Overheating jetta

I have a 2003 VW Jetta. It overheated and stalled last week. The mechanics tried replacing the thermostat twice, flushed out the entire cooling system, and when they took it for a test drive, it overheated after ten minutes of driving. They are unable to locate the problem. Can someone help me?

Clogged radiator? Cooling fans not working? Water pump not working? Leaking cylinder head gasket?

Did they check any of these?

What, exactly, happens when the engine “overheats?” Does coolant boil out of the radiator or are you just seeing a high reading on the dashboard gauge?

The temp guage registers hot and the car stalls and will not re-start until it is cooled off.

 [i] The temp guage registers hot and the car stalls and will not re-start until it is cooled off. [/i] 

You certainly don't want to continue doing that.  Is it loosing any coolant when this happens?  It really seams odd to me that it would get hot enough to stall without loosing coolant.

There is still coolant in the overflow tank and I don’t see any leaks under the cr.
It seems strange to me that the mechanic can’t find anything wrong. I am so afraid to take it to the VW dealer because they tried to take advantage of me last year.

They didn’t note anything about the color of the coolant when they flushed the system did they?

Could be a bad temperature sensor throwing off the dash gauge and making the ECU shut the engine down.