2001 F250 5.4 with 160K miles. My wife "borrowed" my truck as she drove away, I saw white smoke coming out of the tailpipe. The kind you see in cold weather. Its was 75 degree in Texas this morning, so what could that be? There is antifreeze in the reservoir and I recently changed the oil and there was no water in it.

 

Most common cause, of course, is coolant getting into the cylinder(s). Another , much less common, possibility is a fuel injector sticking open. If you don't know how to test for those problems, you should get someone who does to look at it. Too complex to try to diagnose without someone actually looking at and doing test on the vehicle.

 

I would not worry about the white smoke if the truck was just started and drove off when you noticed it. If it has white smoke when she arrives back and the engine and exhaust system is at temperature, then check for coolant leaks into the combustion chambers.

white smoke - water
blue smoke - oil
black smoke - fuel

 

was it white smoke or steam you saw. if you short trip the truck alot they muffler will fill with water. then steam out when you drive it on freeway or after exhaust is hot. if you do not notice a drop in coolant or coolant in oil i would just keep a mental note of it and not freak out much

 

Thanks. It did burn off after few minutes. I guess I will keep my eye on it for now. I don't drive the truck a lot, maybe one time a week. That may cause the water to build up for sitting too much. I did not think of that.

 

When the truck cools, it is common for a little water to condense and settle in the exhaust system, especially in humid climates.

As long as the "white smoke" isn't real heavy and goes away after a few minutes of driving, it's normal.