Engine is Overheating?

Engine Cooling problem
2003 Buick Rendezvous Automatic

I have replaced the intake gasket, wires, and thermostat but my truck is still overheating.

Engine Cooling problem
2002 Buick Rendezvous 140, 00 miles

My car was running hot so I took it to a mechanic. He said it was a cracked head. He fixed it and some other stuff and I ended up paying $2,500.00. I have had it back for about a week and my radiator is still boiling but my gauge will go all the way to cold, and my service engine soon light will come on, then go off, then come on again.I had the thermostat changed 3 times in two weeks. What do you think it could be?

Parked the car to look at a map for about a couple of minutes 2 days ago, the temperature hand went to the very end in the red area. Turned off the engine for a couple of minutes, & restarted. Now the temperature hand goes left and right of the center mark during driving, and goes to overheat area during traffic stop and parking. What could be the problem?

Thanks Guys,

I havn't checked the cooland tank for a while, and found that it's empty. So I added some Dex-Cool, and it seems working fine now.

By the way, I checked the owner's manual in that section, and it mentions a "Full Mark" on the tank, but I didn't see such mark. What did I miss?

Again, appreciate your input.

Have a great day!

I have a buick rendezvous 2002. About a week ago I noticed my car started kicking out cold heat and my temperature gage started to rise abnormally. Now it only kicks out cold ish air and my temperature gauge will jump between the first line to even the red line

The coolant level is fine. I have had a new water pump, thermostat, and blower motor resistor put on. I had the blower motor resistor put on to fix my heater controls, because it only worked on numbers 4 and 5. But never had any issues with cold air or over heating until a week ago.

I need help. I have no idea. It's almost like something is clogged or the water isn't getting to the engine.

My car keeps overheating and the fans are not turning on. We replaced the relays and the Temperature Sensor which did not help. When we disconnect the Temp. Sensor the fans engage. Any ideas please?

Temperature spiked to maximum hot after driving with heat on max for just over 1 mile. Turned heat down to cold and the temp went down a to just above half way mark to 3/4. The vehicle is a 2002 Buick Rendezvous CL. Do you think this is thermostat or something more serious like heater core?