Metal scraping noise and fluid leak under car
Debris can get jammed into the bottom of a vehicle while driving, causing sudden scraping noises and unexpected fluid leaks. Not knowing what these unknown objects or leaks are makes it difficult to determine whether it is safe to drive or requires immediate attention.
What the numbers show
Counted from the threads quoted below. How we count
- People have been saying this in most months since September 2026.
- This comes up 9.2× more often in r/AskMechanics than across the site as a whole.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
Found another way around this?
Share your steps and trade-offs so fellow engineers don't have to reinvent the wheel. No account required.
- 1Testing the hardness of the object with a tissue paperDid this help you?
- 2Deep cleaning the room to check for additional piecesDid this help you?
- 3Asking online mechanics or car communities to identify unfamiliar items found near or on the vehicleDid this help you?
- 4Taking back roads home and avoiding potholesDid this help you?
- 5Inspecting the vehicle's wheel wells and suspension components yourselfDid this help you?
- 6checking if the substance feels wet or dryDid this help you?
- 7asking mechanics online for visual identificationDid this help you?
- 8Cleaning up the piles repeatedlyDid this help you?
- 9Putting out ant granule bait around the perimeterDid this help you?
- 10Using liquid home defense products based on online readingDid this help you?
- 11Asking online mechanics communities for identification helpDid this help you?
- 12Trying other subreddits like r/whatcaristhisDid this help you?
- 13Guessing whether the object came from the car or is unrelated debrisDid this help you?
- 14asking online forums to identify the substance from photosDid this help you?
In their words
Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.
“Did I just run over this and had it clunk inside my wheel well, or did something on my car break?”source ↗
“If this is from my car, is it safe to drive?”source ↗
“Does this look like jb Weld or a fluid leak and should i be concerned? It's hard to the touch. If it's jb weld, what is it protecting?”source ↗
“Hello, i was involved in a hit and run at night and it left behind some taillight parts. I need some help identifying”source ↗
“My mum pulled out from her parking space and the neighbour noticed this underneath the car. I’m guessing it’s not from the car itself as it’s thin and light, but then I’ve no idea. Does anyone know if this is a car part or something else unrelated?”source ↗
“For some time now i find those "puddle" of matter on the floor under the engine bay of my car the day after i've used it.”source ↗
“I have no idea what this could be”source ↗
“I was driving and suddenly I started hearing scraping. So I stopped and saw this thing sticking out of the bottom of my car.”source ↗
“There was also fluid leaking near the front as well. Does anyone have any idea what it is?”source ↗
“Is it common for stuff to just get jammed in the bottom of your car like that?”source ↗
“I have a 2019 Chevy Trax, found this hanging from the bottom of my car right behind the rear of my front driving well on my left side, right below the drivers door, I nudged it with my foot thinking it was a stick that got caught but I’m worried this could be a component that shouldn’t be out of place at all”source ↗
“I had this exact same looking thing, thought it was some type of mould as it was on the middle of the floor in the back garden shed. There was water around”source ↗
“Last week I noticed some sand at the corner exterior of the structure, I thought maybe it was the wind that brought some dirt around the corner and cleaned it up.”source ↗
“Today I saw another pile and started cleaning it again until it finally clicked that it isn’t the wind causing the dirt to pile up.”source ↗
“I don’t see any ants near the pile, but I am concerned it could potentially cause either structural damage (in the long term) or may cause an infestation. Can someone help me confirm if this is ant related?”source ↗