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After Installing new bushings for a new heat riser butterfly valve, I noticed a hairline crack just above each bushing. Above one of the bushings, it appears that the crack might have been there for a while.
The other might be new and happened when the bushing were tapped in. The casting is only about a 5/16 inch think in this location so I was concerned with a crack occurring.

I could be wrong but I would think that any leak from these cracks would be lest than what could come out between the heat riser shaft and the bushings.

Is this common?

Has anyone ever dealt with this before?

I could have a machine shop weld those two spots but I wonder if that is even while. I have a MIG welder but have never tried to weld cast iron and would not know if there is a wire that could do it.
If this was steel I would just file a v using a triangular file or a Dremel wheel and then just weld it back in.

Thanks for any advice or comments you all can offer.

Cracked exhaust manifolds are common on the 230 when the exhaust hangers fail and the owner doesn't notice. All that weight eventually cracks the manifolds; however, not where you describe it.
Better to replace the manifold than to try welding pot metal in my estimation.
Gary

I had a crack in my 230 exhaust manifold that was on the front runner. The crack was about an inch long. I took mine to a mechanic that had a special powdered metal which had cast iron and possibly zinc. Great job, cost $75. These are known to crack and the cost for a new one is around $200-250. My suggestion is to find a good engine rebuilder or welding shop. They can get it repaired and save you some $.