I have always (never failed) with this method.

Soak with PBlaster, let sit for about 2 hours.
Put large wrench on nut
Cover any area that can be damaged with a folded towel
Smack large wrench with a mini sledge

One good whack is all it has ever taken.

To put the fan back on, there's a trick that E39 people shared. Put a string on the bolt. Hold the fan blade to align the bolt on the WP thread. Pull the string to spin the bolt on. Then you can use the wrench from there.
No need to torque it since the WP shaft will rotate to tighten it (that's the reason for reversed thread) when the engine is running.

I had a very difficult time getting the nut loose as well. Car has 80k miles and the thing was on there tight. I finally got it loose by crawling under the car, pulling down on the belt and with a strap, tying it taught to the subframe bar. With the added belt tension, one whack got it loose...

I'm pretty sure your ghetto-fab tool was the culprit....I fought like crazy to get mine off (on an e36 with 180K miles) until I bought the correct tool. Took two seconds. Its really not even on their all that tight. When I did my e53, it took a little while longer, but basically once I got it hooked up right, it went right away.

good luck.

I feel you man... I done it on mine 6years ago .. The scar on my right elbow still here with some of the dirty stuff ( grease , oil etc..) in side my skin .

Hey guys,

Follow up to my problem.
I had to concede to this one after spending way too much time on it. I had made a good tool that held the assembly well. Got a wrench on the other end and had soaked the nut multiple times over the two days with WD40. Used a dead blow hammer on the wrench multiple times and the nut never budged and neither did either tool.

Finally ended up towing it to my local import guys who weren't worried about the job at all. They called me a few hours later to say the truck was ready. The result? A 3 foot long chisel they had to use with a big ass hammer to whack the corner of the nut repeatedly until it finally broke loose. It wasn't cross threaded but it was on there tighter than it ever should have been.

I appreciate the comments and the votes of confidence but I drew the line when it was obvious I was going to have to get ugly with this thing. I definitely was not doing anything incorrectly nor was the tool I fabbed to blame. That was all good. The issue was the amount of ugliness that had to be used to get the nut to break free.

The tow cost 65 bucks and my mechanic only charged me 165 to completely finish the job including fresh coolant. I lost on this one but won with the deal they gave me.

Cheers
Bernie

I gave up using the proper tool long ago. $15 Craftsman open end wrench (thinned it down with a grinder) + a 3lb hammer works every time. No penetrating oil is needed. The 3.0 is much easier than the 4.4. Seems like the belt on the 4.4 isn't ever tight enough. Always hit at a tangent angle like was mentioned before and watch where the wrench is going to go when the nut comes loose. It sucks if you damage a hose or fitting.

WD-40 is not a penetrating oil. It's a good attempt at having just one can that does everything, just not very well. Here's the short list of comparisons of penetrating oil effectiveness.
Best Penetrating Oil Test, surprise winner - Ford Truck Enthusiasts Forums

WD40 is more of a cleaner than anything. For penetrating oil PB Blaster all day.