* Oil cooler line leak: The oil cooler lines run between the engine and the radiator, and if they develop a leak, engine oil can mix with the radiator fluid, turning it black.
* Head gasket leak: A head gasket leak can allow engine coolant to mix with engine oil, which can also turn the radiator fluid black.
* Blown head gasket: A blown head gasket can cause significant engine damage and will likely result in black radiator fluid.
* Transmission line leak: If the transmission lines develop a leak, transmission fluid can mix with the radiator fluid, turning it black.
It is important to have your Cherokee checked by a qualified mechanic as soon as possible if you notice black radiator fluid, as it can indicate a serious engine problem.
