overheating kia sportage/rear seal leak

[vixson]

I recently purchased a kia sportage 1999 4x4 with 78125 miles. It seems to overheat from in idle. There is some kinda of decomposing plastic in radiator and when I changed the thermostat today the sam e stuff was in thermostat with some kind of silver stuff on the housing. Stop Leak???
I flushed the radiator but nothing came out.
Can any one give me any suggestions.

[hvac1000]

Probably the silver poweder sealer. Home someone did not stick you with a blown head gasket. You might try a new thermostat and check the fan clutck. The fan clutch/fans have ben know to have a problem with cracking blades and fan clutches that do not hook up when hot.

[mgbgt1972]

Sounds like rad-stop leak, also used to hide a leaking head gasket when selling a car!

Since you replaced the thermostat and did a flush, you really can only check the fan, check the temp sensor, and do a compression test! after you have driven her take of the oil filler cap, if you sea any condensation or a white/beige slime on the inside of the cap then the chances are you are getting water in the oil, a sign of a failed head gasket! Also check the rad overflow tank after a drive, is if full of bubbles and have a odd coloured film on top?