Nissan Repair: nissan quest water pump, water pump bearing, seal gasket


Question
My 1997 Nissan quest water pump is leaking on the passenger side of the engine, i see green water coming out drops only its been months doing that,i just add water and keep driving, but now there is a small noise on the side i believe the water pump bearing is going bad, but i am no expert.
the mechanic in my small town not to honest person wants to replace it and replace the timing belt AGAIN  (it was replace 20k miles ago )  for the small fee of $700.00
the question is
can i do it my self ? my local auto parts wants $50.00 for the water pump and the liquid seal gasket but i never done that in a car that parts are on the side

my only mechanic experience is pulling the engine out of my Toyota supra and Pontiac trans am  
i have tools, air tools and air compressor

is it possible that i can do the repairs ? anywhere online i can find some instructions ?
also i don't want to touch the timing belt, van drives like a new Cadillac with 129k miles
thank you for all your help

Answer
Ernesto,

The waterpump acts as an idler pulley for the timing chain.  Always replace the water pump when they replace the timing belt.  This is a commom problem after a new timing belt has been repalced.  They tend to fail around the same time.  The Quest is a pain to repalce the belt and pump.  If you feel you are up to it purchase a Haynes Manual and spend the weekend doing the job.  If you get the cams off just one tooth it will trash the engine.  I would really leave this to a shop unless you have done one before.  You do not want to destroy your engine...  A Haynes Manual is good or a factory service manual can be downloaded at nissantechinfo.com for the cost of $20 bucks an hour.