Two new engine cleaners are thoroughly tested
Much of my readers’ mail asks about engine cleaning. Now I can finally put that topic to rest. Tests with two new products have shown that either can quickly get rid of the most stubborn muck, grime, and baked-on “varnish” that model engines acquire. One of them is the newly reformulated Demon-Clean (DC).
DC is now available from BJ’s Model Engine Service (51 Hillside Dr., Beacon Falls, CT 06403; E-mail: [email protected]). The new DC works as well as the original (which I tested a few years ago and reported here on the excellent job it did) but has a much longer shelf life.
The other product, brought to my attention by Stan Grett (Enterprise, AL), can be found at most supermarkets. It’s Dawn Power Dissolver (PD), and it comes in a plastic spray bottle.
Products tested
- Demon-Clean (DC): mayonnaise-like consistency; supplied with a small, stiff-bristled brush for application. The reformulated DC has less pungent vapors than the original and a longer shelf life.
- Dawn Power Dissolver (PD): less viscous; spray penetrates well between cylinder fins yet is gel-like enough to be nondripping. Comes in a spray bottle with a narrow, easily aimed stream.
Both products carry strict cautionary warnings. Wear rubber gloves (they are strong skin irritants) and safety glasses (to avoid eye contact). I did the engine-cleaning work outdoors as DC recommends; PD can be used safely indoors and has a mild, pleasant aroma.
Test procedure
To test the two cleaners I obtained from a friend a couple of grungy CL engines that had probably never been cleaned. They had been put away dirty and sludgy and left like that for more than 35 years.
Rather than apply DC to one engine and PD to the other, I made a side-by-side comparison: I applied DC to one side of each engine (including half the head fins) and sprayed PD on the other side. I laid both engines on their sides on a strip of aluminum foil to avoid contamination of my work surface.
After roughly an hour I used warm water and a stiff-bristled toothbrush to rinse the engines clean over the kitchen sink, again wearing rubber gloves and safety glasses.
Results and observations
- DC seemed slightly more aggressive than PD, but both products worked exceedingly well. Each removed all surface sludge with one application.
- Deeper incrustations (e.g., between head fins and in the cavity around the plug) required a second application, brush, and rinse.
- A thick streak of orange enamel on one case came off completely after the second cleaner–brush–rinse cycle.
- PD did an excellent job on burned-on oil residue on a four-stroke muffler (RCV91-CD). The residue wiped right off after spraying PD and letting it sit an hour. I did not remove the muffler for that test; the PD sprayer is easy to aim.
- I performed no disassembly for any of these tests.
What about water getting inside? Not to worry. Some years ago, when testing for corrosive effects, I found that brief exposure to water—followed by thorough drying and a light oiling of moving parts—produced no harm. As a precaution, dry the engines completely after rinsing and apply a little after-run oil to protect internal surfaces.
The new O.S. LA Series of engines
The new O.S. LA Series is instantly recognizable by its "midnight blue" exterior finish. Made with O.S.'s usual precision and attention to detail, these power plants are available in both RC and CL (called LA-S) versions and in a wide range of sizes, from .10 through .65. All are reasonably priced.
I obtained two of the smallest LA engines—the .10 and .15—and a .25 LA-S.
Manuals and beginner support
The well-illustrated instruction booklets that accompanied these power plants state that they were "developed to meet the requirements of beginners and sport flyers." The manuals seem ideal for that purpose:
- They list all required accessories, even down to the fuel can and battery leads.
- They describe and illustrate glow plug, propeller, and muffler installation, and even how to fill the fuel tank.
- Needle-valve adjustment is thoroughly explained; an entire page is devoted to it.
- Troubleshooting is covered in detail on two full pages, plus a flowchart diagram that covers every stage of carburetor adjustment.
- Exploded drawings show every component and part number.
These details may be elementary to experienced modelers, but they are invaluable to beginners. The only problem is getting new engine owners to read and follow the instructions. Even for experienced flyers, it’s always best to read the instructions all the way through first.
Carburetor, needle, and other details
- The LA engines use simple, adjustable air-bleed carburetors that permit the needle valve to be moved to the rear, allowing safe adjustment at a distance from the propeller.
- O.S. needles include a precision hole in the outer end for adding a wire extension and a setscrew for gripping the wire—an especially thoughtful feature.
- Hardened steel washers are fitted between the propeller driver and the case front to prevent galling and wear from rearward pressure during electric starting.
- The propeller driver is a positive-drive design, eliminating any chance of slippage between the crankshaft and the driver.
When I first turned them over, the three LAs felt smooth and snappy right out of the box. The manuals confirm that very little break-in is required.
Break-in procedure
The booklets instruct a simple break-in that can be done in the airplane:
- Run out one full tank of fuel on the ground with the needle set roughly half a turn rich.
- After each flight, reduce the richness a trifle.
- By the sixth flight, the LA should be nicely broken in.
Accessories and mounts
O.S. offers useful accessories for the LA engines, such as spinner nuts for easy electric starting. Beginners will likely appreciate O.S.'s predrilled and pre-tapped radial motor mounts, made from aluminum to help cool the engines.
- The O.S. radial mounts cost more than molded plastic types but eliminate the need for close-tolerance drilling and tapping.
- They come ready to use with the proper-size mounting screws.
- Unlike many molded radial mounts, their mounting surfaces are flat and parallel.
Transcribed from original scans by AI. Minor OCR errors may remain.
