I had an impact wrench but ....afraid to twist the bolt off. The bolt is about 5 to 6" long. You have to take the radiator and shroud out, no question about that on van.

 

hi when i replaced my waterpump i had 3 bolts snap on me and the shop had to take the timing chain cover off to drill the broken bolts out.@ thaT time i went ahead and had them replace the timing chain and gears in there.the shop told me some 1 used loctite to seal the waterpump bolts in place.(this is the reason i had 3 of them stuck in place.i do not recommend using loctite in the threads of the waterpump or any bolt threads for that matter).hope this has helped