Prestone makes a good radiator flushing kit that should do the job on that mud-like crud you described. Such crud develops from not properly changing the coolant at the recommended intervals. Make sure if you don't buy premixed coolant to fill the radiator with once you have flushed it, that you only mix distilled water in with the fresh coolant. Zerex G-05 is a good choice of coolant that is available in both pre-mixed and concentrated (unmixed) versions.
Thanks for the quick response. I've had this problem before about 4 yrs ago and the mechanic then suggested I flush my engine and that jeeps had a tendency to do that. Everytime i bring it to get serviced i always ask does it need a flush and they say no. Anyway i did buy some prestone flush and I'll get the coolant you prefer. Thanks again for your advice!
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