As the puddle grows you can allow it to cool and solidify at one side while you add metal where it's still molten. In this manner you can continue to add metal to build the part up to a shape which is roughly equal to. The properties of cast iron are different to those of other metals and it will crack irreparably if you do this. The solder solution will have a semi-permanent lifespan, but do be aware that it is strongly advised that you replace the manifold with a. Step 4 - Check for Obstructions. Once you have completed the job, check the underside or inside and make sure there are no holes or obstructions. Hopefully, having completed this, your exhaust manifold will have a solid finish and be secure enough to replace onto. Otherwise you may need to drill to the major diameter and install a Heli-Coil for thread repair. An alternative to drilling may be to burn the stud out with an ELOX machine (Electronic Discharge Machining). A squeaky tight enthusiast such as myself might have the urge to weld this back together. If you should mention this to a friend you may hear the immediate comment that you cannot weld cast iron, and especially a part that has been repeatedly heat. Once the manifold is clean, allow it to dry. Grind the area to be welded. Grinding the cracked area of the manifold removes any debris or rust that may have built up in the surface of the crack, and also provides a clean place for. The key is to penetrate deep enough to really repair the area, instead of simply patching up the surface. Move very slowly when laying the weld to create a big molten puddle. If the welder is a stick unit, most areas of the manifold should. The manifold is bolted to the engines head. A leaky intake manifold interferes with normal engine operation. Once it is determined that your intake manifold is leaking there are only. Exhaust problems are reasonably easy to pinpoint, but if not repaired, they can cause noise. If the stud has been broken off near flush so you can't get a grip on it, then it might be drilled out. If you are very careful about drilling concentric to the threads, you might then be able to clean out the original threads.