free frozen flare nut at radiator?

Are you replacing the line? Isn't there a flare seat that screws into the radiator and then a flare nut that actually screws into that? I would leave the flare seat in the radiator and then use a backup wrench on it, then put your flare wrench on the flare nut and squeeze the two together with one hand (that way no torque or bending force gets transmitted to the radiator.) If you're replacing the line completely, just cut it off and slip a 6 point box wrench on it rather than a flare wrench. If you're trying to save it, use vice-grips to hold the end of the flare wrench shut.

Where is the line leaking? If it's not at the fitting, and you are trying to avoid an expensive repair, it may be easier to cut out the damaged section of line and splice in a short piece of hose.

WARNING:

you MUST use transmission cooler line for this. Fuel line will not work. I have personal experience with this, the end result was a car flambe and a slipping trans after the fuel line burst and dumped trans fluid on the downpipe (I didn't install the fuel line, just didn't identify and replace it until after it'd burst.) For safety, I would probably take a double flare tool and form a small "bubble" in each cut off end, and also make sure you use the high pressure style clamps.

good luck

nate

I have used a product called "Kroil" as a penetrating oil. It works better than the stuff you find at most auto stores. Find them on the net, I think

I've drowned it in PB Blaster, which has worked in other places. (Frozen bolts around the gas tank, in particular.) In this case, I don't think it's penetrating the threads - it's like there's almost a glaze on them. Wire brushing hasn't helped a lot, but access is difficult.

PB Blaster is pretty good; probably the best stuff you're likely to find at your FLAPS. I have used Kroil and Wuerth Rost Off with better success, but those are more expensive and likely mail order only. I think the Wuerth product is probably the best I've ever used, with Kroil a close second.

nate

Well, I got it out. I made a heat shield out of some old sheet metal, and then applied (not a lot of) heat (propane torch), and a little more force using a breaker bar.

Thanks to all who replied.