I hit a big pothole with the right front corner of the car a few weeks ago, and ever since I've had a mysterious clunking noise.

It sounds like hitting the car with a hard rubber mallet. Not quite a metal-on-metal sound, but close. It makes the noise on broken pavement (especially low speed) and any sharp bump. There's no noise from lower frequency suspension movement (going around corners, over gentler humps, etc). On a sharp, hard impact like a pothole, the noise is a loud BANG. I can't replicate the sound by rocking the car or dropping it hard-ish from the jack.

I've checked everything for play and found nothing obviously wrong. Ball joints seem fine. Suspension bushings seem fine. Sway bar end links don't have play. Brakes are not rattling (doesn't sound like that anyway). Motor/trans mounts are fine. Exhaust is solid. I removed the right front strut assembly and replaced the strut mount with a new one and that didn't help anything. No obvious damage to the strut tower sheet metal, etc.

The car drives totally fine with no vibration or misalignment.

The car has Bilstein PSS coilovers. I lubricated the spring/perches in case it was binding somehow, but that didn't help. The strut appears to be in good shape, but I'm wondering if it could have some sort of internal damage caused by the impact.

Anyone had this issue, either with these coilovers or more generally?

I'm pretty experienced as a DIYer, but I'm at a loss on this. It's the ONLY thing wrong with the car and I'm getting ready to sell it, so I'd like to solve it ASAP.

 

Might need to remove the strut and check it for damage. Once it's apart it might be more apparent. Do you have the stock ones you can put on to see if the issue goes away?

 

Nope.

I've had the strut assembly apart once already to install a new strut top/bushing/bearing. Had it up again today to try a new sway bar end link and that didn't help either. Nothing was obviously wrong, but the clunk continues to get worse. Maybe at some point it will actually break and let me know what's wrong...