I have a 2000 Durango that's constantly overheating. This started a few months back. The coolant is full. I took the top off the hose and filled it with water after flushing the line. I'm replacing the water almost daily. When the truck stops I can hear the water gurgling under the hood, hear a loud whistling, and see steam coming from the hood. I also replaced the hoses.
I've replaced the clutch fan and the plugs. I replaced and then removed the thermostat. (Someone told me that the plugs could be the cause) I don't know what else it could be. I'm sure the radiator is functioning. Now the truck is stuttering and making putt putt sounds. I don't think the heads are blown because it's not cutting off or smoking. The issue is the overheating. Does anyone have any suggestions?

 

Which is it? Is it leaking or not? ...puddles under the truck? Where are the post-ride gurgles coming from? How does the oil look on the dipstick?

 

Knowing the engine would also be useful.

 

Not knowing the engine size makes it very difficult to guess what the problem can be.
The " put put" sounds does sound concerning, like water is going where it shouldn't be. When you pulled the plugs did they look wet? Pull the oil pan dip stick is it milky looking or smells lIke antifreeze? Truck should not be going put put so I am thinking maybe you blew a head gasket or possibly cracked a head. To test that possibility you will need to do a cylinder pump down test ( compression test)

Let's say all above checks out.
When you installed the thermostat did you put it in the right direction? There is a top and bottom. Also ( again engine size helps here, the better thermostats will have a hole in the side of them, this allows the system to burp itself and will save you a headache)
If you are losing water it's going somewhere so you need to check all hoses for leaks when you have the engine running.
Check and see if you have a clogged or cracked heater core.. start the engine warm it to operating temperature (( you want thermostat open so water is flowing. Carefully touch the upper radiator hose and check it its hot, it should be hot. Now look left (( passenger side) and you will see 2 hoses going into the firewall, touch them bare handed (( carefully) if you can ggrab them both and they are cool or Luke war you have a clogged heater core.. You should not be able to touch those bare hands more then a sec or two because they should be that hot..
My experience had been you get better results by flushing the heater core separately ( removing the hoses from the fire wall) one goes from the stat to firewall and the other is the line I have my system flush connector on.. take a garden hose and alternate from one hose to the other.

If you just want to do it all at once
Drain the radiator and take off the hoses. Spray the radiator out with water and remove the T-stat and back flush with the house hose on full blast. Disconnect the reservior hose and spray out the hose and clean out the reservior. Connect the heater core hose and spray out the heater core back and forth between hoses.

The final thing I can think of is the water pump.. if the seal are bad it could leak and cause the steam that you see you will need to look around the water pump area to see if it's been leaking ( sometimes it's easy to see and sometimes not) a quick test to check the water pump is to start the engine and run it up to operating temperature. You may need a extra person to help you rev the engine from inside the car or you can just move the linkage at the throttleody.. grab the upper radiator hose and squeeze, carefully it's hot. Review the engine and you will feel water rushing.. if you feel very little or none at all you have a bad water pump. (( I will post video about how to do additional checks)

If you have a bad water pump you will want to flush the entire system as shown above, you don't want old grime getting into the new pump.