i have a 96 sedan deville that i just replaced the themostat in a month ago and it ran fine. now its running hot again. what could be the problem.

 

Thats a wide open question with almost no information to go on.
The things you have checked and tested so far as well as when it gets hot and how hot it gets would also help.
The more info you can give us the better change we can help you fix it.

Also if you do a search on this site you will find many previous threads pertaining to overheating or running hot.

 

i have check fans, they are running,just today i have added more coolant and the temp held at 222. the belt on the water pump is turning, but for some reason there is alot of oil or grease on it. i hope this is enough to help get a reply. thanks

 

Do you see any white smoke/steam coming out of your exhaust or does your exhaust have "coolant" smell to it? If so, this is (and the fact that you are overheating) is a symptom of headgaskets going bad. And if this is the case, I am sorry to be the bearer of bad news.

 

grease_monkey1965