I have a cinder block fence in my front yard that has two courses of cinder block and a row of cap blocks. It is about 24" high. It is set on a very nice, solid cement footer. I want to add a 48" chain link on top of it. If I drill holes to accommodate my corner and line posts, and break out the mortar that has probably filled the interior sections of the cinder blocks all the way to the footer and set them in cement, would the harder cement support for the posts take enough of the stress off the bricks to keep it from cracking the rest of the cinder block fence?
I would get posts for a six foot fence to compensate for the wall height. Then anchor the posts in the ground. Then set the fence height to be level with the cap. If they didn't fill the blocks, the caps aren't thick enough to get a good length of anchor in.