I have a 96 nissan sentra it has 101,380 miles and I notice the other day that the car is using the resever of the radiator is very low I had the radiator check no leaks where found. I fill it to max and in a couple of hours the same thing happens there is no antifreeze puddle underneath the car. Someone told me it could be the heater core, but they also told me that when it's that the passenger side floor would be wet full of water well mine is dry. I also notice yesterday that the heater was throwing out warm heat, not hot last night I fill the reserve again and this morning was still full I went out to drive the car for a while checked it and the reserve is still full I turn the heater this morning and it's heating very hot now, I don't know what is happening if there is a mechanic out there that can help please answer my thread.

Thank You

 

Im not 100% positive, but there may have been a leak in the system that pluged itself up. Remember not all mechanics will find things like that. So it may have leaked somewhere and some rust may have filled the hole and stoped the leak and when you filled the resevoir twice it replenished the system. It could be something else like the engine got way to hot and it evaporated but I really dont think that way it.

 

what was the water/coolant mixer like? my 1989 Nissan hardbody use to do the same thing till i did a flush and fill and then it stopped then i found out the guy sold it to me with only water in the radiator