Audi Repair: A4 1.8L T over heating, radiator coolant, coolant tank

Question
No leaks in the system has a new T-stat and o-ring I had pulled the heater outlet hose to bleed system and added a tank to my pressure adaptor at the coolant tank. Fans still wont cycle with a new thermo switch and the only indication I have for over heating is the Gauge and light  that I read in the cluster. Could it be no flow at the radiator? coolant is clean, the water pump looks to be intacked when i checked cold during R&R of the t-stat. but low flow out of the heater core and a splash out from the outlet hose going to the water pump.
got me hit with a lot of money to fix need some ideas other than removing the pump to inspect and back flushing the radiator,  Head gasket?  

Answer
hi
what year is this? what splash are you talking about?
You may have low flow at the radiator ,but this is easy to check, disconnect both hoses and star putting water in upper hose (with no pressure) water has to flow easy. If water stops at upper hose -radiator is clogged.
You wrote that water pump is OK, did you try to move plastic piece thru the t-stat hole? most of them look perfect but they loose and you can spin it or feel some loose.
good luck                   pltech