[77newell]

A few thoughts/questions.

Is the general location of the leaks consistent or random?

The mass of the radiator is carried somehow between attachments top and bottom, suspended at the top, held up at the bottom. And thinking about the total mass, including water, being jounced around going down the road is really complex. It’s not clear to me how the weight is carried and how the horizontal loads are carried. There are dynamic loads in both directions when the coach is moving.

Richard’s statement about flexibility lead me to wonder about flex caused by the drop in pressure by air as it is sucked through the core. Given the area it wouldn’t take much drop to generate considerable force that probably peaks in the center of the fan disc.

I think I recall this previously coming up, but how are commercial bus radiators constructed, the tubes oriented, and mounted. It may be useful to talk with a bus repair facility that works on multiple brands, find out which has the least problems and then dive into the details that explain why.

No need to respond to these thoughts. I offer them as food for thought.