How to weld an engine block cast iron

Cast iron is a very strong material and when it is not damaged, it may be difficult to repair the damage. It is possible to weld repairs in cast iron, but it is important to complete all the necessary steps to prepare the molten iron for repair. Consistency is important when working with molten iron, as there are two common approaches for welding cast iron – either cold or hot soldering. Although both methods work, it is important to choose one and stick with it until the repair is completed. Things You ‘ll Need
welding torch welding
protective clothing and gloves
Nickel soldering electrode 99 sticks
cast iron engine block
further instructions
heated welding
Preheat the damaged engine block before welding. If possible, heat the entire engine block at a temperature of approximately 800 degrees. Adjust the engine block in an area that is closed without strong air currents to prevent the engine block cooling too quickly. If it is not possible to heat the entire engine block, heat the area around the repair.

Adjust the welding torch to a low current. This will minimize the creation of additional stresses caused to the engine block cast iron during repair.

Apply the nickel electrode and start filling the crack in the engine block with a movement back and fro through the crack. Take care to ensure that nickel smelter flows on either side of the crack.

Allow the cast iron block cool slowly, once the repair is complete. If necessary, the engine block wrapped in insulation blankets to slow the cooling rate. The slower the engine block cast iron cools lower the risk of repairing cracks and separate from the engine block cast iron.
Cold welding

Prevent cast engine block casting be hotter than 100 degrees Fahrenheit.

start applying the nickel electrode at the bottom of the crack and work in an upward direction of the crack. Move the nickel electrode so that each weld bead moves in the same direction of the previous.

Allow the weld to cool slowly once the crack has been filled and complete repair. Do not accelerate the cooling process with water or air pressure as it could lead to new solder to crack and separate from cast iron block., and Use Slag removal.