Hi Everyone, New member here. Bought a 1996 W210 E300D diesel with 181K miles. Have searched this forum and did some work. Replaced all fuel delivery clear hoses/ o-ring, cleaned intake manifold gump. Then coolant start to leak at thermostat housing. Order one with seal. Surprise is, when I opend the T-housing, I see no thermostat inside. Check with local mercedes dealer. They said some owner just wanted to by-pass it, recommend to put it in. I did. No more leak. Did several 5, 10, 25 miles test drive at around 80 degree F outside. Now the temp gauge at the board, stay around 98 degree C when no air or heat is on. When heat at HI, it drops 2 -4 degree C to 96 - 94 C. But when AC on at 66 C, temp gauge jump to 102 C. IS THIS NORMAL? If not, what could be wrong? I see no leak or stranger noise at pump, upper coolant hose hotter than lower with about same pressure when I use my finger to press it afte it 5 min of drive. Hi fan seem to squeek a bit sometime. Please chip in. thx