I had the 300 out today for the first time in about a month. When I got home and parked it, I noticed a very small wet spot on the concrete under the overflow tube. The upper hose had pressure so the cap is doing it's job. This was the first time I ran the car in hot weather (95* here today) this year. Anyway, I got my IR thermometer out and the thermostat housing was 212* but the temp sending unit only measured 187*. Why the drastic change with them being so close together? Is my thermostat going?
