I've carefully reviewed all of FordTechMakuloco's videos as well as other videos with failing cam phasers on Ford vehicles, and in every case I could find, the sound of the bad phaser was very consistent and repetitive. The sound on my car is much more intermittent.
Tonight I went out with the mechanic's stethoscope and poked around the top of the engine with it. The knock sound is not detectable on or around any part of either valve cover. It is also not detectable along the top of the block in between the valve cover and where the aluminum intake bolts down, except for at the timing chain side of the engine in the V near the engine mount, where the sound is noticeable on both heads. It does not sound louder or quieter on either side. Checking below the engine mount and getting closer to the water pump mount location, the sound intensity increases. I can also hear the sound on the side of the rear head (firewall side) towards the bottom of that head. I also checked the front exhaust manifold where it bolts to the head and there were no irregular noises. I listened to the mounting bracket for the rear turbo and did not hear the noise which I think rules out the rear turbo. Disconnecting the power to the variable camshaft actuators made no change. I did notice that when I put my hand on the electrical connector for the front cam phaser actuator, that the there was a lot of pulsing/vibration, but the rear actuator did not have the same feeling. Also, the noise is also still there at higher RPM's, but much harder to detect as other noises tend to swamp it out.
At this point, I am leaning toward one of the following possibilities:
- Water Pump rattling and perhaps in early stages of failure
- Cam Phaser(s) or actuators
- Damage chain guides
- Damaged piston skirt on cylinder #1 or #4
Also, I remembered that for my last oil change, I used Mobil 1 Advanced Fuel Economy 0W-30 plus a quart of Mobil1 10w-30. At operating temps, this oil should not be any thinner than the OEM spec 5W-20, but perhaps the oil has something to do with it. I could easily do a quick oil change to a 10W-30 and see if it makes a difference.
I think my next step is to perform the oil change and also get under the car and make sure the noise is not louder at the oil pan or lower end of the engine.
Thoughts?