Have to replace about a gallon of water each morning lately but there are still some days when it does not happen at allWhy does the temp gauge on Plym Voyager go up and down ? Replaced thermostat, no change?check for leaks. also maybe a head gasket is leaking.Why does the temp gauge on Plym Voyager go up and down ? Replaced thermostat, no change?It should fluctuate.. and you'd see this more on warm up. The engine is closed off from the radiator until the coolant temperature reaches temp (usually 180 degrees). Once that thermostat opens, the cooled, unheated coolant from the radiator surges in, cooling things off in a hurry... then that's where the thermostat will close again, because it is not efficient to run with a cold engine (parts wear out faster, poor gas mileage). It will cycle back and forth until the engine and the rest of the cooling system even out and where the thermostat cycles less and less (stays open more consistently). It should NOT go to the extremes... from C all the way to H, but rather stay in that normal flex area (usually marked as notches in the middle on the temp gauge) and stay there.
About the loss... Sometimes the overflow container or hose has a leak... when the radiator comes up to temp, and coolant up to pressure, the extra coolant runs to the reservoir.. but then on cool-off it sucks in air and that overflowed coolant never returns.. Is your reservoir dry?
