Hello, H-T!

I'll keep this short.

B16A stock + S4C trans. Powered by a B16B EK9 Type-R ECU. (Wrong ECU, I know.)

I just noticed this noise from the motor and havent been able to run any tests yet.
It sounds like a very low pitch thumping. Not quite like a knock.
It was over-revved 2 times on accident but it was very brief.

- Never been low on oil.
- Never been overheated.

Any idea of what it could be?

 

Pretty sure you just answered your own question. Most likely spun a bearing.

 

That easily, eh?

Thing is, I've heard many knocking motors and this sounds a bit different. I'll report back on findings eventually tho

 

It’ll sound different real soon lol

 

If this is what happened, do you think new bearings and possibly a rod will fix it here? Or am I looking at crank reconditioning?

 

An update: it ended up being a loose spark plug on #2. It had unthreaded and backed itself out. Rethreading it back to normal fixed everything. The sound was just compression escaping.