On2003kia sorento changed upper heater hose drove8mi. cameo UT next day coolant running down curb.under front bumper now.why?

You should be able to figure it out. It's only two hoses. Think inlet and outlet to the heater core under the dash. The inlet always comes from upper part of engine, where the coolant is the warmest and where it heats up first. The fitting will come from upper part of intake manifold or the cylinder head. then the hose goes to the firewall.
The outlet from the heater core carries coolant back to the engine and almost always to the water pump on the front of the engine. Makes sense, coolant goes back into the water pump and is circulated again back into the engine.

Disconnect upper and lower radiator hoses while vehicle running. Insert water hose on upper hose and let it run water until you no longer see coolant coming out. Remember to have heaters running to also clean heater core.
Once clear water comes out of lower hose, turn vehicle off and re-attach both hoses. Fill with proper coolant and run vehicle with heaters on. Take for a drive to remove any air from system. Then top off with coolant.

Hi Kevin.

The general route of coolant will be the engine block, the heater core in/near the dashboard, the radiator, and, often, a coolant overflow reservoir that buffers you from leaks if your coolant gets extra hot or bubbly.

So, along with the heater hoses, there are the radiator hoses, either end. Hose connections to the block. Hose to wherever your coolant check/refill container is. The drain plug at the bottom of the radiator.

There is one other place that coolant can go, though you gotta hope this isn't it. If your head gasket is on it's last legs, coolant can start leaking into your cylinder head. This can show up overtly as white smoke, not so smooth running, or mysterious random moments where a hose suddenly bursts or pops loose. Or it can just be an occasional pinhole leak that's hard to detect.

One of the biggest tells - park the car on a flat smooth surface overnight after you've driven it a while. When you come out the next day, is there coolant on the ground anywhere. if yes, the location can help you track it. if no, then exit through the cylinder head may be the culprit. You'd want to run a compression check to make sure, and then contemplate whether fixing it is worth it on a twelve year old car.

Good Luck!

Your radiator has got a damage. For a short term you can use liquid rad seal; but is to be repaired/replaced. When engine/coolant temp is rising volume/pressure is rising too, excess usually goes to expanding canister, but since there's a hole in rad, it gets spewed out.

You'll have to jack up the front of the car, or safer yet, park the car facing up a large hill, and run the car with the overflow cap off while shaking it back and forth. It will take 5-10 minutes but you will get a lot of air out, after this add coolant and drive around, you heater should work better. This may have to be done multiple times to completely purge the system of air.

OVERHEATING

Physically look in the radiator under the cap(if one exsist's) when cool, for coolant level, and check the valve in the cap for sticking. If air is present in the radiator it can't get out, and more coolant can't get in,(from the overflow). Either clean the cap or replace it and check that it is the CORRECT cap.

If radiator is low on coolant fill it to overflowing, replace cap, and check that coolant overflow is filled to the COLD line or mark. The overflow is normally where you would add coolant. (never overfill the overflow)After refilling as outlined above, check the level every morning for 2 or 3 days until coolant level stops dropping below the cold mark and add coolant to the overflow ONLY. Do not open the radiator cap. Also, if you have even a tiny coolant leak anywhere in the system, air will get drawn in, instead of coolant from the overflow.

For more OVERHEATING PROBLEMS try these...
Radiator fins dirty, clean with a strong stream of water, not high pressure water.
Radiator clogged, try backflushing it, or replace.
Thermostat stuck open or shut, replace it. Or installed BACKWARDS.
Water pump worn out, can no longer move enough coolant, replace it.
Fan shroud broken or missing....
Electric Fan(s) not working, Check the fan, relay, fuse and engine temperature sensor's.
Belt driven fan, belt slipping, fan clutch is bad, fan blades have flattened out.
Air dam under front bumper is gone, loose, or broken. It actually has a purpose other than scraping on the driveway or curbs. It forces air up into and thru the condenser and radiator. If it's loose, airflow can actually push it out of place making it useless or blocking the airflow. Along with that, there may also be a plastic piece attached to the bottom of, and wraps up behind the bumper. If it's loose, airflow can actually push it out of place blocking the airflow. Simply reattach it with 4 or 5 screws.

Also, if the vehicle has A/C and electric fans, one fan is dedicated to the A/C and should come on almost the instant the A/C is turned on. The engine fan will run even with the key off, that is normal. The system is trying to cool itself. Hope this helps.

Probability 1) The thermostat is probably stuck open, coolant is not getting hot enough from the engine to provide heat.

Starting from cold, allow the engine to run and warm up. While doing this, feel the upper radiator hose - you should be able to feel the coolant heating up to the point the hose is uncomfortably hot. If it gets that hot, then go to next step.

Probability 2) The heater core flow is restricted, not allowing full flow of coolant into passenger compartment.

There are 2 smaller heater hoses that run to the firewall. Are either of these hoses getting hot? Both sides hot indicate full coolant flow. Both sides cool indicate heater control valve not opening fully.

You may have air in the system. Run the car with the cap removed and the defrosters on allowing air to escape. Add antifreeze as needed to keep full while running. Fluid level will drop as thermostat opens.

This is how I like to do it. Make sure the car is parked with the front end at an upward angle. Drain the coolant from the petcock at the bottom of the radiator. Remove the upper and lower hoses at the radiator. Remove the thermostat housing, and the heater core hoses at the fire wall. Flush out the radiator by pouring fresh water into the overflow, and the hole where the thermostat was. Flush the heater core as best you can by pouring fresh water into the heater core hose connections.
Let all the water drain out, then button everything back up and replace the thermostat with a new one. Refill the rad and engine by filling the coolant reservoir with a mix of 50% water and 50% antifreeze, or buy the premixed stuff from the auto parts store. (Buy 4 jugs of premix or 2 of straight antifreeze)
Run the engine until it reaches operating temperature and the upper rad hose gets hot. Rev the engine a little to help get the air out of the cooling system. When the thermostat opens, the coolant level will drop in the reservoir, so top it up and replace the cap.
Check for leaks, and check the coolant level for the next few days, and check for leaks.
Dispose of the old coolant responsibly

with my experiance on these engines it's usually the upper outlet hoses running from the heads into a t then into the upper radiator hose they are pain to replace but 3 out of 3 of my v6 isuzu's have had the same problem you'll have to pull off the theromstat and the coil pack the hoses are very small and run from the end of the heads one on each into a t then into the radiator hose just under the housing