Thank you for taking the time to help.
I have read as many forums as I could find on this issue (I am sure I missed a few thousand) and now come to you for your advice.

The vehicle in question here is a 2006 F150 4X4 Lariat with the 5.4 triton engine.
Issues we are having are narrowing down the location of tapping/knocking noises.

First, on the right bank there is what appears to be valve tap that does not get better when the engine warms up. I listened closely with ¾” plastic conduit to but cannot determine if it is noisy injector or tapping valve adjuster, only that it is on the right rear or the engine around cylinders 3 and 4. But did determine it is not camshaft phaser, how can I narrow the search?

Next, there is a bottom end knock that is only there during initial start up. I have read that this is normal of the 5.4’s but find it hard to believe the owner (my neighbor) is just now noticing it. The knock is slight and other than standing next to the wheel well or laying under the truck you would almost not hear it.

Finally the one that really tosses me around is the looping tap (for lack of a better word) that seems to be coming from the front. The truck has 120,000 miles on it so I am not inclined to believe the timing chain needs to be replaced, but I do fear one of the guides may be damaged or a tensioner my not be working properly. My reason for leaning more towards the tensioner is because when I checked the oil pressure at start up, it was bouncing hard between 65psi and 75psi. At idle it drops to between 35psi and 45psi. But once the engine warms to operating temperature it bounces between 30psi and 35psi.


Is it possible that the timing chain tensioner is losing pressure allowing the chain to bounce? Would it show on the oil pressure gauge as indicated?


Thank you for your time.

 

Drain the oil and look closely for any plastic residue in the oil. If the guides are gone, there will be a lot of real fine plastic sand i8n the oil.

 

Thank you for your reply (was getting worried LOL).

The oil has always been changed on time and only MotorCraft 5w20 used. As for the oil filter it has either been a MotorCraft or a Wix filter. I took another look at the oil (placed in jug until diagnoses is over). It is clean looking to the eye but there is semi-metallic (shinny) looking sediment. It is not gritty when rubbed between my fingers. I have seen chain guides break apart and drop chunks and even the retaining bolts into the oil pan so I understand the potential problem here but I haven’t noticed anything like this.

Personally I want to pull the front off this thing and see for myself (I believe the tensioner is the most likely candidate) but my neighbor wants to know with no uncertainty.

As for the other, I have determined it is valve tap and not noisy injectors.

 

The shiny sediment is from the guide lining and metal guide wear. I agree with you that the cover needs pulled, but again, that is the owner's call. Sometimes it can be called preventative maintenance. You are saving him major costs in the future. Good luck with it.