When you take the front cover off it opens the top of the upper oilpan, so when you go to pull the water pump out the coolant that is behind the pump splashes out and since your oilpan is open it can drain in there which is no good. I edited a picture to show you, but photobucket is down for maintenance right now so i cant load it to this post. I will post it later on tonight (for me) tomorrow for you probably. What i did for mine, was i got some pigmat, its an absorbent material that only soaks up chemicals but repels water. stuffed it in my oilpan so that nothing could get in there, and then made a kinda run off with it, if that makes sense. that way when the coolant came out it would just run off on to the ground and not into my oilpan. you might can stick some rags in there but they will soak the water up and you might get some residual in your pan. Once i get the picture up you can see what i mean and i'm sure you will figure out your own way to prevent the water to get in there. Are you thinking of doing this? if so, have you ever changed a timing belt or chain before? the reason i ask is because this one sucks real bad to do, and if its your first one you are gonna want somebody that has done this type of maintenance before so you dont ruin anything. if you got a 4x4 the alt. and power steering pump suck to take out. I found out later that if you take the wheel off and pull the plastic wheel well, it will make your life a lot easier. Also, nissan puts about 3 gallons worth of RTV on that cover, so its rough prying it apart. It honestly made my a$$hole pucker up cause i thought it was going to snap in half.