tdconner
New Member
1998 Ford Expedition 5.4 Triton V8 161k. If I ADD coolant to the fill line truck starts overheating and I loose heat AND the temp gauge in truck goes down. For real, engine temp goes up to about 230F (using OBD II reader), I loose heat in the truck, but then the temp gauge in the truck goes down almost to cold. If I open pressure tank cap during all this to relieve pressure and let some coolant out to BELOW the fill line, temp sits back at 199F, temp gauge in truck goes back to normal half or little below, and heat comes back HOT. I'm totally stumped. Already replaced thermostat with a new 190.
