i drive a 91 civic dx with the 4spd. so i was on the freeway and my temperature needle went up to almost all the way. i was about 4 minuttes from home so i just went home. i looked at the overflow tank and it has black crud in it. it almost looks like little black pellets. also there is an area of some black sludge. could this be oil or something from the radiator? help please. thanks

 

Sounds like your water pump crapped out. The impellers may have eroded down and broke apart making debris which wears down the impellers even more. Pull it off and check it out. Might as well replace that thing, flush out the system, and hope you didn't damage anything else from the overheating. Be sure to use Honda's coolant which is already pre-mixed. Oil would look like oil, or chocolatey depending on what's happened. Check and replace the thermostat as well, could have gotten stuff clogged up in it.

Janos

 

could have had a leak in the past and someone put radiator stop leak in it. ive done it before and it just made things worse.