I replaced the thermostat and found that the copper part of the thermostat had broken of and is in the waterways of the engine somewhere and when you drive about 5 miles it overheats and cuts out, could it be that the part of the thermostat is stopping the water pump

might be simple radiator cap need replace,or a blockage in waterways try flushing them ,if not get it pressure tested .

Go to youtube.com to see a video of this. Usually a simple job, but make sure you get the thermostat in right with the copper pellet side toward the engine.
Main problem people have in general is they let the thermostat slip down out of place and tighten it up, breaking the thermostat housing.
Do the job cold, a hot engine only lends to making mistakes. don-ohio (:^)

Thermostat housing was replaced but the actual thermostat was replaced also?
If it was replaced you might have issues with the water pump, the impellers of the water pump are made of plastic and some of them might be broken.
Also when the thermostat housing was replaced was all the air purged from the cooling circuit?
Air still trapped inside cooling system can create overheating issues.
Never go over 50/50 coolant mix, a higher concentration of coolant can impede a proper engine cooling.

A thermostat is mostly a bimetallic part that will open the waterway from the radiator to the engine block when the temperature is high enough. This has nothing to do with the hose. However, if the hose is swollen then I'd suggest you change it asap as it sounds like it's about ready to burst.

Just a couple things to mention here

1. Is the thermostat in correctly? Don't take this wrong, but I've seen people put them in backwards, so just make sure the copper pellet is on the engine side
2. Is there air trapped behind the thermostat? If hot coolant cannot get to the copper pellet, the thermostat will not open even though the engine gets hot. Ensure the engine coolant has had the air bled from the system.
3. Is the water pump spinning? In the right direction? In other words, check the belt routing

Hope this helps

where is it located....thermostat

If you replaced the thermostat and it gets hotter now, make sure the thermostat is rated at the correct
temperature for your size engine, and also make sure that the long copper element goes into the engine, some times these thermostats will seat both ways, but need to be installed only one way
with the copper element into the engine, so that when it reaches its temperature peak it will open and
allow the radiator water to circulate thru the engine. good luck!

What kind of spark plugs did you use??? Here is a list of plugs that you can use on your Turbo engine.

Champion
* Copper - stock # 440 - RE14MCC5 (OEM)
* Copper - stock # 470 - RE14MCC5 (supercedes/replaces # 440, but some catalogs same part #)
* Copper - RE16MC (supercedes/replaces RE14MCC5 and new Chrysler recommended gap is .040)

NGK
* Copper - LZTR4A-11 (supercedes/replaces RE14MCC5 and new * Chrysler recommended gap is .040)
* Copper - stock # 4306 - LZTR5A-13 (one range colder)

If you use the platinum spark plugs used on the Non-turbo engine, they will start to glow and cause misfires and can cause engine damage to saver detonations throughout the RPM cycle.

As for the over heating, you could have a blown head gasket from a severer detonation if you notice coolant and oil mixing in your engine and coolant tank. The less cause for over heating wold be a bad thermostat or a faulty radiator cooling fan, cooling fan relay or cooling fuse which is located in the engine compartment fuse box by the battery.

Good luck and thank you for using Fixya.

Is the blower blowing? if not could be a blown fuse or bad blower. If the blower is working make sure your coolant level is full, If both of theese things check out , you may have a vacume line loose somewhere that controls the duct witch controls it to change to defrost ,vent or hot to cold.

27th Nov 2007, 15:49 To the above comment: You can't have a 2003 Leganza, because Daewoo stopped selling cars in N. America after the 2002 model year.
A non-operating heater could result from a thermostat that is stuck open, keeping the engine from getting up to normal operating temperature; but if that was happening then you would probably have a check engine light on too.
More likely you have either a stuck or broken temperature control for the heater. Temperature controls are either cable-, or vacuum-operated. Find yours in the heater hose somewhere and see whether you can move the linkage on it. If that causes the heater to work, then you have found your problem. If not, then you may have a clogged heater core, which would probably mean replacement (much more expensive than a thermostat replacement, unfortunately).
Btw, your mechanic does not sound too interested in figuring out what the problem is.