Volkswagen Repair: 2001 VW jetta gl overheating, vw jetta, air pockets

Question
I have a 2001 jetta gl with 135,000 miles,automatic and is overheating. I replaced the thermostat and while the engine is just idling it will not overheat. But when i start driving and not get three blocks it will start overheating. My fans are working great.

Answer
Hi Ryan;
This is one of the most common problems with Volkswagens.  First of all is your water pump OK?  Did you happen to know that while the thermostat was out it was possible to touch the back of the impeller on the water pump, and test it?  Also, I'll bet you didn't know that the cooling system HAS TO BE EVACUATED to a vacuum of 1.8, to 2.0 atmospheres before it can be refilled.  There are air pockets in the cooling system that have to be removed, and there isn't any other way to do it except by using a Volkswagen specific tool, or an "Air Lift" brand evacuation/refilling device.  Without doing this, the car will always overheat.  I'm sorry but this is the only way.  Call the local dealer, and see how much they will cahrge to do it.  Your problem will go away, provided there is a good water pump in the engine.  If the water pump has to be done, then do the timing belt, and tensioner at the same time.  But, always vacuum fill the Volkswagen cooling system!  Sorry, Ryan.  I hope this helps.  Good luck.