Greetings... I have a 1997 Ford Ranger XLT that's been sitting for somewhere around 4 years. I'm looking to get it running again and when I went to check the coolant it appears to have solidified. Poking at it with a rod it has approximately 0 give to it. I can't find almost anything about this on the web.. Is there any sort of chemical solution that can break it down? I know how to do a regular coolant flush but that requires well.. regular coolant. Tomorrow I'm planning on taking out the hose connecting the reservoir to the radiator to see if perhaps in isn't solid all the way through and is somewhere I can clear it out. Also what could've caused this? Is there an air leak of some sort or is it just because it's been sitting for so long? Even when it was run previously I don't believe it was maintained well. EDIT: Someone from another source said that they believe this is could be a result of orange and green coolants being mixed.