Click on a thumbnail to see the full-size image
Engine Cleaning Options In a Water World
When it comes to selecting aqueous cleaning equipment there are a multitude of questions posed to engine builders. What kind of solution should you use? Should you buy a hot tank or a jet washer or both?
By Brendan Baker
Aqueous cleaning equipment has gained a solid foothold in today’s machine shops, no doubt, and the momentum appears to be continuing for the foreseeable future. Aqueous systems come in all shapes and sizes and some experts believe they have more or less replaced solvent-based systems that produce ozone-hating volatile organic compounds (VOCs).
There are basically four types of aqueous cleaning systems that engine builders use:
The first type of cleaning system is a manual system. It is, in essence, a sink on a drum that recirculates a heated water-based solution. A filtered stream of 100°-115° F aqueous cleaning solution flushes away dirt and oil as parts are cleaned with the familiar brush on the end of a hose.
"Many of these drum and sink tanks are also being converted to bio-remediation tanks," says Perry Crabb, AXE Equipment, Council Grove, KS. A bio-remediation system is a water-based solution that contains microbes, which are live organisms that eat oil. You may have heard of microbes before when Exxon used oil-eating microbes to clean up the 1989 Valdez oil spill on the Alaskan shores of Prince William Sound.
The second type of system is an immersion system. "You’re immersing the part in a cleaning solution," explains Butch Boselli, Graymills, Chicago, IL. "Within the immersion cleaner’s tank there’s a lift platform that agitates up and down during the cleaning process. You can also use this type of system as a soak tank.
"In addition to a lift platform, if you want to add more turbulence to the tank you can add a recirculating pump. The pump moves the cleaning solution around in a circle inside the tank, creating more of a scrubbing action," Boselli notes.
"An engine block cleans very well with an immersion washer because regardless of the intricacies of its design – blind holes, channels, etc. – the cleaning solution gets into all those areas and cleans them," says Boselli. "By the agitation process of going up and down, it’s forcing the cleaning solution into all the tight areas of the engine part. As it goes down, it forces the solution in; as it goes up it sucks the solution out."
The third type of aqueous system is the jet washer or cabinet washer, which is essentially an industrial-strength dishwasher. Jet washers use a pattern of spray nozzles that spray cleaning solution with detergents under some pressure (typically 40-60 psi) onto the parts.
"There are two elements that clean the part: you have impingement (pressure) of the spray, like cleaning your sidewalk with a garden hose, and then there is the chemical itself that cleans," says Boselli.
The disadvantage of the spray cabinet washer is actually the advantage of the immersion washer," says Boselli. "The jet washer has a set spray pattern – any place that the spray hits it cleans very well. But you can’t get into tight areas – blind holes, for example. And if it can’t get in there, it can’t clean."
There are different types of spray cabinets also. Front loading cabinet washers are the most common type. Typically these have spray bars underneath the basket, on top of the basket and on the sides, so you get full coverage of the spray. Another type of cabinet washer is the top-loading kind. The advantage to this design is that you can use an overhead crane to load it.
High-pressure spray cabinets require manual operation and clean areas that are difficult to clean. "A lot of people think this is a bead blaster, but it’s actually an aqueous high pressure sprayer," notes Boselli. "A spray nozzle blasts out about 400-600 psi of pressure, so you can clean blind, tight areas with a high degree of impingement with an aqueous cleaning solution."
Give Me Ultrasonic
The last type of aqueous cleaning system is the ultrasonic washer, used primarily for removing carbon and burned on oils. Ultrasonic cleaning represents the high end of the aqueous cleaning scale. However, though this equipment can be more expensive than other washers, they’re not out of reach, cost-wise, for most shops.
Ultrasonic machines are completely aqueous-based. And the only thing to be concerned about as far as disposal goes is what the engine builder puts into the ultrasonic tank. "You’re adding carbon and heavy metals to the tank," says Windy Adams, Global Sonics, Danville, IN. "In most cases what you end up with isn’t a hazardous waste but it still has to be tested and disposed of properly. We use 90 percent water and 10 percent detergent. The detergent works on aluminum and any other type of metal. The nice thing is, the detergent has brighteners so when the part comes out it looks like new."
Adams estimates that ultrasonic machines eliminate about 95 percent of the labor involved with cleaning. In some cases, he says, you may have to hand brush some stubborn areas. Often, however, the ultrasonic tank has loosened the dirt and it just brushes off easily.
"Ultrasonic cleaning does several things," explains Adams. "First, it eliminates VOCs. Then, in some cases, it eliminates or reduces the need to bead blast. The other plus is it reduces 95 percent of your labor to clean parts. Let’s say you were cleaning two aluminum cylinder heads. After the heads have been pre-washed in a jet washer, the time you spend in a solvent tank and a bead blaster, you could put them in the ultrasonic tank and in 20-40 minutes those two cylinder heads are going to be clean and ready to rebuild. It may take the same amount of time to clean the cylinder heads manually, but with the ultrasonic machine you’re not standing there doing it. You can be doing other work while the machine is doing the work for you."
With new style engines and their overhead cams and valves, there are a lot of blind holes and areas hard to reach with any other type of equipment. Ultrasonic, because it works on sound waves, can reach into all of those areas.
If you do use a bead blaster, you can use the ultrasonic washer to get all of the media out. It can reach the smallest passages and clean them out. Also, ultrasonic washers work very well on cleaning small parts. "Just put all your small parts in a basket, turn it on and walk away," says Adams.
Cleaning On A Budget
Smaller engine builders will usually start with either a jet washer or a hot tank. These can, in fact, be combined into one unit, according to Ed Gruel, Western Equipment, Bothell, WA.
"What we normally do with budget conscious shops is start them out on a jet washer with an aluminum-safe cleaner and a hot tank set up with a cast iron cleaner. So you have one machine that will do aluminum and another that will do cast iron," Gruel explains.
"The difference is, if you use an aluminum-safe chemical, it will not take off paint. On the other hand, if you use a cast iron cleaner to remove paint, it is too strong to use on aluminum, and if you put an aluminum piece in the chemical solution it will actually begin to dissolve it," says Gruel. "Besides, it makes a big mess too!"
Gruel points out that as a shop grows it will ideally add another jet washer to clean cast iron. "You can’t switch chemicals back and forth in one washer because it’ll cost too much and you’ll waste too much solution. You have to use one or the other," he says.
When It Foams It Makes A Mess!
Graymills’ Boselli reminds rebuilders to not only use different chemicals for the various metals (cast iron, aluminum), but also use different chemicals for the various cleaning systems (spray cabinets, hot tanks). "With a spray cabinet system, you have to make sure the solution won’t foam. For instance, have you ever made the mistake of putting standard hand soap into your dishwasher? If you have, you know it foams all over the place," says Boselli. "So when you talk about dishwasher detergent or spray cabinet solution, they have low foaming properties."
LS Industries, Wichita, KS, which designs and manufacturers all types of metal cleaning equipment for automotive and industrial industries, works with a detergent company to custom blend chemicals for customers who may have special needs or water that may not be compatible with off the shelf soaps.
"Some soaps are going to foam more with different types of water – different hardness and softness," says Michael Wigart, LS Industries. "If a customer is having trouble, we’ll ask for a sample of their water and have it analyzed and try to put something together that takes care of the foaming and leaves a minimum of water spots on the product."
Wigart says that most soap manufacturers, in fact, do offer some custom soap blending services. You should check with your soap manufacturer to see what services are available. At the minimum, manufacturers will be able to consult with you on the best choices for your particular situation.
According to AXE’s Crabb, with good temperature, clean detergent solution and a good pumping system, you’ll clean very well. But if you’re missing one of those three ingredients you won’t get anywhere.
"Right now there is no way to electronically monitor the cleaning solution’s PH level, so you’ll still have to periodically check it by hand. What the washers tend to do if they’re undercharged is foam," says Crabb. "It will foam, too, if the temperature is too low. Foaming is a tell-tale sign of one of these problems."
Another thing that will produce unwanted foam in your aqueous system is animal fat: "One time, we had a customer complain that his machine was foaming. We discovered he had bought some muffin pans at an auction from a restaurant which he used to wash loose bolts and small parts in the jet washer. The pans had been coated in animal fats which was then introduced to the cleaning solution.
"It just killed the chemical," says Crabb. "Once a fat gets in there, you cannot use defoamers. You have to drain all the solution and start over. There isn’t anything that will counteract it."
Skimmers And Other Oil Removers
You can add filters to just about any aqueous cleaning machine. The filters separate the particles but won’t take out oil (or, if so, only a small amount). To get rid of the oil you either have to use an oil skimmer or a coalescer. Oil skimmers work only when the machine is not operating. A coalescer, however, is a different type of system.
"A coalescer is an oil/water separator. The difference with this system is that a coalescer can be used while the machine is in use. You can be removing the oil from the cleaning solution all day long," says Graymills’ Boselli. "It’s a very effective way to maintain your chemical solution."
The benefit of both of these types of skimming systems is that they keep your solution cleaner for a longer period of time. You won’t have to clean the solution as often and you’ll get more consistent cleaning.
"It’s the same as when you’re washing dishes at home in the sink: when you first start out, everything comes out nice and clean," Boselli explains. "By the time you get to the bottom of the dish pile more grease is in the detergent and it’s not as effective."
Gotta Have The Heat
The key thing to remember about cleaning in aqueous washers is that you have to have good heat in order to effectively clean the parts," says AXE’s Crabb. "Your spray cabinet ideally needs to run at about 170°-180° F. If you’re running at 140° F, you’re wasting a bunch of electricity to heat the solution and not getting the results you want. It’ll clean at 140° F but not nearly as well as it would at 170°-180° F. We discovered that many people didn’t know what temperature their solution was."
But, too hot is no good either. "Higher cleaning temperatures evaporate water faster," says Crabb. "If too much water evaporates you’ll expose the burner tube to air and it will heat up quickly and may burn the heater out."
Today, some equipment manufacturers have countered this problem by adding digital thermal controllers to the front control panels to monitor water temperature and water level. "Since we started offering the thermal controllers, I never have to replace heaters anymore because I don’t have to – they’re not burning out from operator error," says Crabb.
Cleaning is one of an engine builder’s most important concerns. If you use shot blast ovens to clean or you hone a block, you will need to use an aqueous system to clean all the grease and particles from the machining process and the shot from the engine. Thermal cleaning has its place, but you’ll still have to have some sort of aqueous cleaning system.
In fact, according to some cleaning system manufacturers, no matter what type of cleaning equipment you use, aqueous based systems can be an important complement to any cleaning process.
For more information on working with your jet washer, see "Don’t Machine Until You’re Sure It’s Clean" (Dave Monyhan’s Machine Maintenance column), August Engine Builder, page 22.
Where To Get Aqueous Cleaning Equipment:
Ace Automotive Machine Sales
Andersen Metal Products
Landa Water Cleaning Systems
Orison Marketing LLC
Peterson Machine Tool
Blu Surf Inc.
RMC Engine Rebuilding Equipment
Disa Goff Inc.
Sunnen Products Company
Viking Blast & Wash System
Winona Van Norman (LS Industries)