Rounded Fan Clutch Nut

[RoundHead]

I have a 1991 Ford Aerostar 4.0L. (I realize this is a super coupe forum, which is why I'm here. As a forum for sportscar experts, I presume that there are a number of very knowledgeable mechanics likely to see this post.)

I was "helped" by someone recently who decided to assist me in the removal of the fan clutch from my van. He made the assumption that the fan clutch bolt had a left handed thread, and turned it to the right (while facing the vehicle). I had indicated that I would prefer to wait until I had the part that would confirm the proper direction to turn the nut. He tried to go further, and started to round the heads after completing roughly one third to one half of a turn.

I have the fan clutch removal tools rented from AutoZone for this vehicle. The open ended wrench that is part of this set of two tools (in addition to the water pump pulley holding tool) seems to be a little too large and a little too inclined to open up. The fan clutch nut (which is an integral part of the fan clutch) is also fairly rounded from attempts to use it while applying substantial torque.

I've had a few suggestions with regard to how to get this rounded fan clutch nut off of the end of the shaft that connects it to the engine.

1. Use a plumber's wrench. (This won't work because by the time one loosens the pulley bolts to get the pulley holding tool over them, there is barely a quarter to half an inch of width in which to place a wrench to turn the now rounded fan clutch nut.)

2. Use a 1 5/16'' open ended wrench instead of a 1 7/16'' open ended wrench, as provided with the fan clutch removal kit for this vehicle. (I haven't tried this yet as I don't have a 1 5/16'' inch wrench and getting one requires a vehicle and another trip out and down the long road into town. I've done this three times this week trying to get this vehicle repaired, and would probably be done by now were it not for the "help" that I received). I believe the 1 7/16'' wrench may have been slightly too large, contributing to the rounding of the heads when place under considerable torque.

MY QUESTION IS THIS: How to I get this fan clutch off of my van? The radiator has been removed as another cooling system item that was damaged by the disintegration of the cooling fan at speed. Getting the fan clutch off is the key to finishing this job, but the heads are rounded. OPEN ENDED wrenches (or something like them) are the only things that will work for this application. I have no pneumatic tools. I am seriously considering the 1 5/16'' potential solution, but would like to hear any other valid advice that this forum's members may have to offer in terms of solving this problem.

Thank you very much in advance for any assistance that you might offer.