Hey guys,
Unfortunately my 2008 E90 M3 started knocking yesterday, just 3 days after I bought it. I also own an E93 Competition M3 (rod bearing done 2kmiles ago), so I’m familiar with these cars, but this one caught me by surprise. The previous owner told me the rod bearings were done about 40k miles ago.
Here’s exactly what happened:
1. Low-oil warning
While driving, the iDrive warned that the engine needed 1 quart of oil. I found it odd, but the engine sounded normal. I added the quart and let the car sit for ~2 hours while I used my other car.
2. First signs of knock
Later that same day, I drove the M3 for about 10 minutes and started hearing a faint/light knock. My immediate thought was rod knock.
3. Stopped driving and inspected
I drove it very gently for another ~7 minutes to limp it home, then stopped completely. I had the car towed the rest of the way.
Engine idles perfectly
No misfires
Knock becomes more noticeable around 2k RPM
Pulled the oil filter and found metallic flakes (“glitter”) - attached pictures.
4. Main question — is the engine salvageable?
Has anyone had success saving an S65 with a polish and new bearings once knock starts, or is this usually a crank replacement situation? I’ve heard a few stories about polishing working, but I’m not sure how realistic that is. Also is there any correlatio to the loudness of the knock and the damage in place.
Any insight or similar experiences would be greatly appreciated.
Unfortunately my 2008 E90 M3 started knocking yesterday, just 3 days after I bought it. I also own an E93 Competition M3 (rod bearing done 2kmiles ago), so I’m familiar with these cars, but this one caught me by surprise. The previous owner told me the rod bearings were done about 40k miles ago.
Here’s exactly what happened:
1. Low-oil warning
While driving, the iDrive warned that the engine needed 1 quart of oil. I found it odd, but the engine sounded normal. I added the quart and let the car sit for ~2 hours while I used my other car.
2. First signs of knock
Later that same day, I drove the M3 for about 10 minutes and started hearing a faint/light knock. My immediate thought was rod knock.
3. Stopped driving and inspected
I drove it very gently for another ~7 minutes to limp it home, then stopped completely. I had the car towed the rest of the way.
Engine idles perfectly
No misfires
Knock becomes more noticeable around 2k RPM
Pulled the oil filter and found metallic flakes (“glitter”) - attached pictures.
4. Main question — is the engine salvageable?
Has anyone had success saving an S65 with a polish and new bearings once knock starts, or is this usually a crank replacement situation? I’ve heard a few stories about polishing working, but I’m not sure how realistic that is. Also is there any correlatio to the loudness of the knock and the damage in place.
Any insight or similar experiences would be greatly appreciated.
