Subtle clunk noise when flooring it or slamming on the brakes - any ideas?

[markinsf]

Hi All,

Late 2018 MX here. For at least a year now I occasionally hear a clunk noise when I mash the accelerator pedal. Likewise, the same noise if I slam on the brakes.

Took the car to the service center and I couldn't reproduce the problem. Seems to happen more going up a hill or if I mash it at about 20mph (when the acceleration is most forcible).

After driving around for 15 minutes with a service guy in the passenger seat and beating the crap out of my car, I could not reproduce the noise.

I've thoroughly searched the interior of the car to ensure it's nothing rolling around. And, from the slightly muffled sound, it seems as if it is coming from underneath the car.

Any ideas? Or do I just have to wait until it gets more noticeable/problematic before the service center will do anything...

Thanks.

 

[john pane]

Passenger seatbelt.

 

[StanMI]

Something loose in the glove box between front seats ?? I had a container of hand sanitizer wipes in ours. It would roll sometimes and it sounded like something under the hood was banging around. Took me a long time to figure it out.

 

[chukiechz]

Front tow hook sliding in frunk maybe?

 

[aesculus]

Any chance you hear a clunk going over speed bumps or rougher roads at <20 mph? Front air struts can cause this. More prevalent it seems in MS (or they are more picky). I am on my third set.

I also had a bad sway bar link bushing that caused a clunk.

 

[StanMI]

Front tow hook sliding in frunk maybe?

That what I thought mine was, it was not.

 

[markinsf]

Hi All! Thanks for your replies. But it is definitely not something moving around in the interior, in the frunk (the tow hook is stuffed under the carpet), or in the rear storage area.

The clunk slightly reverberates throughout the car (I can even feel it in my seat and the gas pedal) which makes me think that it is a drive train problem.

Not sure about other services centers but mine seems to do as little as they can. I have this problem and the problem of my auto-open driver's door not fully opening from the front and they can't/won't fix either problem.

 

[fr100]

Does it sound like this?

 

[markinsf]

Does it sound like this?

Thanks for the video. It was interesting to watch this. But, what I'm experiencing is more like a muffled thunk and I really have to mash the gas pedal or slam on the brakes to hear it.

 

[shamaryounge]

Thanks for the video. It was interesting to watch this. But, what I'm experiencing is more like a muffled thunk and I really have to mash the gas pedal or slam on the brakes to hear it.

I have the same issue, it's a super loud thunk, I've only heard it twice, both times it was when I had to slam on the brakes. First time I heard it, I was driving and didn't realize my turn was coming, so I checked my mirror real quick to make sure no one was behind me and hit the brake, I didn't push it to the floor, but I pressed it firmly and as the car jerked to stop, I heard the loudest "clunk"come from the rear and I felt it reverberate throughout the car. I thought I hit something on the road and broke a part but I checked the car, no damage, and I checked the road, there was nothing. Second time I heard it, I was accelerating quickly, someone decided to pull out in front of me so I had to let off and hit the brakes, that was when I heard it again. It sounds like a motor or a drivetrain issue, you know the small clunk sound when the car turns on and the high voltage contacts engage, it sounds like that but ten times worse.