metallic rattle at 3000 rpm

[Robin82]

A tinny, metallic vibration/clattering sound is coming from under the car at almost exactly 3000rpm. It only appears at this point and then disappears as the revs move on.

Any ideas what this could be??

First thought was heat shielding. Seems like something is attaining resonance at 3k.

Anyone experienced this before?

 

[mr.tourette]

I had something similar recently, turned out it was the exhaust tips, adjusted the internal clip/spring mech and refitted it and fine ever since.. might be worth a look

 

[patriot66]

Hi Robin82. What model do you have ? E85 or E86 ? What year and what engine ? :?

 

[Robin82]

Hi Robin82. What model do you have ? E85 or E86 ? What year and what engine ? :?

Hi there patriot, it’s an e85 2.0i 2007 and an N46 engine I believe.

I had something similar recently, turned out it was the exhaust tips, adjusted the internal clip/spring mech and refitted it and fine ever since.. might be worth a look

Thanks, I’ll have a look. Easy to access by using a jack and stands?

 

[mr.tourette]

Hi Robin82. What model do you have ? E85 or E86 ? What year and what engine ? :?

Hi there patriot, it’s an e85 2.0i 2007 and an N46 engine I believe.

I had something similar recently, turned out it was the exhaust tips, adjusted the internal clip/spring mech and refitted it and fine ever since.. might be worth a look

Thanks, I’ll have a look. Easy to access by using a jack and stands?

Easy to access sat on the ground

 

[Jfgoldfish]

Also worth checking the rear exhaust hangers and heat shield are all intact.
The heat shield often corrodes around the fixings.

 

[Andrew Sheldon]

I have the same on my e85 2.0. It sounds like a heat shield vibrating, I did mess around/bent one near the manifold a while back. I poked and bent it around but the noise it is still there although not as loud as it was. I need to have another look to try and stop it completely but haven't got round to it yet. It makes a kind of buzzing sound is the best way to describe it. Good luck finding your problem..

 

[Robin82]

Also worth checking the rear exhaust hangers and heat shield are all intact.
The heat shield often corrodes around the fixings.

Now that you mention this corrosion around fixings, it would make sense. The sound is just like metal vibrating back and forth at a fast rate.

I have the same on my e85 2.0. It sounds like a heat shield vibrating, I did mess around/bent one near the manifold a while back. I poked and bent it around but the noise it is still there although not as loud as it was. I need to have another look to try and stop it completely but haven't got round to it yet. It makes a kind of buzzing sound is the best way to describe it. Good luck finding your problem..

I'm going to have a look this weekend weather pending. Being that I only hear it at a certain resonance, it would point towards something being loose.

 

[bg1]

I'd go for the thin metal plates behind the brakes. They create exactly that noise when on the way out. Crazy money from BMW for replacements.

 

[Robin82]

I'd go for the thin metal plates behind the brakes. They create exactly that noise when on the way out. Crazy money from BMW for replacements.

I was going to replace rear discs and brakes before xmas as they're about due. Which metal plate is this? Do you know the name of it?

 

[Zedebee]

They are just called protection plated front/rear, left/right.

Part numbers:
34116750129 and 30 (front)
34211158991 and 2 (rear)

Above for a 2.0. The fronts seem to be different across models, but the rears are the same.

 

[Benderloch]

My front brake back plates both rattled so I discovered they had both corroded around the bolt holes, so I fitted some large washers that fixed them solidly in place.
The new once’s are expensive and unless your willing to cut them you have to remove the hubs to get them in position.

 

[Robin82]

They are just called protection plated front/rear, left/right.

Part numbers:
34116750129 and 30 (front)
34211158991 and 2 (rear)

Above for a 2.0. The fronts seem to be different across models, but the rears are the same.

Thanks Zedabee

My front brake back plates both rattled so I discovered they had both corroded around the bolt holes, so I fitted some large washers that fixed them solidly in place.
The new once’s are expensive and unless your willing to cut them you have to remove the hubs to get them in position.

I'm almost certain I've got an issue with one of these plates. I can hear a slight grinding too now when the windows down. It's the rear DS wheel I think, sounds like a right ***** to fit. Hopefully i'll be able to bolt a washer - if this is the issue. Cheers

 

[bg1]

My BMW indy replaced them. Mucho cost - think they were £70 EA plus mucho labour to remove hubs and do it properly.

Then found out all we needed was washers.

 

[Robin82]

UPDATE: Turns out it was the most trivial thing in the world.
The oil sump access panel. It was virtually hanging off. Looks as though it probably came loose and then I must’ve caught it somehow as one of the corners was bent, which I’m guessing made it even worse.

It was covered in oil too, although the sump screw was tight so perhaps the o-ring needs replacing. I also had a rocker/valve cover leak, perhaps that contributed if the oil was able to make it’s way down to the sump.

Re-the brake plates - they seem ok. The discs and pads desperately need replacing though, so perhaps thats the grinding I'm hearing.

Going to replace the access panel and screw and change the oil (again). Guess it wont harm as it is a N46 engine :lol:

 

[buzyg]

Good to read you have things in hand.

 

[Jfgoldfish]

Glad you found the culprit
I wouldn't worry too much about the oily coating down there. It is worth tackling the usual suspects like valve cover gasket, vanos solenoid seals, vaccum pump seal and oil filter housing gasket; these are easy enough jobs.
You will likely find the N46 still sweats some oil! Pretty normal for these engines.