there is two ways, the 1st is to open the trunk at lowes and take the old one out and dump it in the parking lot and then set the new one in. Although it would have to be a pretty small one to fit in the trunk the other way would be to raise the hood and remove and install a new engine. Since the lumina doesnt have a water heater (except I guess you could call the engine a water heater) but if you actually ment the water pump on the engine or the heater core in the dash I would recommend buying a chiltons shop manual on the car.
Drain the water from your 1993 Chevy Lumina cooling system. Remove the water supply hoses to your heater core. Remove the heater core retaining bolts. Reverse the process to install the new heater core.
Remove the water supply hoses to your 1998 Chevy Lumina heater core. Remove the heater core retaining bolts. Reverse the procedure to install the new heater core.
Remove the belt from your 1994 Chevy Lumina water pump. Remove the water pump return hose. Remove the water pump retaining bolts. Reverse the process to install the new water pump.
Remove the belt from your 1992 Chevy Lumina water pump. Remove the water pump return hose. Remove the water pump retaining bolts. Reverse the process to install your water pump.
Drain the water from your 1990 Chevy Corsica cooling system. Remove the heater core water supply hoses. Remove the heater core retaining bolts. Reverse the process to install the new heater core.
Remove the water supply hoses from your 1985 Chevy heater core. Remove the heater core retaining bolts. The heater core will come out. Reverse the process to install your new heater core.
Drain the water from your 1997 Chevrolet Lumina cooling system. Remove the water supply lines to your heater core. Remove the heater core retaining bolts. Reverse the process to install the new heater core.
Drain the water from your 1983 Chevy Caprice Classic cooling system. Remove the heater core water supply hoses. Remove the heater core retaining bolts. Reverse the process to install the new heater core.
Remove the water supply hoses from your 1992 Chevy S 10 pickup truck heater core. Remove the heater core retaining bolts. Reverse the process to install your new heater core.
Remove the heater core water supply hoses from your 1979 Chevy Corvette. Remove the heater core retaining bolts. Reverse the process to install the new heater core.
The heater core can be found behind the passenger side kick plate. Remove the water supply hoses from your 1996 Chevy Impala heater core. Remove the heater core retaining bolts. Reverse the process to install the new heater core.
It could be coming from your heater core, may need to repair or replace it.