Acceleration clunk when letting off the gas… anyone else dealt with this? 2015 3.5 NA with 236k miles

If I push the gas hard after a stop and then let off completely after a bit, I hear this strange clunk from the front end. I got under the car (fit without lifting it) to check things out. The bushings seem fine, calipers are tight, the lower control arms (LCAs) are newer with no rust (I’m in the rust belt), and the bolts all look tight. Sway bar links are okay too. The only thing that seems off is the struts—they’re pretty crusty and look old.

It feels like maybe a failing U-joint causing play in the drivetrain, but this is a front-biased AWD, and I didn’t notice any U-joints. Anyone experienced this or have ideas?

I’m not a mechanic, but have you checked the engine mounts? I had a clunk on my 2016 2.3 when letting off the gas, and it turned out to be the mounts.

Case said:
I’m not a mechanic, but have you checked the engine mounts? I had a clunk on my 2016 2.3 when letting off the gas, and it turned out to be the mounts.

Update: Found out the front left strut is completely shot. Replacing it soon.

Case said:
I’m not a mechanic, but have you checked the engine mounts? I had a clunk on my 2016 2.3 when letting off the gas, and it turned out to be the mounts.

Update: Replaced the struts, but the clunk is still there. I also checked the engine mounts, and they were worn, so I replaced those too, but no luck. Both LCAs are in good shape as well.

@Brenner
Did you replace all three mounts? I think one of them is technically a transmission mount or something. I had to do all three on mine.

Case said:
@Brenner
Did you replace all three mounts? I think one of them is technically a transmission mount or something. I had to do all three on mine.

Yeah, I replaced all three. Turns out the problem wasn’t the mounts—it was the driver-side CV axle. It was bad.

@Brenner
Glad you finally figured it out!

Case said:
I’m not a mechanic, but have you checked the engine mounts? I had a clunk on my 2016 2.3 when letting off the gas, and it turned out to be the mounts.

I agree with checking the mounts. Anytime I’ve had a lift and clunk issue, it’s been a mount or bushing.

I’ve got a 2017 3.5 NA 2WD with 98k miles. We had motor mounts and CV axles replaced under warranty a while ago. Every now and then, there’s still a weird clunk, but it’s been driving fine, so I haven’t worried about it.

@Rin
Update: Looks like my front left strut is done for. Hoping this solves the issue.

I get something similar on my 2013 with 150k miles. I figured it’s just something odd between the transmission and the PTU when there’s no gas input, but RPMs are up.

Not much help, but I hope you get it fixed!

@Corey
Update: Front left strut was the first issue I found, but it wasn’t the fix. Ended up being a bad driver-side CV axle.

@Corey
Thanks anyway! This just started after a 4-hour trip with some aggressive driving, so I’m hoping it’s something small.