Here is the problems we are having and this is our only vehicle so figuring out the problem is a MUST. A week ago we noticed our Temperature Gauge said the van was running hot so we got out and checked that it wasn't actually running hot at all, all fluids were full and by touching the radiator it was still very cool to the touch. Someone suggested it was possibly the thermostat so we had someone to replace the thermostat for us. Well we would drive down the road a lil bit and the guage again would start rising up saying it was running hot but to the touch it still doesn't appear to be running hot at all. Was suggested that we possibly need to replace the temp sensor, we haven't done that as of yet. We have noticed that the heat isn't heating as it should when u turn the heater on. Last night while on a drive I noticed the gauge slowing rising up getting near close to dangerous levels, we had arrived at our destination and popped the hood, it still felt as if the radiator was cool to the touch upon popping the hood noticed all the fluids had ran back into the resevior well over the max level line. We went to leave several hours later and popped the hood before leaving noticed all fluids had ran back into radiator but after driving a couple of miles back down the road the gauge began to rise again. About 15 miles down the road we heard a small knocking clicking sound and the gauge immediately went back down into the safer normal level rather than on the upper line about to be in the red and stayed there for a lil while it began to rise again after we dropped off the last child we had to take home it did this same thing again and stayed in the normal range until we got home. My husband said he could feel when it did the clicking noise on the gas pedal. Any suggestions as to what could be going on? We have checked for leaks we have found no visible leaks in radiator or waterpump area.