I've encountered my first 'major' problem with the 337. I was driving
down the road the other day and my temperature warning light came on
and my temperature gauge was almost pegged. I pulled over, shut the
car off and let it sit for a few. Once the temp came down below half,
I started to drive again. Car quickly pegged out. So, I let it cool
down again. This time I turn on the AC to make sure the fans are
working, they are. OK, I drive a while and the car heats up again. So,
I continue this until I get her home.(luckily only a few miles) I do
the VAG-COM thing, no codes. I then let the car idle while watching
the temp readout on VAG-COM. Once the temps get above @ 105 C, I
decide thats enough temp for the fan to kick in.
The next day, I jumper the fan to verify that it is working. I also
put a meter on the coolant fan switch (located in lower part of
radiator). I start the car and let it get hot. No joy on the switch,
so I think "cool, and easy part to fix". Well, I start to look on the
Internet about cooling problems on VW's and in a thread somewhere
someone mentions checking upper and lower hose temps. I go check mine.
Top one HOT, bottom one, not much hotter than engine bay. OK. This
tells me that I have a flow problem (no wonder switch in radiator
never worked).
I am not losing any coolant, and there isn't any evidence that I can
see that would indicate any leaks.
Here is the deal. More than likely it is either a thermostat, or a
water pump. Without taking the right side of my engine apart, how can
I tell if my water pump is pumping? Any suggestions? I guess the
easiest thing would be for me to change the thermostat first tonight
and see if that fixes the problem, but I don't want to have to drain
the thing twice if I don't have to.
Bottom line here is Does anyone know of a procedure to see if the
water pump is flowing? Any help here would be appreciated.

(couple of hours later)

Ok, so I haven't cracked a line open yet (too late right now), and was
wondering if any of you experts out there can answer a couple of
questions. When looking at the motor (1.8t GTI), which way does the
coolant flow?  does it come out and toward the lower hose of the
radiator, then exit the top hose and go toward the engine? (Where
green temp sensor located)  If my thermostat is bad would it cause the
symptom of the top hose getting HOT and the lower hose to be at
ambient temperature?  If my water pump was bad could it cause a
similar symptom?  Just curious as I have a few hours to kill before
the parts stores open in the a.m.
  Any help would be greatly appreciated