Loud rattle from rear deck

[caf2461]

Try as I might I cannot find the rattle coming from the rear deck area. The back seat is out and speaker covers. I have not removed the rear deck - have not figured out how. It is more loud when cold. It sounds like a glass tap when going over bumps. Any suggestions?

[Ross]

To remove the rear parcel shelf the seat and high stop light must come out. It then slides out after removing a few clips that will be apparent once the seat is gone.
From here I'd guess your strut mount(s) are done.

[ScottyWM]

Yup, sounds like strut mounts to me too.

[myles]

No need to remove the high stop light. It sits under the shelf trim and isn't attached to it.

[632 Regal]

Loose speaker?

[caf2461]

It is not obvious from the rear speaker or deck cover where the sound is coming from so I went ahead and ordered new Boge strut mounts. I replaced the beer can bushings weeks ago with polyurethane and they were shot. Perhaps this had contributed to showing the strut mounts were bad? Once the strut mounts come in will dig into it.

[genphreak]

Rear strut mounts are major wear items in e34. A major design flaw as they are only worth $40 each, these days BMW ensure that wear items are more expensive ;)

[caf2461]

Looks like I did not think to order bump stops. Mine are really shot. Guess dealer is the only local option?

[caf2461]

Well I replaced the rear strut tower bushings and they were fine. Replaced the bump stops they were gone. Noise still there. Had my wife drive me around with me in the back and it was so intermittant I could not find it. Found when I parked the car on an angle slope I could reproduce the noise by lifting sharply on the rear wheel well. Probed and looked and finally found the problem. In front of the strut tower there is a sandwiched panel that the back of the seat lays against. The panel is 2" in front of the strut tower top where the rear firewall attaches to the metal rear deck. There was a gap here (when the car was parked on an angle) and a spot weld that had failed. The weld would tap loudly when I moved the car up and down. I pried the two pannels slighly apart and the noise went away. Shoved two peices of wire ties in the gap as a spacer and sealed the area with clear sealant as a preventative measure. I finally can drive the car without going mad.

Characteristics:
It was louder when cold out.
It would only do it over small bumps or rough road.
I could only reproduce the noise when the chassis was twisted in the slope of my driveway - could not reproduce when level in garage.
I could not feel the noise through the strut tower only on the panel imediately in front of it.

I thought sure it was the strut tower bushings.........

[genphreak]

Awesome close-off to this problem dude, really good deduction work too. U had all us armchair mechanics foxxed!

Thanks for contributing the fix!