What do scratches and marks on engine cylinder walls mean?
Visible markings or potential scoring seen on cylinder walls through a borescope often create uncertainty about whether the engine has sustained serious damage or cylinder wash from a no-start issue. This leaves owners unsure if the marks are critical or safe to leave alone, or what cleaning steps might be necessary.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
- 1Spraying brake cleaner through a straw to clean and inspect the surface better
- 2Consulting online forums or mechanics to verify if the marks are normal manufacturing artifacts.
In their words
Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.
“I got under my 2009 Honda Pilot with 200k miles and noticed there is what looks like spider cracking in the transmission case. I'm not sure what it means, or if it's a ticking time bomb?”source ↗
“Okay. Bear in mind I had not established the fact that I fear I may have fuel washed the cylinder bores because my car has had a no-start issue for months and it turns out it's a ground issue, but I was cranking the engine hoping it would fire up but spark is not present. Fuel is involved here, but I thought I might've scored the cylinder walls as a result. So, do you see anything that looks serious? What would happen if I don't clean it with brake cleaner?”source ↗