How To Repair Cracked Cast Iron Cylinder Head

Cylinder head, or sometimes referred to as just the head, is found in most engines, including your car’s engine. In most cases, cast iron is the preferred material for cylinder head due to its ability to withstand high temperature.

Cracks in cast iron, however, are not impossible. Due to the constant exposure to high temperature, cylinder heads made out of cast iron can crack over time. If you find yourself in the situation wherein you find a crack on your cylinder head, then prepare to repair it by yourself.

The first step is to clean the metal parts of the cylinder head. As cast iron absorbs oil greatly, cleaning the metal from oil debris is recommended before you attempt to repair the cracks. Cleaning can also allow you to visualize the extent of the damage. Use a degreaser to remove all the oil. Bring the cylinder head to machine shops to cook the metal in a vat with degreasers. Once you have successfully removed all the oil, work on repairing the crack within an hour. If you are seeing a junk shop for the degreasing task, ask for a small scrap of cast iron metal for you to test your welding skills before working on the actual cylinder head.

Inspect the crack. Some cracks are due to overheating while some are due to stress. If you find a visible rack, then you should use a drill to make a hole near the end of the crack. You will need to make a small channel along the area where the crack is. You can use a small grinder for this step. This will allow you to come up with fresh metal for you to weld on.

Cracks due to overheating can be difficult to see. If you can’t see the crack by just looking at it, then use a dye to assist you in locating the crack. You can purchase a specialized dye for visualizing cracks in any welding supply store. Spray some dye on the area and wipe it off. Areas with cracks will manifest the remnants of the dye.

If you do not have the dye, you can use some foot powder to sprinkle some on the area. The white powder can show the traces of the crack. Clean the cracked area with a degreaser. If you intend to do the project on your own, it’s best to have the complete set of chemicals for you to work on.

Once you have cleaned the area, prepare to move to the welding process. You will need to set up your welding machine in a high temperature, to about two hundred degrees Fahrenheit. Use a welding rod that has a small diameter. Allow the rods to heat up before you use them. The oven is the best place to heat your rod.

Depending on the welding machine that you are using, the process can vary. Check out the machine’s guide for you to follow. Fill the area by welding through it. Let it cool down by applying weld blankets to hold off the heat. Do not scrimp on the welding rods that you will use as the result can be compromised. 

Before you start welding, arm yourself with protective gears and glasses to avoid hurting yourself.


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