Machines With Air-To-Air Aftercoolers or Oil-To-Air Oil Coolers
SERVICE MAGAZINE, SEPTEMBER 5, 1977, PAGE 5, “Field Repair of Cooler Cores Made of Aluminum”. There is a recommendation in this article that carbon tetrachloride can be used to clean small repair areas of the cooler core. This is wrong. Do not, under any circumstances, use carbon tetrachloride. It is highly toxic and hazardous to your health.
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Some cooler cores that are made of aluminum which have been damaged or leak, can be repaired in the field. Repairs can be made with weld or with epoxy. The weld procedure is normally the best for the heavier parts of the cooler cores such as the end, top or bottom tanks, the connections or the support brackets. The epoxy procedure is normally the best for the tube and fin part of the cooler core.
Procedure to Clean Cooler Core Before Repair Is Made.
Remove all paint, oil, grease or dirt from the area that needs repair. A small knife, file, emery paper, wire brush and/or solvent can be used.
Do not use a cleaner that will cause a chemical reaction with aluminum. These types of cleaners will damage the core.
Trichlorethylene or chlorothene nu can be used as solvents to clean the cooler core. Flush the internal part of the cooler core with a solvent. If the area to be repaired is very small the internal parts can be cleaned by pushing either acetone or carbon tetrachloride through the hole.
Use 4043 welding rod and tungsten inert gas welding process. Any part of the cooler core can be repaired with this procedure, but it is normally easier to weld on the heavier sections of the cooler core.
Use a two part epoxy such as Devcon Special-F Repair Kit-aluminum filled, Devcon EK-4 Kit-unfilled, or an equivalent epoxy.
NOTE: Do not mix the epoxy until the cooler core is ready for the repair. If additional parts such as a screw or a screen are needed to make the repair, be sure that you have those parts ready. Do not mix more of the epoxy than is needed to make the repair.
The epoxy in The Special-F Repair Kit has a cure time (amount of time needed for the epoxy to completely dry) of approximately 8 hours and a pot life (amount of time that epoxy can be used after it is mixed) of approximately 20 to 30 minutes. This type of epoxy is normally used on larger repairs.
The epoxy in the EK-4 Kit will set (become rigid but not completely hard) in approximately 15 minutes or it has a cure time of approximately 20 minutes when a 100 Watt light bulb is used to give heat to the epoxy. The epoxy in the EK-4 Kit has a pot life of approximately 5 to 6 minutes. This type of epoxy is normally used on smaller repairs.
The epoxy will take longer to dry if the temperature is less than 65°F (18°C). A 100 Watt light bulb can be used to make the epoxy dry faster if the temperature is below 65°F (18°C).
Mix equal amounts of each part of the epoxy on a surface that can be thrown away such as a piece of wood or a heavy cardboard. Use a putty knife or spatula to mix the two parts thoroughly. Immediately put the epoxy on the area to be repaired.
If the area is small, it can be repaired by pushing the epoxy into the hole so some of the epoxy goes into the core. Then put epoxy over the hole and the area around the hole.
If the hole is larger, it can be repaired using a sheet metal screw. First push epoxy into the hole. Then install the sheet metal screw and put epoxy over the screw and the area around the screw. Be sure the head of the screw and the area around the screw is completely covered with epoxy.
If the damage is on the side wall of the tube, use paper, gum or modeling clay to fill the area over and around the hole and between the tube and fin. Then put epoxy over the paper, gum or modeling clay on both sides of the cooler core. Be sure there are no bubbles in in the epoxy or air between the epoxy and the paper, gum or modeling clay. This can cause a leak.
If the damaged area is large, a piece of aluminum screen, thin aluminum plate with a few holes or aluminum foil with a few holes must be used with the epoxy. First remove the fins around the damaged area with a sharp wood chisel. Clean the damaged area again. Put epoxy over the damaged area and then put the piece of aluminum screen, plate or foil over the damaged area. Fasten the screen, plate or foil by putting string, wire or hair pin clips around the tube or tubes. Then put epoxy over the damaged area and all of the pieces that were fastened over the damaged area. Be sure the damaged area and the pieces over the damaged area are completely covered with epoxy.
After the repair, remove all epoxy from any tool immediately. If the epoxy becomes hard, it is very difficult to remove.
Do not use the cooler core until the epoxy has become completely hard. Also, do not use epoxy after it has started to become hard.
To improve the appearance (way it looks) of the cooler core, make bent fins straight with the use of pliers. Also, if a fin has been removed, make a replacement fin from thin aluminum plate. Bend the plate to the shape of a fin. Fasten the new fin to the cooler core with epoxy.