| May/June 2001

This month, I'm passing on some varied advice from contributors to the internet Stationary Engine Mailing List to solve the problem of a cracked water jacket.

The initial question: We've had numerous discussions on welding cast iron in the past. People that I know to be knowledgeable have posted detailed descriptions on what to use and how to use it. All that aside, I still don't feel enough confidence in my ability to tackle an engine. We've got a 6 HP FM Z with a thin crack in the water jacket that extends from the head back to the base directly below the cylinder. It's virtually non-existent when cool, but as the engine runs, a steadily increasing stream of water begins to make its appearance. It's pretty bad after a while. Anyway, because it's in a high-stress area, I figure it will have to be welded. My problem is that I haven't had much luck locating someone in my area that is experienced in welding cast.

And in response: For the last seven or eight years I have been using a welding rod designed for dirty castings. No preheat, no grinding or cleaning, no stress relieving, machinable (unlike Ni) and it welds right through rust and dirt!!!

It takes a different technique but saves a lot of work and has a higher success rate. I have had great luck with it. The rod is Weld Mold 706the manufacturer is in New York but I get mine from a small specialty weld supplier.

This rod seems to burn right through the rubbish. I have done as much as six inches of continuous weld without trouble. The only place I have had much trouble is right next to the exhaust valve or on an exhaust manifold. The first pass always looks a little bubbly, but just chip and brush and weld right over it. Comes out smooth as satin. The results are the same color as iron and can easily be drilled and tapped. I think the reason it works so well is that the expansion and contraction of the weldment matches that of iron. (Ni and stainless contract so much during cooling that the weld pulls from the iron.)

The best cast iron rod that I have ever used is the Palco 808 rod made by Precision Alloy Company of Scottown, Ohio. They really 'flow' well and are easily machinable. You can use them to weld steel to cast with good results (those of you that are familiar with alloys know that this can be difficult).