My 1998 Oldsmobile Aurora, is overheating! I have changed the thermostat, check the radiator, replaced the cooling fan sensor and had a diagnostic done on the head gasket. The car is still overheating!!! What should I do

Try changing radiator cap if there is no water in the oil it is not a head gasket could be system just needs a flush. It could also be the water pump is not pumping well try the cap first.

CHECK COOLANT LEVEL MOST NEWER VECHICLE DONT HAVE RADIATOR CAP YOU HAVE TO POUR COOLANT IN THE COOLANT OVERFLOW JUG THE COOLANT WILL GO TO RADIATOR. IF THE COOLANT OVERFLOW JUG EMPTY ADD COOLANT UNTIL COOLANT LEVEL STOP DROPPING AT STAY AT FULL COLD MARK.IF COOLANT OKAY,NEED TO REPLACE THERMOSTAT AND COOLANT OVERFLOW JUG PRESSURE CAP. IF ALL BEEN DONE. MOST OF THE TIME WHEN CAR OVERHEATING WHILE MOVING. RADIATOR CORES STOPPED UP OR RADIATOR GRILLE DIRTY OR RESRICTED.ENGINE BLOCK COOLANT PASSAGES CLOGGED AND HEATER CORE CLOGGED.CHECK WATER PUMP SEE IF WATER PUMP WEEP HOLE LEAKING IF SO REPLACE WATER PUMP.IF ENGINE OVERHEATING AT A LONG TRAFFIC LINE ENGINE COOLING FANS NOT RUNNING EITHER COOLING FANS FUSE AND RELAYS BAD.OR ENGINE COOLANT TEMPERATURE BAD. THE ENGINE COOLANT TEMPERATURE SENSOR TURNS ON COOLING FANS AT A CERTAIN TEMPERATURE IF SENSOR BAD FANS WONT TURN ON. MAKE SURE YOU HAVE 50 /50 MIXTURE OF COOLANT AND WATER IN COOLING SYSTEM.

Since you replaced the pump, the coolant reservoir probably got empty during the process and sometimes the level sensor inside it tends to get stuck. Look at the reservoir and on the bottom of it there should be some wires coming out of it, that's where the level sensor is. Lightly tap it with a pair of pliers and it should come up therefor removing the low coolant light. Now for the overheating, turn on the car and let it come up to temp, open the hood and make sure your fans come on when they're suppose to. If the temp is going higher and the fans don't come on then you need to check the fan relays or the coolant sensor. Turn on the ac, the condenser fan should start up, see if that helps it cool down. If the radiator fan does not come on, unplug it and plug it straight to the battery to see if it turns on, if not, you need a new fan, if it works then like i said, relays, fuses, sensor. Oh, i almost forgot, replace the THERMOSTAT as well.

that leaves the radiator or the head gasket, do a compression test, look at the plugs for a whitish deposit, sure sign of coolant, good luck

there isa short in the wiring somewhere,which a shop can check for you,or check your thermostat. after 20 years i still have to make sure tat i dont install it upside down. which is easy to do if your in a hurry. my bet is that the wiring going to the coolant sensor has a bare spot and grounding somewhere.

I would check to see if the cooling fan is coming on. Could be a bad fan switch. When the air is turned on, it turns on the cooling fan regardless of engine temp.

You could have several issues here. A blockage in the radiator, bad coolant temp sensor, (not turning the cooling fan on) a bad cooling fan motor. sounds as if maybe one of these may be your primary issue, and the cause of the overheating that originally caused your head gasket problem. Hope this helps

Cause of overheating besides radiators are as follow. Radiator fan. (overheats while stopped). Thermostat. ( overheats all the time).

Check all hoses and belts see if they look ok. then check antifreeze or check for leak at radiator, by doing a pressure leak test also check cap with pressure test. next check thermostat it may not be opening properly. thermostats go bad and they only cost about 10 bucks. good luck.

I had the same problem and tried several things that didn't help. A friend introduced me to a Northstar mech. that explained the real problem. Internal engine relief was faling which created overheating between cylinder sleeves and engine block creating blow back pressure in cooling system. There is a fix for this. The mechanic helped me with the problem and car is running once more... Anyone thinking they have a head gasket, intake gasket, or thermostate problem should look at this fix.