I think yours is the same as mine, pipe going into the top then 2 or 3 coming out of the bottom? I replaced mine because it was stuck open and the new one did the trick. Then I spotted a few drips underneath. Looked like it was from the seam on the t/stat but was actually the radiator leaking at the top corner (passenger) around the plastic. Get it upto temp and have a look. Also check the bleed pipe from the rad to expansion tank isn't blocked.
mike