My f150 2004 5.4engine has a knocking noise for about 4 months.

Oh yea, lifters can be replaced , best if you replace cam an lifters together ! Loud knocking is not usually associated with lifters , they usually make a ticking noise ! Knocking noise is most usually in the bottom of the motor , main or rod bearings . most of the time rod bearings !

have the oil pressure checked cold and hot and at idle and 2000 rpm`s. it could also be a lifter noise. can`t tell unless actually hearing the noise.

If it is a clear metal tap,not a knock and usually is a little worse when first starting the engine and there is no miss to the engine..it most likely is a sticking or dirty hydraulic lifter..you can ask your local auto supply for a good oil additive that helps clean dirty lifters. Also after using that product for a while I suggest an oil change maybe a little lighter oil and include another additive treatment along with the oil change...this should clean and free them up..good luck..

The 3.4L engine has special pistons that are designed to expand as the engine heats up. When the engine is cold, the pistons make a knocking sound that resembles lifter noise or piston slap. As long as the noise goes away after the engine warms up, don't sweat it; this is normal.

It does sound like a valve lifter problem to me also. It should be covered under warranty. It's a mechanical failure of a component of the drivetrain. Ask them to show you the specific exclusion if they say it's not a warranty problem.Powertrain warranty is 60 months/60,000 miles ( which ever comes first).

lifters tick and noise is upper end of engine if lifters are making noise could be from a bad valve,bad lifter ,push rod ,oil pressure,rocker arm - need to take do compression test find out if valve problem and which cylinder is problem also take off valve cover and check for proper oiling of valve head and look to see if and are damaged or loose-------a knocking sound usually comes from lower end of engine,rod knock etc.and thats usually rebuild of engine

check oil level .was correct oil put in engine

noise is caused by lack of oil to lifters, or worn timeing chain. if noise is from lifters it should go away wit proper oil level, if still there needs timeing chain.

Sounds like a lifter noise. worn lifters can't keep oil in them anymore so over night the oil leaks out. when you start the vehicle, you will hear a ticking noise or knocking noise till the lifters fill with oil again. only remedy is to replace the lifters.
you could try an additive but it's temporary.