Fixing a freeze crack (Cast welding question).

Here's one for you all: Observe the drawing: http://www.tremel.net/EngCrack.gif My welder, who can weld just about anything, is having problems with the top crack. He does the usual such as (Bake the cylinder to 500 degrees, tack the crack with nickle rod, etc...) The cylinder would cool and the crack would open up. We had never had this problem before. We are thinking that the two hairline cracks the protrude through the stud may be causing this pain. Any thoughts on keeping the metal in place? Should we try some other rods?

Hi Bill

The first thing I would do is save your ni-rod for welding nickel . Spend the bucks and get some of the newer style cast iron rods . They are soft to machine , just like cast , and they have the abillity to stretch when they cool and not crack !

Good luck

Brian

As what mr. Triebner said, remember to heat it up first then weld it. using this and the iron rod should cure the problem. Good Luck. Corey

I'm going to have differ with other responses. First, there are numerous grades of Nickel welding rods. The BEST we've ever used (and we weld for a living--old engines and tractors too!) is WELCO Nickel 99 made by Harris. Secondly: the reason you are cracking upon cooling is because you are heating it in the first place. The idea of using Nickel is to NOT heat the parent metal. Weld short passes and peen so as NOT to heat up the weld area. I welded the entire bottom of a 20-40 Case crankcase this way with no problems, except nearly going deaf, even with earplugs, from all the peening. There are cases where, if a huge amount of repair is required, the entire casting MUST be heated. But in these cases the casting is heated ENTIRELY to red hot and gas welded with CAST IRON rod and cooled VERY slowly. Not in the scope of the average shop!

Hi; I agree with Craig, I have had pretty good luck with 99 % nickel rod. It is soft, strong and responds well to piening to relieve the stress. The trouble with most cheap cast rod is it's too hard and will crack next to the weld. I welded a 5 inch crack in my 16-30 Rumely block along with other parts and had good luck over the years. I preheat some cast parts that have been impregnated with oil to drive the oil out then let them cool before welding. Do about 1 inch at a time then pein to relieve stress and move on. Good luck....


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