composition of 100 parts by volume-i. e. the above parts by volume become volume percent, with the balance of the composition being deionised water.

However, the composition may be supplied initially in more concentrated form, with the ingredients in corresponding proportion, to be diluted appropriately with deionised water for use.

The cleaning composition according to the invention, injected into the air intake of a running engine, can penetrate and disperse soot, silica, scale and hardened carbonation deposits as well as accumulated deposits of atmospheric salts and dust, sulfur, metallic soil, vanadium oxide and oil and grease residues etc., converting them to a fine dry powder which is carried harmlessly from the engine and out through the exhaust system. The small size of sprayed droplets and the low kinetic energy ensure that there is no damage to moving parts.

The composition is vaporised in the combustion chamber, allowing it to remain effective throughout the exhaust system;

during combustion, the deionised water is converted to water vapour, leaving the active ingredients to continue cleaning the exhaust ports and the exhaust. An engine clean with a composition according to. the invention can reduce emissions of exhaust soot by up to 90%, and of carbon monoxide, nitrous oxide and hydrocarbons by up to 50%, increasing engine power delivery and reducing fuel consumption by as much as 20%. Such cleaning can give easier starting from cold, smoother running, easier gear change, better acceleration and reduced servicing costs. The compositions according to the invention are non- toxic and biodegradable and have no harmful affects on engine components or lubricating oils. One clean of a typical motor car petrol or diesel engine may require the injection of about 250 ml of the fluid composition into the air intake of the running engine, but larger volumes may be required for larger automobile engines.

The invention permits reduction of operational costs of automative petrol and diesel engines by the in-service removal of efficiency-reducing deposits from the air intake, combustion chambers and exhaust; once injected, the composition is carried into the engine by the air stream and then out by the exhaust gases.

The efficiency of turbo charged diesel engine gradually

deteriorates as atmospheric deposits accumulate on the turbo- charger compressor. The deposits reduce the air supply to the engine causing incomplete fuel combustion, which produces soot particles that are deposited on the turbocharger turbine. If the engine is inter cooled this effect is more noticeable as the atmospheric deposits restrict the air flow through the cooler. The deposits on the turbocharger turbine reduce its speed, which means it delivers less air to the engine, thereby increasing the production of burnt fuel deposits and further reducing efficiency. The invention can break this efficiency reducing circle by removing the accumulated deposits from the turbocharger, intercooler, combustion chamber and exhaust. The composition can be injected into the running engine as an atomised spray via a nozzle fitted between the air filter and the turbocharger. Once inside the engine the fluid follows the air passages allowing it to come into contact with the efficiency reducing deposits.

A naturally aspirated diesel engine is dependent on good air flow in order to maintain its rated output. If deposits are allowed to accumulate in the exhaust ports, then the exhaust gases are not properly cleared from the combustion chamber. These residual gases contaminate the fuel/air mixture, which causes poor combustion and the creation of new deposits. In severe cases deposits start to form around the

intake ports creating an obstruction to the incoming fuel air mixture, causing a further reduction in power.

The invention can remove these efficiency reducing deposits, ensuring maximum air flow through the engine and optimum performance. The cleaning composition of the invention can be injected into the running engine in an atomised form via a spray nozzle fitted behind the air filter. The fluid is carried through the engine by the air stream, which allows it to come into contact with the atmospheric and burnt fuel deposits.

The composition according to the invention is preferably applied as a spray, and suitable applicators include pump-up sprays, aerosols and spray guns.

For example, when using a pump sprayer, one may pump up the sprayer to achieve a gentle flow rate of approximately 0.2 litres per minute by turning down the lance delivery jet until a fine mist spray is obtained. This flow rate is perfectly suitable for diesel engines but may prove to be too wet for petrol engines to accept-in which case the spray may be released in short bursts.

For spray gun application, a gravity-fed air gun with

opaque cup may be used. The best overall results may be obtained by using 30 psig air pressure and a 1.1 mm paint nozzle to achieve a flow rate of 0.25 litre per 3 minutes delivery time; 1.2-1.3 mm paint nozzles may be used to obtain a faster flow rate when applied to diesel engines.

For aerosol application a 250 ml aerosol may be used for both petrol and diesel engines. Continual spraying for 1 minute will dispense half the contents or 0.125 litre.

The following Examples identify eight preferred cleaning compositions according to the invention. In each case the percentages are by volume, and the balance of the composition is deionised water having a conductivity of less than 1 microsiemen.

EXAMPLE 1 3% Ethoxylated Cocoamine (15 mole ethoxylation) 20% Monopropylene glycol 0.13% Cresylic acid 0.45 Orthophosphoric acid EXAMPLE 2 3% Ethoxylated Cocoamine (15 mole ethoxylation) 20% Polyethylene glycol

0.13% Cresylic acid 0.45% Glycolic acid EXAMPLE 3 6% Ethoxylated Cocoamine (15 mole ethoxylation) 20% Polyethylene glycol 0.15t Cresylic acid 0.45% Glycolic acid 0.50% phosphonic acid EXAMPLE 4 3% Ethoxylated Cocoamine (15 mole ethoxylation) 20% Dipropylene glycol 0.15% Cresylic acid 0.45% Glycolic acid 0.50% EDTA (ethylenediaminetetraacetic acid) EXAMPLE 5 This composition is the same as that of Example 4 except for the substitution of tripropylene glycol for dipropylene glycol.

EXAMPLE 6 This composition is the same as that of Example 1 except that it contains 2% of a 50/50 v/v mixture of 1-

hydroxyethylidene (1,1-diphosphonic acid) and tri (methylenephosphonic acid).

EXAMPLE 7 This composition is the same as that of Example 1 except that it additionally contains 2% of a 10-9 v/v mixture of N, N- dimethyloleamide and N, N-dimethyllinoleamide.

EXAMPLE 8 This composition is the same as that of Example 6 except that it additionally contains 2% of a 10-9 v/v mixture of N, N- dimethyloleamide and N, N-dimethyllinoleamide.