My 93 FWB with the 5.7 has two lower radiator hoses. What is the purpose of the second one? I need a radiator and all I have found are single outlet radiators. What's up with this? I have another one being delivered in the morning from radiator.com which they say matches the Vin# but no one could tell me if it had the two outlets. Mine has a small one on the driver's side and a larger one on the passenger side. They both go to the same area on the engine.
Not sure if this is the issue or not, but I will give it a shot... Sorry for the long response, didn't see the original post...
Ok, there is 2 large hoses, lower one (non LT1) is suction, and upper one is return. The lower goes to the inlet of the pump, which pumps through the block to the heads, to the thermostat, back to the upper hose. Pretty simple system. Somewhere in the system, typically just before the thermostat, sometimes at the back of the head, there is a heater hose pickup, which feeds the heater core. It must return to a suction side of the system, i.e., the pump directly, or to the side of the radiator that has the lower hose.
Now, in some cases, GM put the heater hose return in the radiator. It shouldn't make much difference, but in the case of my old 76 Olds Delta 88, it was done on the HD Cooling cars. Look to see if you have V03 or V08 cooling. Some of the LT1 Z28's and Trans AM's had this as well.
The radiator hoses are the main hoses, around 2" to 2.5" in diameter. The heater hoses are typically 3/4" to 7/8" in diameter.
The LT1's (94-96 Fleetwoods) had an entirely different cooling system, which isn't discussed here...
Hope that helps and might shed some light. I don't have a 93 car, so I can't look, but if you take pictures, I can give you more insight.
Just remember, general rule of thumb (again, NON LT1) is lower side of any heat exchanger, i.e. radiator, heater core, AC condenser, AC evaporator, is the SUCTION side. This is done to prevent cavitation of the pump when low on fluid. Being cooling system are hot, steam will erupt if air is present. The stock cooling systems rarely have air bleeds, but sometimes do and help remove more air keeping steam to a minimum.