Metallic tapping 3k-4.5k under load

[Helmsman]

Originally Posted by PorkchopExpress

Hi Guys,

I searched the forums and found a few threads alluding to this behavior, but none of the threads had a definitive cause of this behavior.

Car-
2009 BMW M3 w/DCT, 45,000 miles with a good bill of health

Essentially, I hear a metallic tapping coming from the engine compartment when the motor is under load between 3,000 to roughly 4,500 RPM (left rear). I've thrown a rod in a motorcycle, and this sound is very similar. That being said, I only hear it at that specific RPM range. I've driven some built LS cars that have a noisy top end, and I am pretty sure this isn't a noisy valvetrain.

The sound is louder if more load is placed on the car (such as going up a hill in 3rd-4th at those RPM ranges).

There is no loss of power (that isn't in my head ) and no codes are being thrown. Idle is smooth, and there's no stumbling in power delivery.

Is this a known harmonics issue that other people have noted, or do I need to go get my car checked?

TIA

A video would help but metallic "flapper" type noise under load at that RPM range as mentioned may be induction noise. I have it between 3300-3800 isch (from when I bought the car at 11k miles) wich initially had me worried. Did some research and decided it was fine. Also changed filter, cleaned up the filter area and tighten the cover which toned down the noise a bit and made me certain.
You could obviously have a totally different type noise, again hard to tell.

Good luck!

[PorkchopExpress]

Thanks to all for responding. I had someone take a look at it today so I didn't need to drop it for a day and pick up a loaner.

Good thing too...

Originally Posted by thekurgan

There is a natural resonance around that rpm, but mostly heard through induction. This makes the foam filters sound much better whereas in many engines, they don't make much sound, just more dirt

Originally Posted by Helmsman

A video would help but metallic "flapper" type noise under load at that RPM range as mentioned may be induction noise. I have it between 3300-3800 isch (from when I bought the car at 11k miles) wich initially had me worried. Did some research and decided it was fine. Also changed filter, cleaned up the filter area and tighten the cover which toned down the noise a bit and made me certain.
You could obviously have a totally different type noise, again hard to tell.

Good luck!

You guys are right on the money. Ended up driving around listening with the tech and he said it's harmonics and nothing to be worried about. I was told that if the sound I heard were actually mechanical, it would be deeper sounding.

I can upload a vid of the sound if anyone is interested.

Otherwise, I will continue to driver her like I stole her.

[Azurite M5]

Are you sure it's not pinging from a bad batch of fuel.

[8600RPM]

Hysteria at its best. Rod bearing hysteria has gotten ridiculous

[///M Power-Belgium]

Originally Posted by 8600RPM

Hysteria at its best. Rod bearing hysteria has gotten ridiculous

What ?.... Hysteria ?
Don't think so... If you only would know what is happened Worldwide in only 3 months !
EDIT => Just saw this and it's only bearing hysteria #130 http://www.m3post.com/forums/showthr...1069180&page=6

[PorkchopExpress]

Originally Posted by 8600RPM

Hysteria at its best. Rod bearing hysteria has gotten ridiculous

It's better than worrying about getting ebola.

[Helmsman]

Originally Posted by PorkchopExpress

Thanks to all for responding. I had someone take a look at it today so I didn't need to drop it for a day and pick up a loaner.

Good thing too...





You guys are right on the money. Ended up driving around listening with the tech and he said it's harmonics and nothing to be worried about. I was told that if the sound I heard were actually mechanical, it would be deeper sounding.

I can upload a vid of the sound if anyone is interested.

Otherwise, I will continue to driver her like I stole her.

Would still be interesting to hear if you can load up a video mate.

[Killerfish2012]

Originally Posted by 8600RPM

Hysteria at its best. Rod bearing hysteria has gotten ridiculous

+1! right up there with I see dead people.

[Killerfish2012]

Originally Posted by ///M Power-Belgium

What ?.... Hysteria ?
Don't think so... If you only would know what is happened Worldwide in only 3 months !
EDIT => Just saw this and it's only bearing hysteria #130 http://www.m3post.com/forums/showthr...1069180&page=6

130 internet rod bearing failures out of how many thousand M3's produced. Yep, the failure rate is still at 1% or less.

[MFL]

Solution: Eisenmann Race Exhaust
"What noise?!! I only hear this sick ass exhaust!"

[PorkchopExpress]

I think you guys are having hysteria about hysteria.

Seriously, you're on a car forum where people get together to share thoughts and ideas. I'd have written this post regardless of the current "Rod Bearing" situation. Why? Because I have noise that i don't understand coming from my expensive car, and would like to better understand what it is and the root cause.

Now there's an actual case of harmonics that's verified that other people can find in their search results. Yay! Too bad they'll also have to filter through all of the replies from you enlightened souls quick to throw out the word "hysteria". sheesh