Uniquely, our house has a huge chimney, almost 12' long and 2'-6" wide. And due to 57 years of weathering, let's say it's seen better days. Our original intention was to have a new metal cover made for it as part of our roof contract. Since our roofer was unable to secure a metal band around chimney cap supplier, we ended up having to deal with the existing chimney crown. Every time we would get a heavy rain, we'd get a few drops in our fireplace, not good. I chiseled into the fossil like layers of said crown to the left only to find cmu coursing stepping up, thus the large mound of seeming concrete on our chimney.
With a little research, I found a great product called Crown Coat from a local supply website. One evening I did all the prep work to the existing cracks then taped it all off before applying the product. It's like painting thin concrete and dries pretty quick and evenly. Although a temporary fix, I'd say the money was well worth it for a 15 year warranty product. After a good rain I inspected the results to see the crown was shedding water as well as most of the new roof. The next step before winter is to do some tuckpointing repairs on the rest of the chimney. Hopefully I can find someone to fabricate a cap down the road, aka next year.