I'm new to this forum but I own an 03 Grand Cherokee which I've put a couple grand into so far. Problem I'm having now is my coolant reservoir keeps filling up. I've replaced every major component relavent to the cooling system. I just put a brand new water pump on yesterday, the radiator is new as well as the thermostat. I bled the system the best I can but I'm still having coolant go into the over flow tank, but when I run the heater on full blast it slow but surely drains back into the radiator, as well, I just replaced the radiator cap today.

Any suggestions on what I'm missing?

 

It's normal for coolant to flow in and out of the overflow reservoir as the vehicle warms and cools. When the engine gets warm the reservoir fills and as the engine cools it empties back. There are usually two level marks on the reservoir to indicate proper coolant levels one is hot and the other is cold. The amount in the reservoir should be close to one of the marks depending on engine temp.

 

The coolant expands and goes into the reservoir after the cooling system reaches the set pressure of the radiator cap. Have you replaced the radiator cap? It's an often over looked part of the cooling system.

 

Ya I replaced the rad. cap today with one of those nifty motorad caps that has a pressure release valve on it. I think the problem is there is still a small amount of air that has yet to be worked out of the system, plus I need to drain the over flow tank a little bit. A little too much fluid in that.