Weird vibe/fluttering noise in dash???

[motuman]

Here's a stumper for the group. I've owned three e34's and this is the first one that's had this problem.

I have a 95 540/6 and when I hit 60 mph or above on the highway I am getting a weird noise from inside the dash. It is kind of a buzzing/fluttering sound and it's pretty loud. (ie. almost loud enough to disrupt conversation in the car). The sound is intermittent and it can last from a few sconds to a minute or more. Sounds like it's coming form the center/driver's side of the dash.

It sounds like air is passing over one of the mode doors in the HVAC system and causing it to flutter at a high rate of vibration. The problem with that theory is that adjusting the heater/ac controls has no effect on the noise. I can turn on/off the outside air or recirc., turn on/off the a/c, turn the fan to high low or off and none of those things affect the noise. The old "hit it with a hammer" test doesn't work either. The only thing that will make it go away (othet than just waiting for it to stop on it's own) is slowing down the car.

I desperate for a solution that doesn't invlove pulling the dash (which I'd like to avoid at all costs), but I'm not too optimistic.

Any ideas out there?

Thanks to all!

[Russell]

check archives. there should be a bit on the plastic panels at the base of the windshield. They can be loose and make a lot of noise.

[motuman]

Thanks for the tip Russell. This noise is definitely inside the dash and is a fairly high frequency vibration, not a rattle.



check archives. there should be a bit on the plastic panels at the base of the windshield. They can be loose and make a lot of noise.

[Ross]

Isn't there a vaccuum hose to the back of the cluster??
Try a bigger hammer!

[BillionPa]

i have a blower fan doing that, i hit the air speed to full for a second and it goes away

[genphreak]

You're all wrong.

It's the Pressure Adjusting Device (under the drivers windscreen wiper). At this age they are all suffering dry lubricant. Everyone that has a 535/530/540 with the (ie special 'bahn speed wipers) need to pull the PAD out (you need a T20/25 Torx head and a 5mm Allen key, plus spanners and sockets to get it out (on a US car they can be accessed from inside the firewall openings just behind the fuse box. You have to remove it carefully not to lose the ball and socket and adjuster pin. Look it up on the online ETK first. I have posted about them in the past. There is a good write up on Sean and Johan's e32 pages.

If you don't fix it the nylon cogs inside will crack/wear from the strain you cna hear them going through. It might bend your wiper arm too as it can get out of synch and pressure it too much. Watch for signs of that (ie where the arm may be hitting the bonnet) its easy to bend back, but like many things on these cars takes a special knack.

New PADs can be bought form BMW too. Bloody excellent little device, it delivers a perfect wipe at 240kmh you know.... :) Nick

[motuman]

That's one I never heard before!

So this device could make noise (or flutter) even when the wipers are not in use? If so, I guess the wind force on the static wiper arm is providing the input energy?

Thanks for the suggestion!




You're all wrong.

It's the Pressure Adjusting Device (under the drivers windscreen wiper). At this age they are all suffering dry lubricant. Everyone that has a 535/530/540 with the (ie special 'bahn speed wipers) need to pull the PAD out (you need a T20/25 Torx head and a 5mm Allen key, plus spanners and sockets to get it out (on a US car they can be accessed from inside the firewall openings just behind the fuse box. You have to remove it carefully not to lose the ball and socket and adjuster pin. Look it up on the online ETK first. I have posted about them in the past. There is a good write up on Sean and Johan's e32 pages.

If you don't fix it the nylon cogs inside will crack/wear from the strain you cna hear them going through. It might bend your wiper arm too as it can get out of synch and pressure it too much. Watch for signs of that (ie where the arm may be hitting the bonnet) its easy to bend back, but like many things on these cars takes a special knack.

New PADs can be bought form BMW too. Bloody excellent little device, it delivers a perfect wipe at 240kmh you know.... :) Nick

[bigtallsam]

that was an interesting suggestion indeed

i think it's probably the plastic panels - scuttle panels?

my 5 was missing some of the clips that hold them down when i got her and had the same noise i think although mine only seemed to to it on the motorway - try tapping the panels round the wiper area with ur finger, if their loose thats probably it - i could have sworn it was coming from inside the car but turned out it was those panels, i've been wrong before though :)

s

[Russell]

still think it is the panels

[Anthony (M5 in Calgary)]

still think it is the panels

Yup - been there, done that.

Get some black RTV and lay a thin bead where the plastic cowl covers meet the glass at the base of the windscreen. Let it dry and you're golden.

[genphreak]

That's one I never heard before!

So this device could make noise (or flutter) even when the wipers are not in use? If so, I guess the wind force on the static wiper arm is providing the input energy?

Thanks for the suggestion!Look up your wipers on the online ETK to see it. It is a motor inside an allumium casing (gearbox) that drives (via a large nylon cog) a nylon spindle in an out- putting pressure on the wiper arm through a pin in the pivot (ie the arm shaft) itself. No the wipers do not need to be on, it will move around according to the speed of the car, which is why you don't hear it until you first drive hit say 30mph.

Its an inexact science though, the operation of the PAD is (AFAIK) relatively undocumented except for here (http://bmwe32.masscom.net/dutch740/wipertensioner.htm)... :) nick