Brand new rad, all hoses and connections are good, car still overheats, water running underneath the engine, what is going on?

THE COOLANT SYSTEM ON MOST CARS ARE VERY COMPLEX,. NOT IN THEORY EVER, BUT IN PRACTICES SO MANY PLACES TO LEAK.
1996 NO VIN TOLD OR WHAT ENGINE IS THERE,.

USA CAR HAD 2.
3.3 L EGA V6
3.5 L EGE V6

FEW USEFUL FACTS TOLD. JUST LEAKS.
THERE ARE 2 WAYS TO FIND IT AND YOU DID NONE.(i SAY STOP GUESSING, (BUT CAP AND THERMOSTAT ARE SLAM DUNKS.)
1: HOT ENGINE TEST, HAS 15PSI UNDER THE CAP
AND ANY LEAKS , HOOD UP IS SEEN CLEAR AS DAY EVEN SQUIRTS 3 FEET AWAY FOOLING YOU.
DO NOT DRIVE THE CAR AND BLOW WATER ALL OVER THE ENGINE BAY OR OVER HEAT IT.

NOT TOLD IS COOLANT ON THE GROUND OR IN THE OIL PAN OR ON PASSENGERS FOOT WELL OR TOES.OUCH.
2; USE AND READ LEAK DOWN PRESSURE TOOL.
DONE COLD. ENGINE AND 10 X MORE SAFE BUT THE TOOL COSTS MONEY TO BE SAFER.

#1 TOLD AGAIN BY ME HERE VAST TIMES.
FIRST GET THE Rad FULL.
NEW GAS CAP $5
NO 27 YEAR OLD THERMOSTAT IS GOOD. EVER.
7 YEAR EOL DESIGN LIFE SPAN IS SPEC. SO ....A>>>>>$25 FIX, AND NO CAR FIX IS FREE..
(ASIDE OF LOSE CLAMPS)

KEYOFF COLD ,RAD, ADD 50% AF FLUID FULL
i USE "PRESTONE ANY CAR" AF FLUID TODAY.
ZERO MIX ISSUEA WITH OTHER BRANDS !!!!!!!!
OK RAD IS FULL. FOR SURE.

HOOD UP. ENGINE COLD
KEY ON START IT FOR UP TO 30 MINS.
GET ENGINE FULLY HOT,. NO NOT BOILING
KEY OFF IF IT OVERHEATS TOO SOON
KEY OFF NOW. i USE SCAN TOOL AND SEE PID ECT AT 180F+ NOW AND SAY OK THIS BLOCK IS NOW FULLY HOT. (NORMAL)
THE CAP NOW IS AT 15-PSI AND IN FACT
ANY LEAKS THERE ARE MOSTLY ARE SEEN NOW
IF YOU GO SLOW AND JUST LOOK.
THE HOSES ALL
THE WHOLE ENGINE CAN LEAK
WATER PUMP
HEADS TO BLOCK LEAKS(HEAD GASKETS0
IF V6/8 ENGINE, NONE TOLD CAN LIKE AT INTAKE MANIFOLD FRONT OR REAR (PUSH ROD ENGINES NOT OVERHEAD CAM ENGINES
WATER IN TO THE ENGINE OIL PAN OR THE TRANNY.
WATER TO PASSENGER FEET HEATER CORE BAD.
LEADS TO GROUND ARE EASY TO FIND, LOOKING
TO OIL PANS WE SEE LUBE AS CHOCOLATE MILK.
THE FRONT OF MY 3.7 LITER , THE FRONT COVER OF ENGINE, HAS WATER PATHS. THAT SURE CAN LEAK.
THE CAR RUNNING WATER FOR COOLANT
AND IT FREEZES OUT SIDE AT JUST BELOW 32F
THE ENGINE CRACKS IN HALF.
CRACKED BLOCK AND OR HEADS.
DOOMED, SO NEVER JUST WATER
ONLY RUN 50% AF ONLY
THE TRICK IS WATCH IT LEAK HOOD UP.
HURRY NOT.
YOU WILL SEE IT OR IS A HUGE PROBLEM.
OR IS HEATER CORE LEAKING
OR SEE RAD LEAK LIKE MAD.
FIND THE LEAK PARKED IS BEST.
GOOD LUCK !!!

Could be that the heater core is clogged... for the car to operate at optimal temperature (not to cold, not too hot) all cooking system had to be working properly, I had a '97 camaro, it had 2 previous owners and I had heater core issues and also the hose that goes to the expansion tank was clogged, causing the water to build enough pressure to escape trough radiator cap... anyways they're two totally different cars but seems to me you need a cooling system flush.

They sell a kit which includes a T fitting that goes in the hose flowing towards the heating core, and allows you to connect a garden hose to push water through the system with radiator cap off so all can circulate and clean up. Being careful (water pressure in houses is more than the system is designed to withstand, for instance a radiator cap can be 15 - 20 psi, depending on area, some homes have above 40 psi) is a great diy little project. Alternatively you can pay a mechanic shop to do it. After a flush, drain the radiator from bottom plug and refill with coolant always. Don't run your system with water and don't drive an overheating car, it will blow a gasket and that's when you kiss your car goodbye, repair is not only expensive but blown gasket might leave sequels on engine.

If the t/stat fails in the closed position an overheat will result. I have had a brand new one fail a week after I put it it. Rare but does happen. Have you checked the rad hose, is it warm, hot, or cold during the overheat condition? Is the coolant actually flowing through the system? When its cold (after sitting overnight) remove the rad cap, look at the fluid level...normal? If so start the car and let it run with the cap off..feel the rad hose soon as it starts to get hot look in the rad (be careful if your system has a vapor lock it may spit the air out, best to have a face shield on just in case!)..is the coolant flowing? It should start flowing at some point. If not the t/stat is stuck closed or the water pump is broken/seized.

Check hand brake is fully released. Why head gasket had been ruled out ? Run engine till warm, carefully open rad cap, let engine idle, look for BUBBLES IN COOLANT. IF YOU SEE ANY NO MATTER HOW SMALL, CHANGE HEAD GASKET.

Fill the rad or overflow bottle right to the top and run the engine with no cap on,if you see a constant flow of bubbles your head gasket is leaking or you have a crack somewhere in the cooling system.

unclip topmost hot hose when engine is running to vent any airlock.
have you checked fan rotation......?

Probably not water pump. Engine is notourious for vapour lock.
Cooling system must be blead of air before thermostat will work. Cool bottom rad hose is a dead give away. If you are still watching this forum reply , and I will walk you through the only way I know how to make it work properly. It's actually easy if you do it my way. I have worked on lots of cars , and this engine was the hardest to bleed out. Did one Yesterday , and works perfect.

If you see no leaks and the fluid level is also good in the rad overflow bottle. It could be the water pump. When the car is running do you feel the hoses are hot and pressurized. Do you feel heat with your heater cranked up. The coolant may not be circulating. This would mean you need a new water pump, most likely the impeller is worn/broken inside. It can be fixed by yourself but will require some skill and time.

the black chunks could possibly be from someone putting a stop leak solution into the radiator first drain the coolant system fill up with clean water put in some Prestone 10 minute flush and then drain and put in a flush tee in the heater hose not the one going to the water pump but the one going to the engine block open up the drain hose and run water through until clear and refill with new antifreeze and make sure car runs until all air bubbles are out and then replace the cap

turn your heater on to max heat and high fan. then see if you can feel the hoses on the firewall for heat they should be hot. make sure that the fan unit on the radiatoris working if the upper radiator hose is hot the fans should be running if they are not that means that either the relay is bad the thermo sensor is bad or the fan unit is shot... please rate the solution..........thanks