my millenia is overheating no leaks what could be the problem it drives well for about an hour

Could be a faulty thermostat, an internal head gasket leak, low coolant level, or a coolant temperature sensor acting up. Need more information to solve this one. Have a mechanic pressure-test the cooling system to see if it holds pressure. I have seen overheating from a problem as simple as old anti-freeze or a radiator cap that no longer holds pressure.

I have a 1998 Mazda Millenia too. Its overheating and we cant figure out why. Trying to find info on thermostat location / replacement seems next to impossible online - any suggestions? There is def coolant - it heats up and spews it out, so we keep having to replace it. I had my coolant flushed about a month ago - they didnt report any leaks. any help would be most appreciated.

I have a 97 Mazda millenia. It overheated on me on the way to work and cut out on me. I made it to work a little late after I let it cool for a little while. I noticed that the nipple on the reservoir was busted and leaked all the coolant out. So I replaced the reservoir and noticed that the nipple on the radiator was also busted. So I replaced the radiator and added more coolant. It ran fine for a day and I noticed that my car was starting to get hot again and it started smoking again and it started to smell bad. Does anyone know what the problem could be? I'm kinda limited on cash so anything cheap that will solve the problem would be greatly appreciated.

check your cooling fan relay switch... under the hood, near the fuze box... there are 2 there... 1 is engine... 1 is cooling fan... I had the same problem and replaced half the cooling system before i checked the electrical side.

What does it mean when your 1998 Mazda milenia is overheating with a leak?

I have a 2002 Mazda millenia 2.5l i would like to know why it overheats without even driving it for half an hour. what could I do?

I just had a similar issue with my 2002 Millenia S. I replaced the rear bank spark plugs and a couple days later for the very first time it started overheating. After hours upon hours of trying to diagnose the issue and thinking it was a faulty water pump, thermostat and even head gasket, later it had dawned on me that I forgot to bleed the coolant lines. When I reconnected the radiator hoses I had trapped air inside the lines and it caused the car to overheat. All I had to do was remove the radiator cap and squeeze the large coolant hose below the reservoir repeatedly until air bubbles stopped rising from the fluid and make sure the fluid was at the proper level. Now the car is running flawlessly. It is an easy thing to let slip your mind, but always make sure your lines are bled entirely before jumping to a larger conclusion. It could be something as simple as this and save you tons of money.