I have a 1999 Oldsmobile Alero with a 3.4 liter engine I believe. The cars catylst decal states a 3.4, and service manual shows a 3.4 as the only v6 option for a 99 Alero. However the upper intake manifold does have 3100 cast into the top of it. Anyways the car is overheating, and I have no heat in the cab when heater control is set to heat. have replaced thermostate, also made sure blend door actuator motor is working. pressure tested the cooling system over night and it dropped 2 psi. Not too worried about a 2psi drop overnight. Have not observed any external leaks. I have flushed water through the heater core, radiator, and engine. Have observed ther the t-state is opening as outlet rad hose is getting hot. the heater hoses are not getting warm. Did remove and inspect water pump, found no casue for concern. After last test drive had steam coming out surge tank overflow, and hooked up scan tool and found engine to be at 250 degrees. Also verified with Raytec temp gun. Was thinking of doing a cylinder leakage test next. Looking for any other thoughts.