5/1/2003
Making Big Decisions About Cleaning Small Parts
By Doug Kaufman
To America’s motoring public, an internal combustion engine is more than the sum of its parts, of course. But when they are expensive or unavailable, those parts suddenly take on an increased value.
For engine rebuilders, the question of whether to reuse or replace internal engine components cannot always be answered the same way. Depending on the engine, the part and, of course, the customer, your response to the parts issue will be different than everyone else’s.
But one thing is for sure – if you’re reusing parts, you’re cleaning them first. There are as many ways to clean as there are parts themselves and rebuilders are constantly looking for the best combination of equipment and techniques to make their parts cleaning process an effective, efficient and potentially profitable part of their business.
From the simple methods employed by small custom engine rebuilders to the high volume cleaning procedures used by large production remanufacturers, cleaning parts can be a complex story.
"When it comes to cleaning internal engine small parts, I’m probably one of the industry’s dinosaurs," says Dave Deegan, Engine Lab of Tampa, Tampa, FL. "I believe that the hand is often better than the machine. Of course, you also have to have somebody who is willing to look carefully at the part and clean it properly."
Depending on the part, cleaning at Deegan’s shop may be labor intensive or fairly automated, but a member of his crew is always involved in the inspection and cleaning process. It’s a system that, despite its emphasis on human interaction, is very efficient and serves Engine Lab of Tampa’s needs well.
"Take the valve train, for example," says Deegan. "We’ll chemically clean the parts first in order to get as much grease and crud off them. We’ll use commercially available baskets in our jet sprayer, but we also make our own parts baskets as needed."
Following the spray wash, Deegan’s crew inspects the components for further cleaning as required. "Valve faces are cleaned with a glass bead machine. Springs, rocker arms and nuts and bolts are cleaned with a light tumble in our ceramic media," he explains.
Rocker arm shafts are often tumbled as well, says Deegan, but shafts in 3.3L or 3.9L Chrysler engines are typically put into a small lathe and cleaned with an abrasive pad. "Roller lifters and lash adjusters are chemically cleaned and then touched up by hand as needed," says Deegan.
"We don’t normally clean and reuse pistons or flat tappet camshafts," says Deegan. "In our process, we always try to replace those parts with new unless it’s a unique style. If we do end up reusing existing pistons we’ll clean them chemically and then put them into an ultrasonic cleaner to decarbonize them."
Ultrasonic cleaning is based on a phenomenon called "cavitation" which occurs when high frequency sound waves are introduced into a liquid cleaning solution. This produces countless "microbubbles" or cavities which violently implode against the part to be cleaned. Manufacturers of ultrasonic equipment say the resulting implosion can produce pressures as high as 10,000 psi, and produce an effective "scrubbing" effect.
Deegan’s claims to being a dinosaur aside, he actually has very progressive thinking about cleaning. Not only does he recognize its value to his business, he is willing to invest in the newest equipment.
"My next shop equipment purchase will probably be a soda blaster," Deegan says. "From what I’ve seen, the process seems to be great because the media completely washes out – there’s no retention issues to deal with."
Soda blasting can effectively remove corrosion, grease, paint and coatings from a variety of metals and composites, so it’s appropriate for cleaning many different parts, according to manufacturers. The non-toxic water soluble medium can be easily be washed away and disposed of.
THE TRIED AND TRUE
According to Scott Murray, the preferred cleaning method at Murray’s Auto Parts in Lancaster, OH, is a dependable old three-step thermal cleaning system that bakes, blasts and shakes the parts clean. "Anything I can run through the oven I will," says Murray. "It’s especially good for very old parts. Right now we’re doing a 1958 Chevy 283 engine. Although we’re replacing a lot of the parts on that motor, we sent the bellhousing through the blaster."
Murray says he also has a jet spray washer that does just as good a job as the thermal system for cleaning, but he feels the oven provides a better final finish important to restoration customers. "When we use it, the oven pulls all of the oil and grease out of the parts so they’ll paint much better. It’s fantastic for restoration work."
Murray relies on the jet spray washer to clean parts he won’t put into the thermal system. "I don’t like to run anything with a baffle in the blaster because the beads can get caught."
A new twist on the jet spray concept combines the cleaning power of a heated water-based detergent with a concentrated spray nozzle. Up to a 400 psi stream of water can be directed to wherever it is needed.
Murray uses a small parts tumbler for cleaning very small parts, although he tries to talk customers into buying new parts. "For example, we check every valve spring for tension and try to sell replacements if they’re below spec. Because an overheated engine will show up in the valve springs, we don’t reuse many springs."
Murray says sometimes parts for his engines are cost prohibitive to replace, so cleaning is a necessary part of the rebuilding process.
BIG SHOPS, BIG PROCEDURES
Jasper Engines and Transmission in Jasper, IN, builds more than 65,000 gasoline engines a year. According to Brett Mehringer, each of these remanufactured engines gets all new valves, valve springs and pistons. All chain-driven gears are replaced as are all pan bolts, timing cover bolts and many head bolts (all torque-to-yield bolts are replaced, as well as all Chevrolet head bolts: "It’s cheaper to replace them than to clean them!").
However, Jasper reuses many parts, according to Mehringer, with four different cleaning processes used depending on the part.
"Our first and most-used process is a Kolene salt bath (at a temperature of 730° F) and shot blasting procedure," says Mehringer. "We clean approximately 75 percent of our parts with this process, including rocker arms, headbolts, trim bolts, thrust plates – any part that will not allow shot to wedge into crevices or tight corners.
"Our second process uses a hot tank and tumble procedure. This is used for rocker arm shafts, mechanical rockers or other parts that would allow shot to be wedged into areas," he explains.
"Our third process again uses a hot tank but parts are sandblasted," Mehringer says. "This is used for oil filter adaptors and timing covers with oil pumps. We use coal slag in our blaster for these parts."
The fourth process used by Jasper is a hot tank and sodablast combination. "This procedure is used for cam carriers, intakes, etc.," says Mehringer.
At Jasper, valve lifters are cleaned and rebuilt in house, or sent out to be rebuilt.
Like Jasper, Recon Automotive Remanufacturers, Philadelphia, PA, puts a heavy emphasis on determining which parts can be reused and cleaning them accordingly. John Lukavsky, Recon’s plant engineer explains that the decision to clean and reuse, or start with new components, requires careful analysis. "Can we reuse the components that have not experienced high levels of wear? And will it be economical to do so?"
Lukavsky says the parts most often cleaned and reused in his facility include rockers, valves, springs and bolts. "Each is really cleaned the same way, since we’re really just talking about cleaning metal parts. We remove the debris from the metal using a shotblaster. This takes us down to bare metal, after which the parts are put into a parts washer. They’re cleaned and all of the dust and debris is removed."
The next step, according to Lukavsky (and echoed by each subject in this article), is critical to success. "We sort the parts using both visual and quantitative inspections. We measure them to determine if they fall within our tolerance to remanufacture an engine. This is also the perfect time to check for surface defects because they’re easy to see after the blasting process."
Lukavsky explains that Recon uses nearly 15 people in its parts cleaning process. "Yes, it’s labor intensive, but we find that in many cases it’s much cheaper to clean and reuse the parts than to buy all new parts."
Recon manufactures a line of "Bulletproof" engines as well as high-performance marine and race car engines, all of which are remanufactured using new components. But Lukavsky says for the typical engine, unless a customer has a need or specifically requests new parts, properly cleaned and checked used parts are installed.
"We have a very stringent quality inspection in-house. Parts are inspected beginning at teardown and then again at many individual steps along the way. We are confident in their quality," says Lukavsky.
"Just because a part is reused, it’s still made out of the original material. We’ve confirmed that it is dimensionally correct. As long as it performs as the original, it will be cheaper for the customer," he says.
The key to a successful parts cleaning process, agree all of these professional rebuilders is a two-step approach that includes both a proper, efficient cleaning method and careful parts inspections.
COMPONENT PARTS CLEANING TIPS
These tips have been assembled from discussions with rebuilders and parts equipment manufacturers. Keep in mind that other forms of cleaning may be just as viable depending on the quantity, materials and equipment employed.
- Pistons - Disassemble and remove rings. The piston may be initially cleaned in an aluminum-safe spray washer or soak tank. The second process will be to glass bead the piston top only.
Piston cleaning is usually not done as labor costs are usually too high and potential part failure rates too high. Blocks usually have wear areas and require reboring anyway. Many rebuilders say unless they are unique or extremely difficult to replace, pistons are usually replaced with new in their engines, although those that are reused are soaked in a hot detergent vat, rinsed with water and the tops carefully and gently wire wheel buffed.
Another method of cleaning pistons (as well as other parts that follow) is with soda blasting. Baking soda, often with various "enhancements" added to increase flowability or moisture protection, is effectively abrasive yet can be easily disposed of.
- Intake valves - soaked in hot caustic and wire wheel buffed; stems are polished with a 600-grit belt and inspected for burrs, etc. Valves also can be cleaned in a media tumbler with a solvent where stem protectors are used on the valve ends. Valves can then be glass beaded for cosmetics.
- Non-hydraulic lifters - hot caustic soak.
- Hydraulic lifters are hand washed with spray carb cleaner.
- Steel rocker springs - soaked in a hot caustic vat.
- Crankshafts can be soaked in hot caustic vat, later they can be wire wheel buffed or bead blasted. Heat cleaning is another option.
- Camshafts can be cleaned the same as cranks with the exception of the bead blasting process.
- Rockers - may be cleaned in steel media tumbler for 10-15 minutes or may be cleaned in a spray washer or soak tank. (Many shops recommend that aluminum rockers should be soaked in a non-caustic hot detergent vat).
- Valve springs - cleaned in a media tumbler with solvent or spray wash or soak tank.
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