Hello all, I have a 98 F-150 4.2L and I have a strange problem, after driving down the highway about ten miles or so the heater stopped blowing warm air and the engine started overheating and I could hear a knocking sound in the engine compartment I got off the highway to a gas station and checked the coolant and it was empty and the oil was low, I keep regular maintenance and the truck has 96.000 miles on it I filled up the resevoir and the filled the oil and everything went back to normal. But a few days later the same thing happened, I don't see any leaks externally and I think the oil is burning due to the overheating after I get low on coolant. Does anyone have any ideas what is going on? I don't see where the coolant is leaking but it has to be going somewhere and I did smell a hint of coolant inside the vehicle so is it leaking internally or what, any help would be great. Thanks

 

You may have a minute crack in your intake manifold. I experienced something similar in an old S-10 I had. All the coolant went into the oil system. The oil became very cloudy. Get it fixed or you can ruin your engine. I hope this helps.

 

Thanks Rick's98 I'll sure check that out.

 

More than likely, you have a leaking front timing cover gasket. Coolant is getting into your crankcase. Get it checked ASAP.

 

Your lower intake gaskets have failed,most likely on cylinders #1 or #4,or both,and has caused your engine to hydro-lock.Your engine has bent a rod,thats the noise you are hearing.The 97 and some 98 4.2V6s have this problem.The only cure now is to either replace the bent rod and bearings,or replace the engine.