I really don't see how it can be driveline with the transmission in park. I watched some of the videos.

 

Exactly what I've been telling Ford, but they say its normal. The clunk can happen in Neutral as well. They say its the clutchpacks.

 

I am in a 2019 because my 2018 drank coolant and no one could figure out why, not because of a noise that happens occasionally upon startup that also happens in every other 2017-2019 F150.

 

yep, thankfully Ford didnt say it was normal or a "characteristic".

 

That's not driveline lash indeed, but rather, parking pawl mechanism lash (that's why the truck can move a little in P when brake is released. It needs it). But ALL drivelines have to have lash too; period. All gears need a little lash to prevent premature wear, and when you add all of them up, it amounts to a few degrees of rotation of the driveshaft. You can easily check it by putting the tranny in N (do it on a flat surface), with parking brake on (for safety), then get under the truck and try to turn the driveshaft with your hands both ways; you'd see it rotates slightly to one side. That's your lash. Why most cars don't make a sound at start-up? Because their drivelines have isolators (motorcycles have 'cush drives'). But apparently, Ford wanted to save a few pennies and didn't put any on our trucks, so when the lash is not taken out (happens randomly), that's the noise you can hear at start-up. It's similar to what you hear when engaging 1st on most motorcycles; the 'bang' is when the rotating tranny (due to oil viscosity applying slight torque thru the wet clutch plates) suddenly stops. It can sound bad, but it's not detrimental at all if not abnormally loud (due to excessive tolerances, or something else). It's just one of the many unrefined characteristics of our trucks. Not worth even thinking about it, unless abnormally loud. Otherwise, you could get the entire drivetrain replaced, and you'd hear the same darn thing, so why bother? Just saying .

 

Simple. Because the weight of the truck might NOT be resting on the driveline (stressed) while in P, but on its parking pawl instead . ALL drivelines need lash to operate properly, and it's a fact. And yes, if Ford wasn't a cheapskate, you wouldn't hear anything, but they are. So you have to live with this, and many other 'idiosyncrasies' of our trucks. I went in with low expectations because I did my research, so even though some of these stupid little things can be a bit disappointing, it's not worth getting worked up about it, especially since there's no solution. Again, even if you get the entire driveline replaced, it'd do exactly the same. And the reason is when the driveline is not 'stressed', meaning the truck moved a little in the opposite direction of engine rotation, the clunk happens. So the way to eliminate the problem is to first find out when it clunks, which can be tried this way: Roll the truck forward a little (if backed up), and with the brakes still on, apply the parking brake, so truck doesn't move. If it clunks, then try the opposite (reverse it then apply parking brake), to confirm it doesn't clunk. Once you know which way it doesn't clunk, you could avoid the clunk easily, and without having to use the parking brake if not needed. Hope this helps.

 

My 2015 2.7 never clunked on start up, my 2018 2.7 does, but not every time I start it. This is regardless if parked in the garage or driveway.

 

Mine never does it when the truck is cold, only after I've been driving and turn it off and then turn it back on again.

2019 f150 3.5

 

Same on my 2017

 

Mine too but the truth is I might hear it once in months doesn't do it very often!!