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Although extremely important, the job of cleaning engine parts leaves nothing to the imagination. You’re idly standing with a spray gun in your hand or beside a washer tank or cabinet. It’s a basic, time-consuming procedure, but that grime, oil and baked-on sludge won’t come off by itself.

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This necessary evil is the difference between a satisfied customer and a comeback that’ll cost your shop’s bottom line. Whether before basic repair or restoration, cleaning the engine components makes the remanufacture a less cumbersome experience further in the process.


As with many kitchen appliances, engine cleaning is no different: There’s more than one way to clean a fish, so to speak. Several cleaning options are available and some shops incorporate a combination of methods that provide a number of advantages.


One tried and true procedure, aqueous spray cleaning, wins over most shops because it has proved to be more environmentally sound than the toxic volatile organic compound (VOC) solvent cleaning ways of the past that polluted the air as well as endangered workers. According to the U.S. Environmental Protection Agency (EPA), aqueous cleaners contain less than five percent (50 grams per liter) of VOCs.


Many washers apply a heated stream flow – primarily in the mid-high range of 100 degrees F – with the help of detergents and surfactants. 


Ideal for cleaning less-sizable instruments or baskets of multiple parts, aqueous solution-based systems suit most of an engine shops’ needs. In addition, jet spray washers bring the element of automation, freeing up your employees to concentrate on other tasks. Jet sprayers work akin to a stronger version of a dishwasher. Fixed nozzles apply the water solution as the soiled component rotates to completion. 


Though your once-soiled part – after a run through the spray washer or other aqueous devices – has the vast majority of sludge removed from its surface, chances are your elbow grease will have to rid the remaining part of oil and dirt trapped in the hard-to-reach areas such as oil galleys and water jackets. 


For shops wanting less hand cleaning afterward, there’s the ultrasonic tank cleaner. While the jet spray washer is similar to an industrial dishwasher, the ultrasonic tank may remind one of a deep grease fryer. Instead of breaded chicken or potato wedges, the more oblong parts–such as a cylinder head– are submersed in water through extreme levels of vacuum and pressure via the vibration of sound waves. Depending on the equipment, the frequency can range from 40 to 170 Kilohertz.


The process, known as cavitation, creates a series of bubbles that dismantles the pressure. The vibration literally breaks the water out of its molecules under the solution at approximately 150 degrees F and decays the dirt and grime off of the engine component in usually less than an hour’s time. 


The advantage to ultrasonic cleaning is that it cleans internally – ideal for pistons and cylinder heads – minimizing the use of manual cleaning thus maximizing your worker’s productivity. In addition, it’s environmentally safe and meets EPA standards. 


Comparable to a self-cleaning oven, blast ovens are – of course – more industrial-sized and have been a staple in engines shops for many decades. Like ultrasonic tanks, blast ovens also lessen the need for hand cleaning dirty parts.


The major advantage is the lack of cleaning solutions. Most ovens operate in temperatures of at least 500 degree F. In the course of a few hours, the heat erases the stained containments from the part. Afterward, it is either sprayed off or run through a steel shot blaster to remove any remaining residue, rust or paint to produce a like-new look.


One disadvantage to thermal ovens is that the temperature is too high to handle aluminum. At temps above 500 degrees F, the aluminum can become annealed and lose strength. Experts say you must exercise extreme caution when using an oven for these components. 


Though these methods have been performed in shops time after time with good results, newer approaches have proved just as, if not more than, effective. As the age of cast-iron components moves into the world of more aluminum-based parts, end users have found that the original methods can be too harsh for the today’s metals. 


Some users feel the blast ovens involve unnecessary steps and are too intense for aluminum. Plus, blast ovens are generally serviceable for heavier steels and bulkier parts in a world where automotive accessories are becoming increasing compact.


Other shops have shied away from thermal ovens and spray washers that utilize cast iron cleaning solutions due to its hasher cleaning process. With some spray washing solutions, the finish of an aluminum part will take upon a tarnished look rather than a like-new appearance due to the chemical makeup of the cleaning solution that was put through the part.


Additionally, some shops will add another step to the process by painting the aluminum to make it look new, thus taking away productive time that could be utilized elsewhere. To combat these issues, soda blasting has offered an applicable alternative to traditional engine cleaning.


“It all depends on what your definition of ‘clean’ is,” says Delia Downes, product manager of ARMEX baking soda-based media manufactured by Church & Dwight Co., Inc. 


Soda media is a form of baking soda that has been developed for industrial use to remove hardened, baked contaminants such as oils and grease. It is delivered in a compressed air stream or a slurry blast system. 


Simply put, it’s the transfer of kinetic energy. The crystals of the soda break upon the surface of the part thus lifting the caked dirt and oil off of the automotive part. As a result, the part is restored to a like-new surface finish. 


“It is line of sight operation,” Downes  explains, “so you have to direct the nozzle spray toward the contamination to be removed. It is a manual process but it can be automated if there is a large throughput  of parts with the same geometry and dimension being cleaned.”


Sodablasting is one of the more effective methods to achieve a detailed level of clean. Much of the work can be done in one step, eliminating the various chemistries used in multi-step processes.


“The other benefit – and this is key – is that it’s water soluble,” says Downes. “Other media popular in this industry, like plastic and glass, can cause particle ingression issues, becoming trapped in passageways and then causing engine failure or warranty issues.”


Baking soda-based media is not toxic or combustible and is on the low end of the Moh’s hardness scale. Considering soda blasting as a cleaning method can be very cost effective depending on the required level of clean, the number of steps eliminated and the associated cost of the use and disposal of chemistries used in those steps. Some shop owners also have implemented soda-blasting cabinets as a cost-effective method versus ultrasonic tanks.


“Before we started soda blasting, the biggest thing was that people didn’t see the need to clean parts thoroughly enough,” says Herb Tobben, Lab Manager at Clemco Industries. “This was destroying parts of their engine because the media would act like a grinding compound in the engine and get into the oil passageways. They didn’t understand the importance of a thorough wash.”


Clemco designs its soda blast cabinet, The Bicarbonator, which cleans and strips automotive parts. The device – visually akin to an incubator – allows the user to blast the part of its debris. Most of their cabinets use media that is water soluble, thus keeping media and grease from staying in internal passageways.


“That’s where a lot of people get into trouble. Years ago, people would try to do a good job of degreasing and then blasting,” Tobben says. “Then after that going through a parts washer to get the blast media out because otherwise, the bearings and the engine would get destroyed. All too often, they try to do it in high production, something goes wrong and it gets in the engine and eventually destroys it.”


Soda blasting has been known as a fairly new method, but its popularity is tied into its Catch-22 scenario. Though it enjoys many advantages, baking soda can be utilized one time per cleaning and is not recyclable. But it effectively rids parts of grime in the venue of a closed loop process, thus saving time in the shop’s workflow. 


First used exclusively for aviation parts, soda media has been making an impact in the engine overhaul market.


“In the last five years, this method is finding its niche with engine builders and gaining acceptance,” says Downes. “As the transportation industry innovates to develop energy efficient components, and uses lighter materials the associated cleaning methods must adapt.  ARMEX soda blasting is an excellent choice when preserving surface material is the paramount concern.  With it you have no changes to base material, machined tolerances, screw threads and other complicated contours.”


Shops have to change their cleaning process or else they’ll damage the parts. Products where preservation is paramount when the end user wants no change on the surface material, means you want no change to machine tolerances, threads, screws and folds.


“If you’re cleaning as part of a disassembly, reassembly that’s one thing,” Downes says.  “But many of our customers are selling refurbished blocks and heads and want to offer something that looks brand new.”


As shop managers and owners look for the next, best method of cleaning engines, they’ll always rely on what has been working best for decades. Whether it’s one method or a combination, ultimately, every shop is different but your customer’s satisfaction and demands are consistent. 

For more information about cleaning equipment and solutions, be sure to look through the Buyers Guide section on cleaning included in the following pages of this issue  or go online to read it on our website at:

wet blasting is also known as slurry blasting, liquid honing and vapor blasting. a wet blast system uses water with abrasive to form slurry that is used for the blast effect. the velocity of the slurry along with the physical characteristics of the blast media is what does the cleaning or peening. ultrasonic systems come in many sizes, though many look like the size of a food fryer with a heated tank on top and the valves and nozzles below.ultrasonic cleaning systems utilize sound waves that vibrate the solution at high frequencies, producing tiny bubbles that scrub the part clean.Soda blasting can be done either wet or dry and produces a finish similar to other blasting media except that soda is water soluable and will not get stuck in tiny oil and water passageways.

Engine Builder Magazine