Planning on replacing mine tomorrow. After 161,000 miles it is beginning to leak around the seal. What all do I need? I have done a search but have not found a conclusive list of things needed. Also on a scale of 1 to 10 (one being the easiest) how do you rate the difficulty.
And from what I've heard, be careful about putting the right bolts back in the right holes. Mine went on pretty easy, and my mechanic skills are very poor. Someone told me that if you put one of the longer bolts in the short bolt holes and crank down too hard on it, you can do damage to the block. If your thermostat is old, I'd pop a new one in there too while the system is drained.
I used a breaker bar to get all the bolts out, but you shouldn't need an impact. None of the bolts on mine were anything too difficult, and none are terribly hard to get too. Just take a piece of cardboard or somthing and stick the bolts in there as you take them out, so you get the right bolts back in the right holes.
I pulled my whole radiator to give me some more space, if youre changing your pump, it's a good time for a fresh refill in my opinion. Bolts should come of with some muscles and a good wrench. Also, I rate the difficulty about a 3.