Cleaning Fuel Bodies By Bruce Smith 101 Cincae the inventrion of thbe carbureto r in Csubstitutinhg the Gereman kupfemr for . iworsst case sctenario rfor a cayrburetor is to re - the late nineteenth and early twentieth There are various standard formulations and Eu - plenish the gasoline in the float bowl after it Scenturies (when Zenith, Pallas, Pier - ropean casting has a zinc content of evaporates, ensuring a good supply of water sat - burg, and SOLEX were pioneering designs), about 95% with 4% aluminum and 1% copper. urated fuel. Carried out over several years, this there has been a need to clean the residues and Most inorganic reactions are based on this zinc sets up the ideal conditions to maximize zinc re - reactants that accumulate during use. The crud content, which can form deposits and lead to actions. The preventative solutions are to en - that forms in and on carburetors and fuel pumps corrosion damage. Extreme examples result in sure that only fresh gas is in the fuel system and generally falls into two categories: organic (from internal corrosion sufficient enough to damage that the carburetor and fuel pump are run dry petroleum residues, grease and oil) and inor - a casting beyond repair. before storing. ganic (from reactants, minerals and A bit of chemistry background is useful to salts). Most of these contaminants can plug jets, understand the processes that occur. Zinc is re - Cleaning Organic & Inorganic Contaminants nozzles, and pathways, preventing proper me - sistant to corrosion if kept reasonably dry. A thin So cleaning an old Zenith or SOLEX carbu - chanical operation. Some can also corrode and layer of zinc oxide naturally forms on the metal retor or a Pierburg fuel pump involves removing degrade the integrity of internal components. surface and will protect it from further corro - both organic deposits and inorganic byproducts. When a car is used on a regular basis, cycling sion. In wet conditions, a white porous residue Methods can be mechanical or chemical and fresh gas through the fuel system, most buildup of zinc carbonate, zinc hydroxide and zinc oxide need to do as little harm as possible. Mechani - will be associated with organic compounds. Re - will form, consuming the zinc and leading to vol - cal cleaning sufficient to reach all surfaces might actions with gasoline, oil and atmospheric con - ume expansion of the residue by a up to 100X. suggest abrasive blasting. This however is a very taminants result in hydrocarbon residues of But zinc corrosion may be less an issue on the bad idea not only from the standpoint of physical various mysterious forms. The exact composi - outside of a carburetor than on the inside. The damage but, more importantly, from the media tion of this gum isn’t really important as long question is how these reactions can take place left behind that will eventually damage more that combative weapons are available. Early cleaners within a closed fuel system. Under ideal condi - just the fuel system. Soda blasting may be more and degreasers were based on chlorinated hy - tions, refined petroleum will not attack zinc. If viable since sodium bicarbonate is water soluble drocarbons like carbon tetrachloride, used fuel contains sufficient amounts of water or and can be washed away, but special equipment since about 1900 as a highly effective solvent. acidic compounds, reactions will occur to form is needed and the cleaning of cavities and pas - Methylene chloride (aka dichloro-methane) was corrosive byproducts. This can be accelerated sages can be difficult. Spray and ultrasonic introduced around 1940 and has been the key with other contaminants like sulfates and chlo - cleaning are other forms of mechanical clean - ingredient in carburetor cleaners until recently. rides. ing. Spray cleaning is common in large parts These chlorinated solvents pose serious health cleaning operations, which use dedicated equip - and environmental risks and have been phased Water Effects ment and an immersion tank. Spray pressures out of consumer products over the past 30 Water content in gasoline is always a hot from 20 up to several hundred psi are used, years. Carb cleaners now contain less effective topic. With the introduction of oxygenated fuels often assisted with heat. Heated ultrasonic clean - but safer solvents like acetone, toluene, and al - and ethanol blended gasoline, concerns of water ing is also an effective mechanical approach and cohol. Methylene chloride is still available and in fuel have increased. Since alcohol and water can clean difficult to remove insoluble contam - can be found if looked for. But people die every readily dissolve in each other, the ethanol added inants. Small parts ultrasonic cleaners are avail - year from its improper handling. Using a safer to gasoline will carry water along with it. An able for occasional home use but heavy use or alternative is probably a good idea. ethanol fuel mixture can have up to 0.5% water large parts require industrial grade equipment. before phase separation (at 70°F) compared to Mechanical soda blasting, spray cleaning, and Inorganic Residue in Old Fuel Bodies 0.02% for pure gasoline. But even the water in ultrasonic cleaning are all available for small Solvent-type cleaners do little or nothing pure gasoline can pose problems when the fuel parts operation but aren’t really necessary to regarding the inorganic stuff found in a carbu - is left open to the atmosphere for long periods achieve thorough cleaning of most ZAMAK fuel retor or fuel pump. Although less of a concern of time. For instance, at a temperature of 100 parts. in daily drivers, these residues are quite com - °F, pure gasoline will reach water saturation in For chemical cleaning to be successful it mon in older cars that have been idle for some 200 days. In the float bowl of an open ZAMAK needs to remove all contaminants without harm - period of time. Many of these cars’ carburetors carburetor left filled with gasoline, this assures ing the part being cleaned. Chemicals should and fuel pumps can have scale, flakes, crust or a constant supply of water (albeit at low level) also be safe to handle and easily disposed of. powder in the float or fuel bowl. Knowing the for chemical reactions with zinc to take place. Chemical cleaning using hydrocarbon solvents composition of this inorganic contamination is Since the gasoline and water starve the reaction may work for organic contaminants, but new more important in order to understand its origin of free oxygen, a protective zinc oxide layer is formulations are lacking the necessary strength and find an effective way to eradicate it. prevented and corrosive compounds will form. to do an adequate job. An alternative approach The composition of much of the inorganic The situation will be worse when ethanol is in - is the use of less hazardous degreasers, deter - residues that accumulate in a fuel body is unique volved. Contaminants in the fuel and the atmos - gents, surfactants and acidic or alkaline-based to . The main component of our car - phere will also accelerate the problem. Fuel left chemicals to attack organic and inorganic buretors and fuel pumps is zinc, alloyed with for a long period in a gas tank will go through buildup separately. The challenge is to find the aluminum, magnesium, and copper. The the same process, ensuring ideal conditions for right chemicals and an approach that will lead acronym ZAMAK is a trade name for the alloy, corrosion in zinc fuel pump bodies as well. The to acceptable results.

68 Volume 37, Number 6 • Porsche 356 Registry Zinc is more mildly etched in organic acids, the for 12 hours or more. Halfway through the extent depending on specific chemical makeup. process and again at the end, a light brushing So the choice of cleaners and degreasers for with an old toothbrush will assist in the removal ZAMAK needs to be made with special consid - of the most stubborn dirt and deposits. Soaking eration. beyond 12 hours may yield little additional re - moval but will do no harm to ZAMAK bodies. Alkali and Acid Degreasers / Cleaners Rinsing is important and a 20 minute warm Many cleaners and degreasers are com - water rinse will remove the residual degreaser. mercially available. Among these are trade - marked products like Simple Green, Greased Step 2 – Acid cleaner. The acidic nature Lightning and Pine Sol. Chemically, there is little of Pine Sol works in two ways. It will dissolve in common between these cleaners, as their for - the inorganic residue and produce a lightly ad - mulas and pH values show: hered zinc oxide surface layer. A full strength Pine Sol soak for 2 hours at room temperature Simple Green pH = 9.5 is sufficient and safe. A slow foaming will occur Cleaning a Zenith 32NDIX Carburetor 2-butoxyethonal (a solvent) during soaking as hydrogen is released from the This Zenith 32NDIX carburetor exhibits a ethoxylated alcohol (a surfactant) dissolving of inorganic residue. Soft brushing heavy buildup of varnish, deposits and staining, trisodium phosphate (TSP, a degreaser) with a tooth brush mid-cycle will help and a final and has probably been inoperable for a long sodium citrate (an acidity regulator) brushing at the end will remove reactants from while. Signs of corrosion are evident inside, the surface prior to rinsing. A 20 minute rinse with possible damage to internal cavities of the Greased Lightning pH = 12.8 should be followed by thorough drying of the zinc body. Although a chlorinated solvent would dipropylene glycol monomethyl ether (solvent) parts and passages with compressed air. probably clean the outside of ZAMAK surfaces, dodecyclobenzene sulphonic acid (a surfactant) Following these steps, a Zenith carburetor it would leave much of the internal residue be - sodium hydroxide (a base) body will look as shown below. A uniform zinc hind. A safer solvent carburetor cleaner would 2,2-aminodiethanol (a foaming agent) oxide coating will cover all surfaces, which can probably give disappointing results all around. be removed using a brass wire brush. Pine Sol pH = 2 alkylalcohol ethoxylate (a surfactant) glycolic acid (improves flow) sodium petroleum sulfonate (an emulsifier) isopropyl alcohol (a solvent) pine oil (a solvent)

Subjecting ZAMAK to these cleaners at high strengths will lead to varying results. Soaking for several hours in full strength alkaline de - greasers (like Simple Green or Greased Light - ning) will attack organic residue but won’t adequately remove inorganic contaminants. Step 3 – Zinc polishing . Polishing with A Multi-Step Cleaning Approach Using a full strength acidic cleaner (like Pine a small brass wire brush is sufficient to remove Formulations for water soluble cleaners Sol) for a long period can remove both organic the light surface oxide without scratching the and degreasers are abundant. Many secret and inorganic residue, leaving a thin zinc oxide zinc alloy, exposing bright zinc metal. These dis - recipes and patents exist for industrial and layer on the surface than can be polished bright. posable brushes are cheap and one brush prob - household chemicals with various claims. A But the low pH can lead to dangerous amounts ably won’t last longer than a single carburetor problem with these cleaners and degreasers is of zinc erosion with prolonged soaking. Clean - and top. Brushing the inside and outside of the that their usefulness for any particular type of ing should therefore be separated into two ZAMAK body leads to results like those on the cleaning is uncertain until tested, and they not phases – a long alkaline degreaser soak fol - next page. The exterior of the carburetor is created equal. The usefulness of any one lowed by a shorter acid cleaner soak. This can clean as are the inside cavities and passageways. cleaner for ZAMAK can be predicted to some ex - then be followed by a brush polishing step. The original internal corrosion in this carbure - tent by looking at its composition and pH. Acids tor left no appreciable damage behind. Threads and bases are measured on a 0-14 pH scale, Three Simple Steps can be chased, mating surfaces flattened, hard - with higher values indicating basic (or alkaline) Three simple steps to ZAMAK cleaning can ware plated, brass cleaned, jets sized, and the solutions and lower values corresponding to be done at home using readily available cleaners carburetor can be assembled and tested. acids. Water has a neutral pH that falls near 7. and no special equipment other than a few Alkaline cleaners are generally effective at de - buckets, a toothbrush, and some small brass greasing. Acidic cleaners can remove inorganic wire brushes. The steps are as follows: compounds including oxides, hydroxides and chlorides but can attack metal as well. Zinc is Step 1 – Alkali degreaser . The formu - readily etched in strong mineral acids like hy - lation for Greased Lightning is quite effective at drochloric, acetic and nitric acids, leading to the removing organic buildup, used at 50% strength erosion of metal and the creation of byproducts. at room temperature (above 65°F) and soaking Continued

www.Porsche356Registry.org • March / April 2014 69 How Bad Can it Get? But there is no miracle elixir that can prevent Above: After brushing with a brass wire brush, a suc - Left too long neglected, ZAMAK casting will damage to zinc castings. Many additives contain cessfully cleaned Zenith carburetor body - inside and corrode beyond repair. The amount of damage alcohol, which will increase the capacity of gaso - out. Left: Too long in less than optimum conditions. in the poor Zenith body below is a result of un - line for water and make matters worse. The best known exposure to the elements not from the remedy is fresh gasoline or no gasoline - and A Note about Safety outside (which is in fairly good shape) but from eliminating ethanol if possible. Although the chemicals used here are within. After alkali degreasing and a long acid common household cleaners, it should be cleaning, the removal of corrosion revealed the clear from their ingredient lists that they extent of pitting inside this potmetal body can contain some nasty stuff. Household (right). This carburetor had been out of com - cleaning products are responsible for mission for many years so the damage probably about 10% of reported toxic exposures in occurred without the help of ethanol in the fuel. the U.S. Ingredients should be considered There is a wide range of fuel additives that claim poisonous and can be harmful to the skin, to allow fuel to remain in your car for prolonged lungs, and eyes. Adequate ventilation is periods. These are various petroleum distillates necessary, as are safety glasses, gloves and and organic solvents that may help prevent the common sense. breakdown of fuel that leads to gum formation.

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