Scotty I have a 2009 Toyota corolla le 1.8liter engine automatic 234650 miles on it. My wife usually drives it we started on a trip the temp gauge stated going up and down so i stopped and checked it nothing looked out of place. But the radiator cap was cold. hoses were hot and fans running. Took back home next morning checked it and had to add a half gallon antifreeze. I thought heater core or a leak or bad radiator cap. But heater blows hot ac works no leaks radiator hose hot only issue i see is radiator cap is cold. Fans running local shop put dye in and no leaks have been found and still holding antifreeze in radiator and overflow jug stayed at same level. Has not over heated at all even on day temp gauge went up an down from normal operating temp. Local shop says nothing wrong?? But before that day radiator cap always hot as normal. Do you have any idea what it could be?? Think it is head gasket??
Local shop put dye in and said nothing was found. Thanks again scotty.
Brian
Replace the radiator cap if it is old. You could also pressure test the cooling system, though UV dye used properly should have found any leaks. You can also get a kit for testing the head gasket, at least to the extent of checking for combustion gases in the coolant.
I appreciate it sir will start with the cap it is only like 2 to 3 years old and rubber seal looks good? Least expensive option for now. I know about 3 years ago when i flushed the system i put new rad cap new radiator and new condenser new fan assembly refilled the ac system everything been working good up until now. I appreciate all the help.
Brian