Been trying to make a safe hood hinge spring expander but gave up. Could use a cherry picker but used a floor tie down and overhead hoist. Used ropes to not damage the factory finish and probably could do one in 20 seconds once the ropes are set up. Hope someone can use the tip.
Dustin

 

I just use a tire iron and pry it off and on the same way one would do brake springs.

 

Once you get it expanded, insert a box nail between each coil. This holds the spring expanded so you can put it on the hinge. Lower the hood and the coils expand, allowing you to remove the nails.

 

I've successfully done something similar to what Joe suggests. I made a frame of heavy angle iron with holes where I hooked on the ends of the springs (the two in parallel) plus three threaded rods (one between the springs, and one on each side). Crank the nuts on the rods to expand the springs. Send the whole assembly out to re-phosphate the springs (of course alternatively they could now be painted). Using a floor jack like Joe shows is particularly clever if you don't need to refinish the spring--I never of thought of doing that.

I have a pile of thick nylon fender washers. When I get the assembly back from metal finishing I slip a washer between each turn of the springs, loosen the nuts and remove the expanded springs. If you're concerned about the washers slipping out, you can insert a wire down the stack of washers' center wholes. Slip the expanded spring on the hinge, and just like Joe, lower the hinge and the washers fall out.