98 Expedition ticking sound

[Fitz98]

98 Expedition 5.4 Triton 145K miles.
I have change plugs and boots, PCV Valve and PCV vacuum lines, fuel filter, air filter, transmission flush and filter change, oil and filter change (Motorcraft filter and Pennzoil 5W30 oil),cooling system flush, power steering flush, new brake lines and synthetic brake fluid flush and change, new thermostat.
I gotta say that this vehicle is running better than new now and with 145k miles, I am quite happy.
All that is left is an annoying but discrete rapid ticking noise.
It is most noticeable when cold and at startup, but it is also noticeable when I have the windows down and drive past a wall or another car beside me. Other than that, I cannot hear it when the windows are up.
Any ideas what this could be and a solution? Maybe some oil additive or something to free up rings, lifters, reconditon seals and or valves or something like that?

 

[crazyoildude]

One of my engine builders has one of those with the 5.4 v-8 with 225,000 plus miles using 5w20 oil out of the drums at the shop since he got it with 125,000 miles he changes it every 6000 miles and uses a group 7 filter made by purolator and his engine is quiet exept for the fuel injectors ticking..Before that my neighbor owned it and took it anywhere they change oil cheap!
We use conoco oil..good stuff

 

[OVERKILL]

Either it is a cracked exhaust manifold, broken manifold bolt(s), or a loose plug.

Those are what I have experienced causing ticking.

Check the passenger side manifold for signs of a crack or leakage around where it meets the head.

 

[mattd]

probably exhaust manifold leak. common. It can be a fun job if the bolts break. The rear ones tend to rot off to begin with, causing the issue you have.

 

[Trav]

Its easy enough to check the manifold,look for missing studs,usually the lower one near the rear,they rot off and cause a ticking noise.
This job can be one huge PITA!Been there and done that more times than i want to remember.

There is another possibility though,there is TSB about cat noise on these year expeditions,mine has it bad.Its not an issue other than noise,ford fix is to put a very expensive shield over it.I didn't bother as long as i know what it is i left it alone.
let the truck idle,chock the wheels,set the park brake and go under it.Listen to the cat if its ticking away or knocking then that could well be your problem if all the manifold studs are intact.
These older 2v engines are great but are known for their noises.They all tick,bang,knock,rattle and carry on especially when cold and have some miles on the clock.