Runs hot

What is your question?

When she is in drive, and pulls a hill or has been driven a while and idles she run ultra hot extremely fast. We have replaced the thermostat and have checked for any leaks. She is full of antifreeze. I would say whatever is wrong come on gradually but now I pulled one small hill and half way up she was boiling hot. It took 1and a half / 2 hours for her cool off and start again.

What makes this problem better or worse?

After driving or pulling a hill

How long has your 1999 Hyundai Elantra had this problem?

I’ve stopped driving her