2015 XLT 4x4 with 3.5 Ecoboost with 3700 miles. I have what I can best describe as a clunk that can be felt in the brake pedal and seems to be coming from the drivers side front wheel area the first time the truck reaches 24mph after being in park. It only happens the first time you reach that speed after being in park and can be replicated over and over again by just putting it in park and then driving again. Has anyone else experienced this or have some thoughts on what it might be? I have a few of the other issues I see discussed on this site and when I make a service appointment I want to be able to provide them as much info as possible. Thanks

 

I had been lurking the forums for a long time waiting to see if anyone else was having this issue- I felt like I had to register when I saw your thread.

I too have a 2015 XLT 4x4 3.5 Eco. I'm at about 5,000 miles but it's been doing it (or I have noticed it) since at least the second week that I owned it.

I had this checked out along with some driveline lash/clunking when accelerating after coming to a rolling stop. The service advisor told me that he had had a few others complain about the driveline lash but had not had anything in for the 25 mph clunk. After dropping my truck off for the day for diagnosis, he came back with TSB # 44996:

44996: 2013-2015 F150, Expedition, Navigator, and Transit - 3.5L GTDI popping sound on cold startup

Some 2013-2015 F150, Expedition, Navitator, and Transit vehicles equipped with a 3.5L GTDI engine may exhibit a popping sound on cold startup that can be isolated to the Charge Air Cooler (CAC) system or air intake area. The Powertrain Control Module (PCM) will open the turbocharger bypass valve during cold engine start-up. After about 30 seconds, the valve closes, which may result in a popping sound. This noise is considered normal operation and no repairs should be attempted to resolve this condition.
Effective Date: 19-March-2015

I really don't think this is the issue as searching around the internet it seems like this is fairly common and the guys that have this happen have it happen at idle and definitely not at a specific MPH like us.

There was also this thread a while back and all of these guys definitely do not have the 3.5 Eco:

https://www.f150forum.com/f118/clunk...l-well-314235/


If you get yours checked out, let me know what your dealer says.. doesn't seem like this is very common so it may be difficult to get it acknowledged and fixed.

Edited to add: Mine only does it the first time you hit 25 MPH after starting, not each time you hit 25 after being in park like yours. Strange..

 

I have the exact same issue on mine. The issue only occurs the very first time I reach 25mph after start up.

I was thinking the sound was the power running boards locking (safety feature) but based on what y'all have shared that doesn't seem to be the case.

 

Definitely not power running boards in my case as my XLT just has the fixed tube-style boards.

LedZep, what engine do you have? 4x4 or 4x2?

I originally thought it had something to do with the 4x4 system as the sound seems to come from the driver side wheel well, but for me the noise happens with 4x4 engaged as well which would seem to rule that out. Now thinking maybe it has to do with the ABS system since OP can feel the clunk in the brake pedal..

 

Mine is a 3.5Eco 4x4 with 3.55 gears. The sound I hear the clunk noise from is the same as yours. It sounds like it's just behind the wheel well on the drivers side.

I'll check tomorrow if I can feel the clunk in the pedals. So far, I've only heard the sound.

 

I have a 2015 XLT 4x4 with the 5.0... Have not run into the 25 MPH clunk you mentioned - but have experienced the clunk/lash that moford21 mentioned in regards to a rolling stop. I also have noticed this if you're coasting on the highway, then get back on it. Haven't taken to a dealer yet.. It's 2 weeks old w/ 1,200 miles.

 

I have the same issue. It only happens once after sitting. I figure a trip to the dealer will result in a "can't duplicate issue" response. I have an XLT 4X4 3.5 EB.

 

Have you guys that mentioned it only happens once tried to drive for a while and then put it in park and then drive again to see if it happens a second time? I have a few stoplights on the way home and if I put it in park at the stoplight and then put it back in drive and take off I can replicate the sound when it gets to 24mph. As was mentioned it does it in 2wd or 4wd, so I am inclined to think it is not hub related, so maybe something to do with the ABS.

 

It's 4th gear. Does it when it's cold, but never when warmed up. I think there's a TSB for it.

EDIT: TSB 15-0142 https://www.f150forum.com/attachment...sb-15-0142.pdf

It says 5-4 downshift, but I have also experienced it going 3-4.

 

Definitely not the hard 4-5 downshift. I have that as well and this clunk doesn't appear to be coming from the transmission at all.