I installed this Motorad 180 T-Stat a couple/few years ago, long before any bad mouthing of this part had started. All has been well with temps staying between 194-198. When ambient temps reached 110* in the summer, I would occasionally see heat soak of 208* (after hot start ups). I've been noticing small temp spikes lately just running around town in cool weather, so I finally ordered the grey Genuine LR 180 T-Stat, installed it yesterday. As you can see in the pic (kinda), the black rubber seal inside the Motorad t-stat was coming apart!! That black rubber gasket is supposed to be seated down inside the t-stat. This is looking down inside the "pump" port of the t-stat. My new t-stat is running about 8-10* cooler already. Awesomeness. Thought I would share this...

 

Search the forums you'll come across horror stories - Motorads are garbage. I experienced the same symptoms as you with dislodged rubber seal. Genuine 180 is the way to go if you intend to maintain the factory designed cooling system.