Life is tough on anything made of metal that lives outdoors. Rust is a constant threat. But beyond that, there’s a form of cannibalism that takes place when different types of metals come into direct physical contact with each other. Dry contact between dissimilar metals is no problem, but when an electrolyte (water in the form of rain, fog, dew, etc.,) is introduced, it starts an electrochemical reaction that results in one of the two metals being devoured.
Metals are categorized by a characteristic known as nobility or resistance to corrosion. On the scale of nobility, platinum is at the top, and magnesium is at the bottom. The metals in between are all the rest. The closer to the top of the scale, the less vulnerable to corrosion the metal is. On the typical motorhome, the metals used are mild steel, stainless steel and aluminum. On the nobility scale, stainless steel is more noble than mild steel, which is also more so than aluminum. So if these metals are in contact with each other in the presence of water, corrosion will result. In some cases, incompatible nuts and bolts become virtually welded at the threads and must be destroyed in order to remove them. Stainless steel screws used to attach aluminum components can cause destructive corrosion problems.
Traveling and camping near the ocean accelerates the problem, speeding the corrosion process significantly because of the salt in the environment. Likewise, driving where there is residual salt on the road (used in the winter in some regions to melt ice) can cause rapid corrosion.
So, what can you do to protect your motorhome and dinghy vehicle? Fortunately, you don’t have to change all the hardware to ensure metal compatibility, because there are some good products on the market that can keep corrosion from taking over.
Look in the Medicine Cabinet
On the low-tech side of things, coating the contact interface between metals with petroleum jelly (a common brand is Vaseline) provides some inexpensive protection. The objective is to exclude water from the area where metals contact each other, and petroleum jelly does a pretty good job if it’s smeared on evenly and thoroughly. Petroleum jelly is inexpensive and available almost everywhere, plus it has multiple uses in the family first-aid kit.
Boaters have to deal with ongoing corrosion problems, so it should be no surprise that one of the best solutions to fighting corrosion can be located by ducking into a marine supply store such as West Marine. LanoCote, made by Forespar, is available in either a paste form in a 4- or 16-ounce jar, or in an 8-ounce spray bottle. (MSRP: $9.55 per 4-ounce; $27.85 per 16-ounce jar; $10.75 for the spray bottle).
LanoCote combats corrosion where dissimilar metals are fastened together, such as when aluminum and stainless steel components are mated to each other, and the product is especially useful in preventing thread seizure due to corrosion. The spray version is handy for treating electrical contacts to prevent corrosion. This can also be a useful product around the house – especially for those who live in or near coastal communities.
Tef-Gel is manufactured by Ultra Safety Systems and sold through a network of dealers you can find on the company’s website. It’s at the opposite end of the price scale from Vaseline, costing $22.95 for 2-ounce jar. But a tiny bit goes a long way and one purchase, if used wisely, might last the life of your motorhome.
The way Tef-Gel eliminates corrosion is by acting as a barrier between the metal surfaces and preventing water from getting into the space separating the metals. Tef-Gel paste contains 40 percent PTFE (Teflon) powder and no volatile solvents, no silicones or petroleum solvents, so it won’t evaporate. When mating surfaces are coated with Tef-Gel there are no voids for water to be drawn in by capillary action.
An example of the use of Tef-Gel would be on the threads of a bolt and nut. In addition to serving as a water barrier, the product works as a friction barrier that reduces thread seizing, galling and friction welding. A thin coat of the material can be applied with a small brush to the interfacing metal surfaces, and excess gel cleaned away with mineral spirits or WD-40.
Lest we cause any confusion, there is another product called Tuff-Gel, made by the same company as Tef-Gel. Some use it for its corrosion-resistant properties in the same way as the product Loctite would be used on threads. It seals fast, resists oils, solvents and vibration loosening, and prevents galling.
All of the above products function as anti-seize compounds, but one of the names long recognized in this category is Loctite, and its products are distinguished from each other by color. These products are also known as thread lockers.
Let’s start with Green #290. This compound is formulated to prevent vibration loosening of small fasteners, and can also be used on electrical connectors and set screws. The liquid is relatively thin, so it “wicks” into the threads for sealing purposes. It’s best for small fasteners that might need to be removed and retightened frequently, without requiring reapplication of the thread sealer. It doesn’t require a lot of torque to break the seal, which is why it’s good on small fasteners that can’t survive a lot of twisting for removal.
Blue #242 is for use on larger threaded fasteners to prevent loosening due to vibration, and is ideal for nuts and bolts that are typically disassembled with hand tools. Blue Loctite prevents threads from rusting and allowing water penetration along the threads. This compound functions well in a temperature range from minus 65 to more than 300 degrees Fahrenheit.
Red #271 is made for high-temperature, high-strength, heavy-duty applications. It’s ideal for use on large fasteners ranging in size from 3/8- to 1-inch in diameter, and can be used to lock studs in place. It is very effective at preventing the loosening of nuts and bolts. In fact, it holds so well that when it comes time to take things apart, Red Loctite might require the use of heat combined with a hefty amount of torque applied to your hand tools.
In Star brite’s catalog of specialty items, you’ll find Anti-Seize Thread Lubricant available in a 1-ounce tube for $7.79. Squeeze some out of the tube and smear it thoroughly into metal threads to keep them from seizing and galling due to corrosion and heat. Among the many problems that can attack the threads of nuts, bolts and screws are metal galling and friction welding that can occur during over-aggressive or incorrect assembly and leave little chance of separating them later, except by cutting, drilling or twisting them apart. To prevent this, it’s a good idea to use anti-seize compounds such as Star brite Anti-Seize Thread Lubricant during assembly and re-assembly whenever possible.
The battles against corrosion and thread seizing might seem like a lot of hassle, but the real hassle begins if you let the problem get out of hand. Avoid that by using the right preventative products to help keep peace between warring metals and keep your fasteners easy to remove next time something on your motorÂhome needs service.Â
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