i need help, again!

my coolant level light came on and usually that means my reservoir is low. while i am under the hood to add water to my reservoir, i decide to check out all my other fluids too. took my radiator cap off and the radiator was full of water, but it looks like it has rust in it and when i ran my finger inside to get a better feel for what it may be, there was little bit of build up and it wiped off black. have no idea what this may be or if that is normal. can someone help?

what year is your vehicle? I think you should put antifreeze not water in, your engine, and radiator will buildup that kind of crap if you use water, just like when you will boil water in a kettle, it will buildup stone. If i was you i would flush the entire cooling system just to be sure.

its a 94, thanks

coolant level light works off the fill tank. if radiator was full and tank was empty then level is just low. not to worry about leaks, just keep an eye on it to make sure. a little dark build up over time is normal. if it's dark gray and kind of sparkly then could be some sort of stop leak. From what you wrote it sounds pretty normal though. Purple haze is right about using coolant instead of water. If water looked really dirty i'd do the flush!