How do you replace the water pump on a 1999 gmc Yukon?

need to know how to take fan off a 97 GMC 1500 truck to replace water pump

I've done this before it's not to tough! Start by removing the plastic fan grad between the engine and radiator. Drain coolant from the radiator, about 2 to 3 gallons, and keep it contained for possible reuse. Note it is a good idea to put some cardboard on the radiator to protect it from damage by wrenches falling, a Pizza box unfolded flat works good. Remove the fan blade by using a big crescent wrench to grab that large hex nut between the fan blade and the water pump; hold on tightly to the fan belt on the pulley of the water pump as you jerk your wrench handle. One spin the fan off. Remove your fan belt- But 1st draw a diagram of the fan belt and how it connects to all the pulleys on the engine so you can put it back on. Unbolt the pulley wheel from the water pump. Put a bucket or pan under the water pump to catch more before you loosen all the bolts that hold it on the block. Once drained and unbolted remove the old pump. Scrape the engine clean at the 2 ports the pump bolts to. Use new gaskets and RTV Silicone glue on both faces of the gaskets. Bolt the new pump on your engine and reassemble all the rest in reverse order. Be sure to get the coolant level back up to Parr and before you go driving dabble check everything and let the engine idle for 10 minuets to check for leaks. Be safe and I hope this did the trick for you!