Jimm 5/4/2013If the cooling system has a brown / tan looking color to the coolant - this is not a good sign. This condition usually indicates the transmission fluid or engine oil has mixed with the coolant. If the transmission fluid is mixing - this would indicate a leaking radiator cooling tank.
if the engine oil is mixing - this would indicate a faulty cylinder head gasket or leaking / ruptured cylinder head seal.
Have this test performed as a first step (once you have checked the engine oil and transmission fluid condition / appearance) - an engine cylinder compression test (both dry and wet readings).