Thermostat (Page 1/1) Rhodesia1977 DEC 11, 10:27 AM On a cold engine, if I open up where the thermostat is on the 2.8, should I see coolant in there or should it appear dry? Which cap do I open to see if the water pump is circulating the fluid, the thermostat housing or the cap on the radiator? Thank you! Cliff Pennock DEC 11, 12:18 PM AFAIK, if you remove the thermostat cap, you should always see coolant. The thermostat cap is also the cap to remove to see if coolant is circulating.