Hey guys. I've been hearing this noise from my E90 M3 and I thought I'd post about it on here to try and get some opinions on it.
I've had this car for roughly 6 months. The car spent most of its life out here in the mid-west, started out in Indiana and is now with me in Champaign/Chicago, Illinois. I left the car in December for three weeks and came back to a semi-rough startup, but nothing too bad. I drive the car with immaculate care. I don't drive it rough often, but when I do it is 5-10 mins after everything is warm.
Starting early February, I started hearing this weird clashing/knocking noise from the lower part of the engine bay. I could only hear it when I put my head down near the left side of the engine bay, and it sent me on a frantic research. I watched too many videos on the rod bearing noise and I deduced that the noise wasn't the infamous rod bearing knock. To be completely safe, I took an oil sample from my oil change and sent it to Blackstone. I stopped driving the car for a few weeks until I got the report back and the report stated that my car didn't have rod bearing issues. My mechanic friend, however, was certain when we were doing the oil change that I was definitely spinning bearings.
I can't seem to find out what this sound is. It has become louder and louder as the time has passed. The noise also started coming out of the front passenger side wheel well as well. It has become so loud now that you could easily hear this sound if you're standing on the passenger side of the car. I think it could be an exhaust leak somewhere, but I can't be sure. I've kept looking for people with the same issue, but I haven't found anything so far. I'm currently busy with work, so I'll try my best to post a video of this later on in the day.
Symptoms:
-The noise is always heard every time I start the car at idle (Cold).
-The noise leaves when the cold start ends and the RPM slightly lifts up at the end.
-The noise can be heard when the car is less than 2000 RPM and warm, I've heard the noise with the windows down when creeping through a parking garage or through tight spacing with walls.
Please let me know what you think this is, a video will come tonight. I've attached the Blackstone below.
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