Hi, I own a 1995 Oldsmobile Aurora, it has that monster Northstar v8 engine. First, the car started to overheat, I thought maybe it was the Thermostat, changed the thermostat, wasn't it. Next, I changed the water pump, that wasn't it, still overheats. The radiator is fine, no problems with that. My next guess is the Coolant Temp Sensor, I am planning on replacing this part. Do you think that replacing this part would fix the overheating issue?
Also, recently, the car has been running kind of sluggish. When I take off, it feels like the car struggles to accelerate at first but once it gets past that part it runs normal and then you can feel like it skips, I don't really know how to explain it. What can I do to fix the overheating and the sluggish feeling? Thanks for any input.
Answer: As long as there are no air pockets from the above repairs from not properly bleeding the cooling system, then these conditions, along with the repairs already made, make me think you have head gasket problems. This Northstar engine was know for having head gasket problems causing overheating. Sometimes the gasket forces compression gasses into the cooling system, causing air pockets. The air pockets cause overheating, and the no heater from heater. The running sluggish could be a bad plug wire, spark plug or ignition coil. See this link for inspecting spark plugs and ignition coils.