So this one is weird. I originally diagnosed as chain tensioner bleedoff, but now I don't know. It has Motocraft 5w20 and motocraft filter FL820S(i think is the #). I let it sit all night, 8-10 hours, start it up in the morning, sounds beautiful. No noises. Drive to work (fully warmed when I arrive), let sit 4 hours, go to lunch, and when I start it there is a light rattle from the valvetrain it appears, for 1-2 seconds at startup and then all is normal.

Temperatures in Maine are ranging low 20s overnight, 20-30 during day, today was somewhat warmer, 35-40 or so. I didn't pay attention when I went to lunch if it did it, but I got back to work around 1230 and when I left at 1600, it had sat the entire time and had the light rattle.

Its currently under warranty for another month and 1500 miles or so, and I want to be sure it isn't something serious before it runs out so I can get it addressed now. The general consensus is these motors are somewhat noisy at startup and its entirely normal. Engine sounds great, runs great, no CEL, has plenty of power and last mileage check yielded 18 on the highway, so all looks and appears to be in order. Just trying to determine if my noise is normal.

I had a theory that the oil was still somewhat warm and the phasers were just adjusting from the "off" position but I'm not so sure. 4 hours of sitting seems to me like it'd be long enough for the oil to cool down to the point where the phasers are in the "non-operational" condition until the oil warms up.

Appreciate any help in advance.

 

My truck does the exact same thing every now and then. I have not been able to predict when it will happen. Some mornings it starts smooth as ever. And some mornings it rattle for about a second and is smooth again. I have had my truck looked at by 2 different dealers and a personal mechanic and I have been told it is totally normal and these phasers are just noisy. Never had a code pop up or anything. I have been led to believe that it's just the phasers adjusting back to where they need to be. Hope it helps. If you hear differently id like to know because I have also read that dealers say it's normal until it's out of warranty so they don't have to pay for bad phasers or solenoids.