As I posted several weeks ago, I had just taken off on my way to the Factory Fly-in when the lady yelled in my ears "engine temperature, engine temperature" and I looked down and CHT was rapidly climbing in the red. It was passing thru 360 F so I immediately throttled back to slow flying speed; it then settled in at 350 F and stayed there while I did a 180 back towards home. Keeping airfields under me at all times I limped for 15 minutes and landed back at the home field. A quick inspection with the cowl off showed coolant dripping from the bottom of the radiator and the belly of the plane and tailwheel wet with coolant. I opened the radiator drain plug and only got about a cup out, so it was nearly empty of coolant. A subsequent pressure test at a local radiator shop showed a split tube in the radiator core. Thru the whole incident the oil temp and pressure stayed in the normal green range. WARNING! FWIW the coolant overflow bottle was 3/4 full at the end of the flight when the rest of the system was empty! So be aware that a full overflow bottle does NOT mean your system is anywhere near full-you must check at the spider tank cap.

My failed radiator was the older brass/copper style. Today I just finished installing the new Kitfox aluminum radiator. It appears to be a much sturdier welded aluminum unit with stronger tanks and top and bottom supports, compared to the old soldered together unit. I understand all Kitfox Rotax FWF kits have come with this new upgraded radiator for the last several years. I wish I had known; my incident could have turned out far worse. The new aluminum radiator is a little thicker and taller and mounting holes are somewhat lower, so I had to make new mounting straps (3). Other than the new straps it fits in just fine and the existing hoses also fit. Installation is fairly straightforward as long as you take care to make the bottom and front face come out the same as the old radiator. I mounted the oil cooler on the front face using quick ties just like on my old radiator so that installation was quick and easy. If you are using the SS straps to mount the oil cooler they will need to be redone because of the taller radiator height.

Did a test flight today and everything seems good with temps all normal. By the way, I also went thru the Rotax Maintenance Manual procedure for exceeding engine coolant temperature. Since I was at 350 F for less than 30 minutes it required a thorough inspection and repair if needed of every coolant system component, and a torque check of all head bolts. Everything checked out good except of course the radiator.

I hope my experience may help encourage upgrading to the new radiator, as well as checking your coolant level often AT THE SPIDER TANK.