2004 Nissan Pathfinder with 4 wheel drive. It has the 3.5L VQ35DE engine.
This little black hose that you see coming up on the back of my engine every time I engine gets up to operating temperature bleeds out my coolant but my car is at normal operating temperature. It will continue to blow coolant out of this little valve until it gets low on coolant and then starts overheating. I have determined that is the issue because if the car is running and I keep topping it off with coolant it will never overheat but the entire time it is gently spraying out of this black hose that comes up. And it is hooked up directly to the cooling system. Like as soon as it starts to warm up and build pressure in the system it just starts peeing out the top. And it looks like there used to be some kind of hose or something like that on it. I have no idea what it is. I just bought this car 2 days ago and the first time that this happened I just assumed it was probably a thermostat because the car had sat for like 2 years. So I replaced the thermostat and then flushed out the cooling system. I tested the water pump and it works just fine. I flushed out the heater core as well. It runs and operates perfectly other than whatever this little black pipe is. It is a metal pipe with a little bit of black residue on the last inch of it almost as if it used to have a hose or some kind of cap on it. I don't recall seeing anything on it at any point in time when I was inspecting the car. It didn't overheat or anything like that the entire 2-hour drive home and after I got home it was sitting there idling for a few minutes while I recharge the AC system and in the course of doing so I noticed that it started to overheat. So I quickly shut it down and let it cool off and then started working on the cooling system. Am I missing a part to the pipe or is there some other underlying issue?