I have a 2003 Monte Carlo LS 3.4. I have tried everything to make the car run cooler.
The problem, the temp is at half in town, on the interstate for 20 minutes it climbs to 3/4. I'm afraid it will get even hotter. I do live in FL but the temp never used to get that hot. I'm afraid of this engine blowing too.

I started noticing the problem a couple months ago. I recent had the catalytic converter replaced. Shortly after that the rocker arm studs for cylinder 4 completely pulled out of the head, and I lost compression in that cylinder. I put a low mileage engine in the car, less than 47k miles on it.
Still has the same problem. I have changed the thermastat, water pump, temp sensor, radiator, the radiator cap, and all the hoses, fan relays (fans appear to be working properly). Had the system rechecked and the catalytic converter seems to be flowing properly.

Someone please help me!!!!!!! I'm tired of spending money on this car.

 

Check the coolant level in the radiator after parking over night
Might also be thermostat stuck closed.
Checked the oil dip stick make sure it's not mixing oil and coolant (should be brown or black oil not milky/creamy color)
When you drive the car on highway does the temp drop at all or no?

 

Oh also after running the car and driving it for more than 30 minutes, right after you turn the engine off go and bleed the coolant system you will need a 7mm socket for the bleeder screws (two of them one behind the radiator cap and one right infront of the thermostat housing) and open slowly... Does it hiss out air or does it spit out coolant. If it hisses it's and air pocket stuck in coolant system if it spits out coolant right away its a as it should be.

 

Thanks for your reply. The car runs normal temp in town. It only climbs to 3/4 when on the highway. As soon as I slow down from 70 to 45 the temp starts coming down. I replaced the thermostat. Coolant is full, I bled the air out of the bleeder. Still has the problem. Oil looks nice and clean. Coolant looks clean. Still no luck.

 

Did you do any exterior modification to the front grill or maybe your front air damn is missing under the front of you Monte?

 

Finally!!! A solution!!!! I purchased the car near winter time last year. So it hasn't been too terribly hot until recenty when i started experiencing all the problems. When i purchased the car it had no spoiler under the radiator support. The previuous owner probably knocked it loose, and took it off because they assumed it did not need. It. The car had no signs of ever having a spoiler other than a faint line where one used to be. I took one off of a wrecked impala that we had out back. I bolted it on, and now the temp stays below the half way point. I can see that the spoiler causes more air to flow in the radiator, and sends air between the radiator and condenser. Problem solved finally! Drove it 2 hours on the interstate, stayed below half the whole way. THANKS KCFITZ78