Loud squealing air bag or something ? When I start my car

Ever since I got it the air bag or something in the back has been squealing its not a problem with driving but I wanna replace what I have to and I need help and finding out what it is and how much it will cost me
It's a 1995 740il

hi, and welcome to BimmerFest!

To be honest, I've never heard of an airbag that squeals.

We need you to give us a bit more info.
Does it only squeal at start up?
Does is still squeal at a warm or hot start up?
Can you pinpoint more closely where in the back the squeal is coming from?
Are you sure it's not coming from the engine bay?

Well it's I'm positive that the noise is coming from the back and it's always making that noise the only time it doesn't make that squealing is when we hit a bumb or go into a dip in the road

Sorry I forgot to say hello

I just came outside and took a video of it but I can only mail it to you or text you the video

Originally Posted by sealbeach740

hi, and welcome to BimmerFest!

To be honest, I've never heard of an airbag that squeals.

We need you to give us a bit more info.
Does it only squeal at start up?
Does is still squeal at a warm or hot start up?
Can you pinpoint more closely where in the back the squeal is coming from?
Are you sure it's not coming from the engine bay?

...

Let's try to narrow it down a bit then.
Next time you're driving, and you're hearing the squealling noise (if it's safe) put your 7 in neutral & coast & see if still hear the squealling.
That was we can maybe eliminate the driveshaft & rear end.
Also, while your coasting in neutral, rev the engine a bit & see if the sound of the squealling changes.

Does the sound change if you're turning left or right?
If you put the brakes on, does the sound change?

I'm just trying to get a little closer to what's causing the noise.

Originally Posted by sealbeach740

Let's try to narrow it down a bit then.
Next time you're driving, and you're hearing the squealling noise (if it's safe) put your 7 in neutral & coast & see if still hear the squealling.
That was we can maybe eliminate the driveshaft & rear end.
Also, while your coasting in neutral, rev the engine a bit & see if the sound of the squealling changes.

Does the sound change if you're turning left or right?
If you put the brakes on, does the sound change?

I'm just trying to get a little closer to what's causing the noise.

The sound changes like when you go over a bump or a dip and if your at a certain pitch meaning not level it will stop

Well, I don't think I'll be able to help you much.
If you can't hear the squealling when you're driving downhill or uphill, but only going on level ground, I don't have a clue what it could be.

One idea though........the rear exhaust mount has been known to cause squeaks. If it were my car, I'd get under the car & spray the mount with some WD40 (or anything similar), just to temporarily see if the squeak stops.

Other than that.........

Okay ill be sure to try that
Thanks for the help tho

Park brake cables rubbing on something? Check all rotating parts for clean areas where rubbing is occuring. Oh and +1 on exhaust mounts.

Hi there,

I had a similar issue with a squealing noise in my 2001 740i. The symptoms that I was seeing were as follows:

- Squealing noise from right rear of the car
- Noise persisted whether the car was moving or stopped
- Noise disappeared almost completely after filling up the gas tank
- Noise reappeared when gas tank got below about 1/2 full

I eventually came across this post on another forum, which references BMW service bulletin B 16 02 98: http://www.bimmerboard.com/forums/posts/110831 Basically, this service bulletin identifies an issue where a fuel tank check valve can create a squealing noise under certain conditions, and identifies a replacement part for the check valve. In my case, I had a local independent replace the check valve and the fuel pump at the same time, and this seems to have corrected the issue. So if you find that the noise is less noticeable with a full tank, you might be seeing the same issue. Best of luck with troubleshooting!

I don't think it's the gas tank because even if I fill it up which is rare for me now it still makes that noise