Chrysler Repair: coolant leaks from filler bottle after engine shut off, coolant leaks, radiator cap

Question
'96 chy.t&c van leaks coolant from overflow tank when eng.is shutoff.replaced therm,both cool.fan & ac fan is wking.temp gauge shows normal when driving.????????

Answer
Hi Mike,
Could you have a leaky radiator cap? While the temp in the system will rise when you shut off the engine, it would usually not do so siginificantly enough to cause over-pressurization. So look into the seal on that radiator cap. How full is the overflow bottle when the system is cold? Note the marking on the bottle for correct level.
You may have air trapped in the system that occurred when you changed the thermostat. Drain off about a quart or so, then note that there is a threaded vent plug on the front of the block, just to the side of the thermostat housing. Remove that plug then refill the system via the radiator cap until the fluid level reaches that vant plug opening, insert the plug, then refill the rest of the radiator to the top, and then put on the cap, and finally add coolant mix to the overflow bottle to the level shown on its side.
Roland