When I put anti freeze in the cooling system, my car over heats. But when I put water in it doesn't. Does anyone know why?

 

that makes little sense.
can you provide more details?





.

 

I was driving on the highway when the car over heated. So I dumped the antifreeze and put water in and the car ran fine. Later on I had the system flushed and put in 50/50. When I drive locally it doesn't overheat, but as soon as I get on the highway the temperature slowly rises. So I had two additional fans installed and it seem to cool it down, but every two days I was putting in antifreeze in. So I went to the dealer to get new thermostsat. The next day I put the car on the road and every thing seemed fine until I went about 25-30 miles and the temperature started rising again and the new fans couldn't control the temperature. By the way I have a 1999 deville d'elegance.

 

water pump..... ??? how many miles? mine was changed, alone with the thermostat, all was well....... are you using dex-cool? i'll usually exchange coolant, not flush.....
rickyd

just another thought.... where is the coolant going? have you checked your oil? if your saying you have to add coolant.....?????? check this out and keep us informed. we need also a little more info, and history on car..... good luck

 

I have 156,800 miles on it. I use dexcool 50/50, but when I purchased the car last Feb. it had green antifreeze in it. Didn't notice it until I went to get oil change a week later. The antifreeze was filthy. So I don't know how long that antifezze was in there when I purchased the car. I had a bad leak in radiator, changed the radiator, hoses and thermostat. Car was running fine then gradually I was losing antifreeze, but lately I have to fill it up every other day. I just flushed and changed oil.

 

the anti freeze has to be going somewhere...... and i think i would exchange what is is there with 50/50 dex-cool and distilled water.... check your oil for signs of anti freeze..... when you start car or idle do you have white smoke out of exhaust?
rickyd

 

Have CO test for blown head gasket. Also have pressure test done for external leaks, heater pipes that run along rear head can rust through where straps hold them to engine.