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Knocking sound under car


Icebird
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Hi, recently, when I drive over road bumps, sometimes I hear a knocking / metal creaking sound from underneath the car. Sound seems to be coming somewhere behind the driver seat. It does not happen every time I go over bump and more in cases when I go a bit faster over bigger bumps. Any idea what could be the problem? My car is about 6 year old BMW.

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Nobody will have an idea unless the car is being lifted and the rear wheels removed so that the mechanic can have a closer look.

This forum is not tech support. Your car is not a pc or a laptop.

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I also have this knocking sound behind the drivers seat

when I go really fast over humps.

The faster I go the louder the sound.

Then I realised it was my MIL sitting behind me

hitting her head on the roof.

:D

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4 minutes ago, Jamesc said:

I also have this knocking sound behind the drivers seat

when I go really fast over humps.

The faster I go the louder the sound.

Then I realised it was my MIL sitting behind me

hitting her head on the roof.

:D

I understand the situation but fail to see the issue. 😁

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Maybe loose exhaust pipes, if not suspension components worn (which would be further back). 

Or James secretly strapped his MIL under the car.

 

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Internal Moderator
13 minutes ago, Watwheels said:

Nobody will have an idea unless the car is being lifted and the rear wheels removed so that the mechanic can have a closer look.

This forum is not tech support. Your car is not a pc or a laptop.

I agree. But there's nothing wrong with asking for advice la. If not what is a forum or social media for, especially a CAR forum? It's ok to ask for advice to know roughly what you're getting into but please go to a car workshop to diagnose and get it fixed. You can seek advice, talk about life, rant, start a discussion on matters that affects you till you can't sleep, or just GWGB haha. 

If we still want MCF around ten years later, then I believe we can be a lot more receptive. [flowerface]

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1 hour ago, Icebird said:

Hi, recently, when I drive over road bumps, sometimes I hear a knocking / metal creaking sound from underneath the car. Sound seems to be coming somewhere behind the driver seat. It does not happen every time I go over bump and more in cases when I go a bit faster over bigger bumps. Any idea what could be the problem? My car is about 6 year old BMW.

Did you ask "who's there?"

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1 hour ago, Icebird said:

Hi, recently, when I drive over road bumps, sometimes I hear a knocking / metal creaking sound from underneath the car. Sound seems to be coming somewhere behind the driver seat. It does not happen every time I go over bump and more in cases when I go a bit faster over bigger bumps. Any idea what could be the problem? My car is about 6 year old BMW.

While perception has it that the sound might be coming from behind your seat, the sound could likely be from the shocks, get a mechanic to jack up the car should be able to narrow down the cause.  

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Hypersonic

just need to reply who's there and let the car finish the joke

then the issue would be resolved

🤣

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Mine also have. Initially, it was creaking sounds, especially during hot weather. Now, it's some clanking/knocking sounds when going over rough surfaces.

I am prepared to leave it until the shocks are screwed. After all, aeroplanes also emit a lot of sounds during take-off/landing....LOL

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The undercarriage of our cars is all link together. 

If the sound is on off and very min. Its extremely hard to pin point the exact fault.

No mech can tell u 100% change what parts confirm can fix.

Absorber link  to absorber mount to the bearing to the linkages to link bushing to lower arm to ball joint and the whole system link to the cross member to the steering rack ,tie rod rack end.

Etc etc.

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2 hours ago, Jamesc said:

I also have this knocking sound behind the drivers seat

when I go really fast over humps.

The faster I go the louder the sound.

Then I realised it was my MIL sitting behind me

hitting her head on the roof.

:D

I'm more surprised she doesn't give you a whack on your head..😁

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3 hours ago, Icebird said:

Hi, recently, when I drive over road bumps, sometimes I hear a knocking / metal creaking sound from underneath the car. Sound seems to be coming somewhere behind the driver seat. It does not happen every time I go over bump and more in cases when I go a bit faster over bigger bumps. Any idea what could be the problem? My car is about 6 year old BMW.

Maybe is bushing, maybe is something loose. Need to jack up and have a proper check.

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Yes best to jack it up 

and have his bush checked

by a professional.

:grin:

32 minutes ago, kobayashiGT said:

Maybe is bushing, maybe is something loose. Need to jack up and have a proper check.

 

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Supercharged

I'm hypochondriac

but for cars

I'll check the simple and stupid things first

i.e. toys stuck under the seat (if you ferry young kids)

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11 minutes ago, Phang said:

I'm hypochondriac

but for cars

I'll check the simple and stupid things first

i.e. toys stuck under the seat (if you ferry young kids)

Not to mention spare tyre loose😅

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1 hour ago, Beanoyip said:

I'm more surprised she doesn't give you a whack on your head..😁

She did but I always wear protection.

:grin:

image.png.3970535553be42248406be9248f32138.png

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