Yes, the engine was out and very clean.
It needs to touch conductive surfaces like metals, be sealed away from oxygen for a while, a week is good. It continues to set months later. It stops being dissolvable after curing. It only works for metal to metal, and only if the gap is paper thin between the metals.
I haven't seen an old tube fully cure, but seen one get lumpy. Not sure how the physics of it works, but maybe something to do with conductivity.