I have a 1986 2wd pickup and when i pulled into the yard Thursday and shut it off i heard a gurgling from under the hood. Checked it out and found a brownish gray sludge ozzing out of the overflow. I checked the oil and the level was down but there wasn't any signs of coolant in the crankcase. I bought this truck several months ago and hadn't had any problems with it until now. I drained the radiator and flushed it out and this was when i found that either there isn't a thermostat or it is stuck open because when i put the water hose to the upper hose it kept circulating through the system. After refilling radiator I cranked it back up and noticed that there wasn't any flow at all and the water started getting hot immediately. I am taking this to be that the water pump is shot, most likely the blades are corroded off. Could this lead to the oil getting into my coolant or could it be timing cover problems or even just the head gasket? I am looking for a direction to head before tearing it apart.

 

You probably blew the headgasket on the exhaust side. When this happens, exhaust fumes are forced in the cooling system and out the overflow tank. It has happened to a few members here before.

 

Could be that the PO blew a head gasket took the thermosat out and stop leaked it leading to the color of the coolant.. I have seen this several times before..I will NOT buy a truck if the coolant is dark colored and no thermostat.. dead give away