I have replaced my water pump and viscous clutch on my 6.2 '93 hummer. You do not have to remove any cowling/radiator(s) and to do so does not help. The only problem is the first 4 hex bolts (forward facing) in the fan/clutch assembly. Use a six point box end hex wrench (deep recess) to loosen these first four bolts with the fan belts still attached. You may still need to use a lever or strap wrench to prevent the fan pulley from turning while removing these bolts. Discard these bolts and washers since you will purchase a GM water pump replacement STUD kit from any auto parts place and you will use studs and nuts to reassemble. This allows you to hang the fan/clutch assembly prior to starting the nuts+washers on the stud ends. Since you are using no more than 4 of 5 pulley V's on the pulley you may also plasma cut, then grind smooth the last pulley ridge (be sure to rebalance by suspending on a small wire). Modifying the pulley in this way makes subsequent water pump service much easier. In addition to this first maneuver, you must remove from brackets and tie aside -1- the A/C, -2- the power steering pump and -3- the alternator. This gives you room to operate. Then remove the power steering brackets and studs and A/C brackets. Also make room by poking part of the fan forward into the cowling space. The fan and clutch is removed as a unit and the clutch can be removed from the fan and replaced while working on a table. Please replace the vicious (yes vicious) clutch since its seal life service will not exceed to water pump seal by much and you don't want to do this crap very often (also get new hoses and get new stud bolts and new thermostat (check the new thermostat temp prior to installing)). But wait there's more, aside from the above points you should follow the service manual in regards to actual water pump replacement - it is mounted to the front engine plate by 13? or so bolts and studs and once liberally gunked and tapped off the actual water pump is replaced on the engine plate while the whole assembly is on a table (13? or so more bolts -forward facing). There is a gasket on the water pump to plate interface and plate to engine interface; use a non hardening hi temp gasket sealant. Torque to specs. Blow out most engine coolant before reassembly.

Jan