My Jetta is overheating even after thermostat change!

I drive a 2003 VW Jetta Wagon 2.0l auto. I thought that my car was overheating so I changed my thermostat. Low and behold no change still overheats. Here are the symptoms: Turn on car on idle does not overheat! Drive car rpm rev car overheats. I noticed something strange with my heat in the car. It does not work. So new thermostat no heat maybe the water is not moving? I don’t know what to think. The car has 80K on it. Could it be time for a new water pump? Because I don’t know what else could be wrong. Please help me with my dillema. Thank You.

Well it may be time for a new water pump, but there are sstilll lots of other possibilities.

You say it overheats. Why do you say it over heats? Are you looking at the gauge? Maybe the sensor or gauge is off.

An experience mechanic can rule out many possible problems in just a couple of minutes by looking and feeling hoses radiator etc. Do you have a local mechanic in your area that you trust. (I would avoid most dealers) Has the cooling system ever been serviced? I believe the coolant should have been changed by now. Was the pprescribed VW coolant used.

not to ask a really dumb question, but… are you certain you installed the new thermostat in the correct direction???

the block may be air bound though, which could throw off other diagnostics. i think there is a small plug above (nearby) the water pump housing which you can remove to let any air out.

one way to totally eliminate the thermostat as the problem is to REMOVE the thermostat from the housing and reassemble, and run the car for a little while. if the water pump is shot, then that will show NO circulation, which would mean no water pump.

by any chance have you noticed any antifreeze under the car recently? a drip at the water pump is an indication of a failing water pump. (the bearings going make the seal leak before it totally goes out.)

I did run the car without the thermostat and water is still boiling in both radiator hoses. What else could it be? I am pretty sure that its the water pump. I scheduled a water pump, timing belt drive belt and tensioner change. The car did smell a little bit like antifreeze during the summer so that must of been the bearing leaking on the water pump. I checked and there are no air bubbles in the system. Thank you for the help. If you think that it might be something else please let me know.

An obstrubtion somewhere??? radiator??

I would vote water pump. For gosh sakes, fix the overheating before it warps your heads. My old Jetta did that and I think I spent $800.00 at a cheap shop for the replacement back then.