Tips for repairing an exhaust manifold crack include removing the exhaust manifold from the vehicle first, cleaning the damaged edges, using a welding torch and silver solder to fill the crack and allowing the manifold to cool on its own before reinstalling it. Gather the required tools before starting the repair. Wear safety glasses, welding mask and gloves while working.
To fix an exhaust manifold crack, unfasten the cracked manifold, set aside the bolts for reuse, pull it out, and place it on a working surface. Assess the size of the crack. Seek the services of a trained welding specialist or replace the manifold with a new one if the crack is large.
Clean the surface of the manifold, and scrape the edges of the crack with light pressure. Clean off iron filings from the inside of the manifold with a clean lint free cloth. Put a silver solder against the damaged edge, hold a welding torch close to the crack and evenly solder the crack, using the lowest heat setting. Consult a welding specialist if you have never done soldering before. Fill small holes with a special welding compound.
Once all cracks are repaired, wait a few minutes for the manifold to cool naturally. Place the manifold in its mounting position, and bolt it in place with the retained bolts. Test the repair.