I guess now is as good a time as any to do a write up. It all depends on how much room do you want to work with.
You do not have to remove any hoses, nor the alternator. You do not need to lower the engine (unless you need even more room, but that is just more work).
Majority of the work to change out the water pump is done thru the bottom of the car. I don't know if you can take out the pump from the top, doesn't look like there is enough room. EDIT: After looking at the pics it looks like the pump MAY come out from the top if you take off the engine mount. In that case do everything but skip step 6 and 13. However, to make it MUCH easier to get to all the water pump bolts, I recommend removing the crankshaft pulley.
I changed the water pump when I replaced my timing components. This is what I did. You don't have to do it in this exact order. This was done on a 1993 Nissan Sentra XE, GA16DE motor.
REMOVAL
1. Raise car.
2. Drain coolant by removing radiator cap, loosening the radiator plug on the bottom and the plug on the engine block...
3. Remove the plastic covers from the underside of the engine and around passenger wheel well. Looks like this when its done....
4. Take of all the drive belts. Loosen the idler pulley to remove the A/C belt. Loosen the P/S adjusting bolts and the pivot bolt on the pump itself to remove the P/S + water pump belt. Loosen the adjusting bolts and the pivot bolt on the alternator and rotate it to remove the alternator belt. Most people have problems removing the p/s + water pump belt ( i did too). You just have to remember to loosen that pivot bolt. Then you can rotate the p/s pump. Here is the pivot bolt...
5. Next remove the head cylinder mounting bracket, this gives you some access room to the water pump from the top. It is held on by 3 bolts. Disconnect the O2 sensor + the other connector and move the bracket out of the way. Coolant reservoid can also be removed (it pops off).
Now, if you want more room, you can also remove the engine mount and its bracket. Make sure you support the engine first. Here is how it looks without the mount...
6. Next, remove the crankshaft pulley. Now there are many methods to do this such as impact wrench, breaker bar, etc ... A trick I learned from these forums, is to first relieve fuel pressure. Then you'll need a big wrench and a 27mm socket. Put that on the pulley bolt and rest the wrench against something solid, like so....
Crank the car just for an INSTANT and the bolt WILL loosen.
To get the pulley out, some people are able to just pull it out, I had to use a pulley puller.
7. Next, remove the thermostat housing. It is bolted to the side of the water pump by three bolts. These are a pain to get out, so have an extension and a swivel ready. Bolts are 10mm. Here is the thermostat housing... There are two bolts on top and one on the bottom.
Can't really see them from the pic above, here is a better pic of the housing...
8. Next, remove the water pump pulley, 4 bolts, 10mm. And then remove the water pump.
Here are the bolt locations for the pump, again 10mm.
9. Clean off any old gasket with a scraper or razor blade, I use a little sand paper to smooth things out. Clean all the surfaces with brake cleaner.
INSTALLATION
Word of advice, use a torque wrench when tightening things back up. When tightening the water pump, use a cross pattern.
10. Apply Ultra Grey liquid gasket to the surfaces.
11. Install water pump.
12. Install thermostat housing.
Then everything else is self explanatory.
13.One last thing, when you have to tighten the crank pulley, there are different things you can do. If you have a manual transmission you can have someone put it in gear and hold the brake pedal while you tighten the pulley. If you have an auto, like me, you can take the off dust cover on the bottom of the transmission. Stick a wrench in the flywheel so it doesn't rotate and then tighten the pulley.
Attached to the dust cover are two metal gussets. Everything is held on by two bolts. Once you take out the bolts the gussets can be rotated a little to give you room to remove the dust cover. Here is a pic with the cover off. (Yes the cross member is removed in this pic)
14. Once everything is assembled, follow the procedure in the service manual for refilling and bleeding the coolant system.
Good luck. It is not difficult but will take some time.
I did this about a month ago, so I'm writing this up from memory. If other people have any advice or corrections, please post them.
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