so, i'm having trouble with my passat. i've changed the thermostat twice and still no luck. i googled troubleshooting problems with volkswagen and stumbled on to this site.
you pay $9 for a certified mechanic to troubleshoot your problem. you message back and forth trying different things... so far we're on step two. then, when i am satisfied... i send him (or her) the held money on my credit card. it's genius.
here is an example of the last post...
Ok, so you need to remove the coolant hose at the top of the coolant bottle (it's the small one) and hold it over the open bottle, have a friend start the car and hold the RPM at 2000 while you observe for flow out of that hose.
Also feel both of the heater core hoses near the battery (you'll need to remove the plastic trim there) and see if either one of them is hot. Are both the radiator hoses hot? Any check engine light.
Please be sure to answer all the questions I've asked as it will help me greatly in figuring out what is wrong with your car.
it's like having a real mechanic friend... ohhhh, i just felt icky. i'm paying for it.