This is one issue I really don't care about. Literally every single newer f150 does this. Every one. Well, I've driven seven different 2018s and 2019s for extended periods, and they all do it. SO..yeah I'd say they pretty much all do. Is what it is.

 

Mine started doing this...during or shortly after towing only tho.
On warm start ups

 

I've been dealing with this same issue since i bought my truck in March. 2019 XLT 3.5 4x4 screw with 4k miles now. Dealer told me the same line about normal operating characteristics of the 10R80 transmission. I had been driving a 2wd loaner truck 2019 XLT 2.7 while the dealer had my truck. The 2wd truck never once made the clunk. Has anyone looked into this possibly being a transfer case issue? Maybe the computer is sending a quick signal to the t case then nulling it out causing the shaft to quickly rotate. I complained to Ford and requested a buyback which was denied since i didn't meet Texas lemon law requirements. I was able to get an 8 year 150k mile premium care warranty provided by Ford so i can have some peace of mind when this thing ultimately fails. I hope they figure this out.

 

I've driven 8 different 2018-2019 F150's...all for over a week...all 4WD. Both 3.5s and 5.0s. They all did it.

 

What are we really talking about failing here?

Worst case scenario I see is it causes slight wear on the u-joints. No more than engaging drive, but it's like a double engagement each start...maybe?

 

is the common link here 10sp and 4x4? Do any of the 2wd models do this clunk too?

It must not be all of them - but clearly there's a large number. are mustangs and expeditions doing this too?

 

Common link is the 10R80 trans, but not the number of drive wheels. Same thing happens on my 2018 XLT 2WD on occasional warm starts.

 

According to 5-Star Tuning, the clunk is just way the transmission is designed and programmed. It goes into lockup mode in 2nd gear, so all the other gears make a clunk sound when shifting. They do have a tune for the transmission to change it's shift patterns and when it goes into lockup.

 

My 2019 F150 5.0/10spd 4x4 makes the same exact noise. I was curious what this was, almost sounds a bit like a cough through an old carb on start. I can see where the torque converter would transmit power through the transmission on start up if it was in a gear, but in park? It sounds like it's applying a gear momentarily as the line pressure comes up during cranking. I'd love to know the technical reason for that. At least to put my mind at ease that the trans won't fail and move under it's own power in park some years down the road.

 

Maybe that is the transmission doing a self test when you crank the engine? The 10 speed does have an electric oil pump that keeps fluid flowing in the transmission during times the engine shuts off in auto stop mode.