Kurt,
As a prudent course of action, it is always safer to follow procedures that have been tried and tested. These procedures are the welding and drill-out methods which have been a popular recommendation by many. And I strongly agree with the above methods. However, I have an idea that may shock the experts.
The protrusion of the dowel pin on the crankshaft pulley is about 3.5 mm based from my sample.
The total depth of the hole on the end of the crankshaft is about 9 mm.
Here comes the delicate part.
1). The dowel pin on the crankshaft pulley is not welded and could be moved slightly (in/out) as needed.
2). Since you only need about 3.5 mm or less protrusion for the dowel pin, there might be enough room or space after pushing the
'broken piece' in all the way. Unless residual material from welding is not removed. Drill-out method would help reduce some material that could create more space.
3). The measured depth of the hole is about 9.0 mm. The broken piece wedged in the hole could be between 3.0 to 4.0 mm. Theoretically, there is still about 5 mm of space available after pushing the 'piece' in.
4). To be conservative, let say only 80% space is actually available, that would be
4.0 mm.
5). The crankshaft pulley with 3.5 mm dowel pin protrusion could be mounted conveniently. Worse scenario, adjust protrusion to 3.0 mm.
Based from the above information, I strongly believe that it is feasible to mount crankshaft pulley without taking out the
'broken piece'.
Tony