Soldering is a skill that's very easy to learn. Knowing how to solder broadens your ability to work on your car. If you can solder, you can repair a leaking radiator and can make many electrical and non-electrical connections quickly and securely.
Most metals around the home and shop -- such as brass, bronze, copper, lead, nickel, silver and tin -- can be soldered easily. Probably the two most common automotive jobs, though, are repairing radiators and making electrical connections.
There are two types of solder you'll be using -- electrical solder and non-electrical solder. If you're soldering two electrical wires together, use electrical solder (electrical solder has a rosin-core flux); for a non-electrical item, such as radiator, use acid-core solder (this contains a acid flux).
What is a flux? Basically, it's a material that removes the oxides from the metals to be joined, so that a secure bond can be made.
One last thing to bear in mind, before we get into how to solder: Solder by itself is very weak. It should be thought of as the final binding of a joint, not as the primary means of holding the joint together. That means a soldered joint should be mechanically strong before solder is applied.
If your soldering iron or soldering gun is new, the first thing you want to do before actually soldering is to tin the tip. This allows maximum heat transfer from the tip to the work to be soldered.
Holding the solder against the tip, let the gun or iron heat up until the solder melts and wets the tip thoroughly. Turn the iron or gun off and wipe the excess solder from the tip with a damp sponge or cloth (take care not to burn your fingers on the hot tip).
The tip should be retinned whenever it gets dirty or when solder won't cling to it, and instead rolls off in balls. Before retinning, clean the tip with a file, emery cloth or steel wool until it's coppery-shiny and smooth once again. Then tin as described earlier. ELECTRICAL WIRES: When joining two electrical wires, remove enough insulation from each wire so that the wires can be twisted together for a strong mechanical connection.
Now let your gun or iron heat up and place the broadest portion of the tip against the joint, for maximum heat transfer. Touch the solder to the place where the tip and wire meet. Let the solder melt around the joint -- once the solder starts to flow, you can move it around the joint a bit so it flows through the joint thoroughly. Once the solder has melted around the joint, remove the gun and the solder. Don't move the joint until the solder cools.
Then cover the joint with electrical tape. That's all there is to it.
If you want to practice, buy a small spool of 16 or 18 gauge multi-strand wire at your local auto-parts or electronics store. Once you've soldered a couple of joints, you'll see that it's very easy. NON-ELECTRICAL CONNECTIONS: The same technique applies as above, except the solder used is acid-core solder.
Let's say you're soldering the leaking seam in a radiator. First clean the seam with steel wool until the seam is bright and shiny.
By the way, any joint to be soldered must be clean, or the solder won't make a good bond.
Now apply acid flux to the joint (acid flux can be bought at auto-parts supply stores) with a brush or piece of paper. Don't use your fingers. Heat the seam with a soldering iron or touch -- a small wattage iron won't provide enough heat for a radiator seam.
Then apply the acid-core solder to the seam, moving it along the seam until the seam is sealed. Remove the soldering iron or torch and the solder, and you're done.
Sometimes a leaking radiator can be repaired in the car, and sometimes the radiator can be removed. If you're going to use a torch, remove the radiator even if you can get at the leaking seam easily. You don't want to take any chances on starting a fire in the engine compartment.
It goes without saying, of course, that the radiator should be empty when you're working on it. That means draining the coolant. Don't drain the coolant until the engine is cold.
One word of caution: If you have never soldered before, it's probably best to let a radiator shop repair a radiator leak . You want to apply enough heat to the leaking point to melt the new solder and form a good bond -- but on the other hand, you can, if you're not careful, apply too much heat to the adjoining area, loosening that solder and causing a leak there.
Soldering wires and most other solderable connections is easy. But soldering a radiator is more difficult. BUILDING YOU OWN LOGS A couple of readers have written in with tricks for making their own firewood by rolling newspapers into logs. The first is to use the wire made for tying plants to bind the logs tightly after rolling. This wire is a lot like the twist-on ties used for sealing plastic bags, but it's sold in garden stores in long rolls. It's easy to handle and so fine it all but disappears as the log burns; no heavy chunks of wire remain in the ashes.
A second reader binds logs with ordinary string, then stands them in a wash tub and lets the water from the washing machine drain-soak them. After the soaking they're stood on end outdoors to dry. The soaking binds the paper layers together and produces a longer, steadier burn.