Lately I've been noticing an excess of smoke coming from the tail pipes of my exhaust. It's like when you start your car on a cold morning but does it constantly. It does slow down just a bit after about 10 miles of driving. The oil is changed every 3,000 miles. It does burn one quart in between changes which I understand is normal. The oil looks good, it looks like oil should. I have however noticed a drop in my coolant. I loose about an inch of water every month and a half from the overflow tank. My thinking, is that a gasket on the intake manifold has gone bad allowing coolant into the exhaust system, thus causing smoke. I have noticed NO loss in power and everything else seems to be in good working order. Truck is a 2002 f150 with the 5.4 triton. 139,000 miles. Thanks

 

An inch in the tank is also an inch in the radiator. Probably 1/2 gal or so.
Any sign of stumble or misfire on cold start that would signify leak into intake runners or cyl heads?

 

Do a block test. Here's one example: http://blockchek.com/instructions.htm

 

Not at all! Runs very well from startup. And I'll check out a block tester soon!

 

Thats good
Id check mode 06 for misfires that havent tripped code.
Then look for high fuel trim on a bank, coolant in exhaust will fool the computer into thinking its lean

Also check csrefully for external leaks, especially in heat soak when coolant pressure is highest, and water pump while running.