Classic Lincoln Automobile Restoration
Lincoln Model L Engine
Welding Cast Iron

This article is about repairing a Lincoln model L cast iron water pump, but it also applies to repairing cast iron in general. While disassembling and separating the front and rear halves of the water pump, the flange surface of the rear half broke. This occurred because too much pressure was exerted on the flange. In hindsight a better way would have been to first soak the shaft and bearing/packing areas and then gently press on the shaft and impeller to separate the halves.

To master the repair of the water pump’s flange, I turned to a previous acquaintance, Cecil Muggy, a retired metallurgist from Boeing. Years ago I contacted him for soldering and repairing the aluminum body on my type 177 touring. Since then I learned that Cecil has fully retired and turned the reigns of the company over to his son, Mike. Muggyweld now offers a complete line of welding and soldering products for difficult problems such as the cast iron water pump housing. They offer two grades of arc welding rods, #72 for heated affected cast iron that would be used on exhaust manifolds (also referred to as dirty cast iron) and the #77 for “clean” cast iron which also can be machined. Their claim is that their cast iron rod has 300 percent more elasticity than standard nickel arc welding rod. They also claim that preheating of the area to be repaired was not necessary, though my experience varied here.

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Before trying to weld the water pump, an old marine cast iron manifold was retrieved from the junk yard and several cuts were made and V’d out. Using about 90 amps, negative polarity, and a back stitch method, the rod penetrated the scrap manifold well. In one small area a crack appeared across the stitch where there were two different thicknesses. Going over the area again corrected the crack. I believe this is where some preheating may have prevented this from occurring. Otherwise I was delighted the #77 rod would solve my problem. The water pump housing and flange pieces were bead blasted and a thick aluminum plate jig was fabricated to bolt & hold the flange pieces. Again using the back stitch method, short welds were applied on both sides of the broken flanges. Afterward, the welds were machined using pneumatic and Dremel carbide grinders. Also, the cast iron rod was used to fill in heavily corroded areas around the water pipe flange.

Repairing cast iron has historically been difficult, however this welding rod may offer solutions to once un-repairable parts like the bottom edges of the cylinder blocks. Muggy weld offers many products to include a special low temperature solder for things like pot metal repair. Don’t confuse or write off this soldering rod as the typical flea market “beer can” product. Their web site offers a great deal more than can be explained here such as video tutorials. Company information: Muggyweld, P.O. Box 11927, Olympia, WA 98508-1927, phone: (866) 684-4993,
See special article on cast iron repair of a 1930 model L Lincoln water pump at

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This page last updated on
30 October 2006