In this hot weather my little compact tractor (30 hp) gets close to red zone on the temperature guage after about a half hour of hard running. I had been starting to think about a new radiator or at least a flush, then got thinking about a good clean of the fins. One problem with that is the battery is mounted a few inches in front of the radiator. I couldn't get a good shot of air through the fins with the nozzle I had. I looked up air wands yesterday and found a big box store 30 miles away had them, so figured I'd pick one up next time I was up that way.
Last night I got thinking about some air line fittings I took out of the old dairy building when it was being sold off 30 yearsago. This morning, with some fittings, an unused air nozzle and a length of 1/4 inch copper pipe, I made a wand.
And tried it out. I was amazed at the quantity of crap that was blasted out of the radiator! When things dry off again, I will see if I made any difference.
Follow up. Yesterday, I mowed down the 2 - 3 foot high growth in a field next to the creek. The temp guage barely got into the green for most of the hour. It did climb up to the mid point by the end, but when I checked the screen in front of the radiator, it was about 1/4 covered with grass seed. So I guess cleaning the fins worked.