i need help on my engine n52b30 have coolant lose.No leaks no smoke in exhaust and on expansion tank no oil combinating with water but about 1000km i have message low water and water pipes are hard like concrete.Buble test on head is ok no one bubles.it doesn't matter is full throtle or on idling pipes are too hard radiator is hot vent is on.Heating is ok no overheating only coolant losing any ideas?
I have oil consumption about 1L to 1000-1500km Oil consumption is relatively ok but coolant i have not ideas.
many thanks

 

It could be steaming out somewhere. Check thoroughly under the coolant tank, around the temperature sensor, the hose on top of the radiator and inspect the tank cap. If all else fails, use leak dye.

 

Check for any signs of coolant leaking into the engine cylinders, such as white smoke from the exhaust or a sweet smell in the exhaust fumes. Even if the bubbling test on the head is fine, there may still be an internal leak that is causing the coolant loss.