I've had this happen to me before. I had the water pump replaced after it had been leaking a little and my car overheated. We thought it might have been leaking again but turns out the mechanics had forgot to tighten something. I would have them look at it once more to make sure nothing is loose and leaking your coolant.
Bad thermostat maybe?
If your radiator isnt leaking and car is having a over heating problem and coolant spewing out. Chances are your thermostat needs replaced. possible the radiator needs to be flushed. But more likley its thermostat
You need to replace the thermostat and flush the system of crud.
Either: 1) Thermostat is bad or 2) Radiator is clogged or 3) if your losing fluid or hearing a noise, check your water pump. If your not losing fluid or hearing a noise, the service the radiator by having it flushed. If this doesn't solve your problem, then change the thermostat. If your still having the problem then your radiator may need further service or even replacing. I'm having the same issue right now. I'm replacing my thermostat next. If it still is running hot, I'm going to take the radiator out and have it serviced. Good luck! And remember, DONT let the temperature get in the red!!
So far you've done all the right things. Have you considered also having the radiator flushed? Have you replaced the hoses? As the hoses age, they get soft and can collapse when under suction by a properly operating water pump.
Bottom of the engine where the lower radiator hose connects. Besides having to lay on the floor, it is easy to replace.
I was having the same problem with my car. When you take the thermostat out it will automatically read cool. But I later found out that I had a leak in my radiator and had to replace it. Turned out that my heads are warped and was leaking oil into my water and into the radiator itself. Once i replaced the radiator its been fine.
Find and disconnect the upper radiator hose. This will be a hose going from the top of the radiator to the top of the engine block somewhere. The upper radiator hose attaches to the thermostat housing, which is usually secured by 2 or 4 bolts. The thermostat is inside and you will probably need a pick to get it out. Having said that, your thermostat probably isn't the problem if you are overheating. GM motors have really bad intake gasket design, which can cause your car to leak coolant, which will in turn cause it to overheat.
follow the top radiator hose to the engine
follow your lower radiator hose from radiator to engine block ----- thermostat is inside plastic looking housing that bolts with 3 bolts there ----- comes as complete unit (thermostat & housing) from manufacturer and aftermarket as far as I know and runs around 150.00 ----- having cooling problems with my 01 2.3 now and just replaced it
Engine overheats When a car or truck overheats idling, in town, on the highway, while towing, etc. it is important to find out the reason to prevent engine damage. First, with the engine cold, make sure the radiator is full of coolant; if it is low, fill it and keep the radiator cap off while the engine idles to insure all air is bled out of the system ( air trapped in the system can cause overheating also). Check the coolant level daily; if the coolant goes down without visible leaks, it may be a head gasket starting to leak which will also cause the heater to blow cold air due to the lack of available coolant. If the coolant stays full, but the car continues to overheat, the next step is to replace the thermostat in the engine and flush the cooling system if that has not been done over the last few years.Buy a thermostat at a parts store and a PRESTONE flush kit which has excellent directions on the package.After completing these steps and the vehicle still overheats, have your cooling fan sensor/switch ( if equipped)checked out to insure it is coming on. Water pumps are seldom the cause as they are mechanical and will continue to work until their bearings give out. Finally, the radiator itself is often the problem as it tends to build up corrosion internally which prevents it from transfering engine heat to the coolant. Remove it and have it 're-cored'. One of these steps will solve the problem.
the water pump is right behind the radiator and is belt driven. Also try to check the coolant reservoir by having it pressure tested