Car runs hot

First make sure that you have the correct radiator cap. The wrong cap or a weak cap will allow too much coolant to enter into the overflow.
Water pumps will sometimes leak when the engine in running and not when it is stopped.
A bad heater core can be leaking and the drain tube is under the firewall and may not be noticed.
Best to use a pressure tester and pump the cooling system to 14 psi and watch for leaks.

radiator hose may be closing together after running for a while causing water to overflow to tank and ground

If the coolant was hot when you noticed water coming out the radiator, that is normal from the heat expansion of the coolant. That is why there are coolant overflow tanks-also called coolant expansion tanks.
When refilling coolant, always top up the radiator, and fill the overflow tank to at least the cold mark level (about half-way up on the tank). With cap off, run engine till the thermostat opens- upper radiator hose will become hot-then shut off engine, add coolant to radiator as needed, replace cap. This method of filling will help to expel any trapped air in the system. Oh, and remember to set your heater controls on high when filling coolant, so the heater core and lines also circulate and expel air.
Check the seal on the radiator cap that it is still good. The cap seal is important to seal the coolant system, as it is a closed system under about 15 psi of pressure. The reason to pressurize the system is that the pressure will raise the boiling point of the coolant by about 10 degrees- important when you consider how hot the coolant has to be when running. OK, enough tutorial-I don't think you have a problem with the water pump! G'd luck, reeve.

replace thermostat.then bleed coolant system, this is how you do it.fill the cooling coolant system with 50 / 50 dexcool and water to raise boiling point,straight water will evaporate boil away cause engine to overheat catch fire thats why you need 50 / 50 mixture antifreeze and water.to bleed coolant system first fill coolant system until coolant stay at the full cold mark on the the coolant overflow jug,then you start engine allow it to idle,place the heater and ac control in any ac setting except max and the temperature control to the highest setting,run engine until lower hose to water pump is hot. with the engine hot run the engine speed up to 3000 rpm and allow it return to idle, repeat this 5 times. slowly open the bleed valve on the thermostat housing or look for bleed valve at the water pump heater hose.open bleed valve for 15 seconds to expel any trapped air.then top off the coolant as necessary,and when top radiator hose hot thermostat open up.keep adding cooling to overflow until coolant level stop at full cold mark dont over fill coolant.if engine seem like overheating while looking at cooling gauge turn off engine wait a while until cool off add more coolant until coolant level stay stable and dont drop any.when open radiator overflow cap use large rag over the radiator cap to keep from getting scald open radiator cap a little at a time but dont open radiator cap until engine cool down first.replace the radiator overflow cap, thermostat,and engine coolant temperature sensor and check the cooling fans fuses and relays see what happens.

Sounds like there is air trapped in the system. On a COLD engine, remove the radiator cap, and check the level. If it's low, slowly add coolant until the rad is filled right to the top, then cap it. Top up coolant overflow bottle if required. Start the engine. As the engine reaches operating temperature, the coolant level in the overflow bottle should rise. If it doesn't, it means that all the air is not yet 'burped' out of the system. Provided that the radiator cap is good, and that the coolant level is maintained at the proper level, the system should eventually expel all the air. Hope this helps. Good luck.

REPLACE THE THERMOSTAT AND RADIATOR PRESSURE CAP.IF COOLANT LOW, ADD MORE COOLANT THROUGH COOLANT OVERFLOW UNTIL COOLANT LEVEL IN THE COOLANT OVERFLOW STAY AT FULL COLD MARK.REASON POUR COOLANT THROUGH COOLANT OVERFLOW MOST GM CARS DONT HAVE RADIATOR CAP.WHEN YOU GET COOLANT LEVEL OKAY, CRANK CAR LET IT IDLE UNTIL ENGINE GET HOT BUILD UP PRESSURE THEN TURN OFF CAR.CHECK FOR COOLANTS LEAKS AT THE RADIATOR HOSES,CHECK FOR LEAKS AT THE RADIATOR, CHECK FOR LEAKS AT WATER PUMP WEEP HOLE IF YOU SEE COOLANT LEAKING FROM WEEP HOLE REPLACE WATER PUMP. IF CAR OVERHEATING WHILE IDLING YOUR COOLING FANS NOT WORKING CHECK COOLING FANS FUSE AND RELAYS.IF FUSE AND RELAYS OKAY THE ENGINECOOLANT TEMPERATURE SENSOR BAD.

DID YOU BLEED AIR OUT THE COOLANT SYSTEM.TO BLEED COOLANT SYSTEM, FILL THE COOLANT SYSTEM THROUGH THE RESERVOIR TANK OR THE RADIATOR UNTIL THE FULL COLD MARK IS REACHED.BESURE TO USE 50/50 HALF WATER AND ANTIFREEZE.YOU CAN BUY ANTIFREEZE THAT IS ALREADY PREMIX 50/50.AFTER ADDING ANTIFREEZE TO RESERVOIR OR RADIATOR FILL RADIATOR TO FULL MARK OR IF YOU DONT HAVE RADIATOR CAP ON RADIATOR POUR ANTIFREEZE IN THE OVERFLOW JUG UNTIL COOLANT LEVEL STAY THE FULL COLD MARK.WAIT AWHILE UNTIL COOLANT LEVEL STOP DROPPING.NOW INSTALL THE RADIATOR OR OVER FLOW JUG CAP.START THE ENGINE AND ALLOW IT TO RUN UNTIL NORMAL OPERATING TEMPERATURE IS REACHED AND THE UPPER RADIATOR HOSE BECOME HOT.STOP THE ENGINE AND OBSERVE THE COOLANT LEVEL IN THE OVERFLOW JUG. THE COOLANT LEVEL SHOULD BE AT THE FULL HOT LINE.ALLOW THE ENGINE TO COOL UNTIL THE AMBIENT TEMPERATURE IS REACHED THEN CHECK THE COOLANT LEVEL IT SHOULD BE AT OR ABOVE THE FULL COLD LINE.ADD MORE COOLANT IF NECESSARY. WARNING BECAREFUL WHEN OPEN THE RADIATOR CAP OR JUG OVER FLOW CAP.USE A LARGE RAG OVER THE RADIATOR CAP TO KEEP FROM GETTING SCALDED.OPEN RADIATOR CAP A LITTLE AT A TIME TO KEEP FROM GETTING SCALDED.WAIT UNTIL ENGINE COOL DOWN BEFORE OPENING RADIATOR CAP OR OVERFLOW JUG CAP.WEAR SAFETY GLASSES.

To see if it is your water pump - remove the radiator cap and start your vehicle while it is cold. the water should not circulate due to the thermostat being closed. When it is warm, the coolant should be seen to ciculate as viewed through the rad cap opening. (be sure there is lots of coolant - of course) Also if there is no thermostat - the water will circulate after the engine is started wheather hot or cold if the water pump is working. You say it is a new thermostat so I assume it is not stuck closed.

Overheating can be numerous things: Fans not working, water pump, thermostat, overflow cap, and the list keeps going. When the engine is running and heats ups, feel the heat of the top hose, if the hose isn't hot, the thermostat is most likely stuck open and needs replaced. If it is hot we know you have circulation. The cap on the expansion tank may be defective, if it can't hold the pressure of the water, it will release at the overflow cap if the cap is bad. Also check the coolant level.

The best way to flush it would be to take off the bottom radiator hose and pump water through the fill nozzle after all the coolent is out you can then hook the hose back up and replace it with new coolant.