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Coupe/m3 Annoying Dashboard Internal Plastic Rattle/vibration Fix (Problem Actually Located In Engine Bay)

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Hi all, did a quick search to see if anyone had covered this but I didn't find anything so hopefully this helps someone as I've heard about this problem a few times.

So, my 2001 pre-facelift coupe has had an annoying plastic-on-plastic vibration/rattle that sounded like it was coming from the centre of the dash behind the middle air vents.

It resonated at about 2000rpm and was proper annoying when changing down gears or when travelling between 20-30mph as it got so loud it sometimes confused me into thinking I'd accidentally put it into first gear and my engine was straining or something.

It was reaaaally annoying, and after taking part my dashboard to no avail, I decided to root around the back of the engine to see if anything was loose, and after dismantling various parts and ages of annoying my neighbours with engine revving I found the problem.

I know a rattle can be caused by some plastic bits inside the dashboard, behind the head unit and middle air vents, but this wasn't the case with mine. And to be honest, this was easier than taking the bloody vents and what-not out.

I'm not sure what models/years are prone to this, and I'm not sure how the engine bays differ on each model/year of e46 but if you have a problem that sounds like it could be this, it takes less than an hour and doesn't really cost anything.

All you need is:

Some silicone/mastic sealant.

A torx screwdriver. (didn't check the size I used, sorry!)

Right, this is where you'll be working:


Step 1: Unclip and remove the plastic wiring loom/hose tidier so the wiring loom and hose are loose. Then, undo the three spring-loaded clip things on the cabin filter cover.


Step 2: Lift the front of the filter cover up and pull towards you to remove it (there is a lip on the back of it that slots under the rubber seal above it). At first I thought this was attached to the plastic trim under the wipers as it wasn't going anywhere, but after some "gentle" persuasion it came out.

Step 3: Remove the cabin filter itself by lifting slightly and sliding it towards you.


Step 4: Undo the four torx screws. One of mine was missing, the more I look around the car the more screws I find that are missing! Then lift out the heavy ass cabin filter housing.



Step 5: Lift off the rubber seal on top of the black plastic divider to the right of the cabin filter housing (highlighted in red on the two photos). Lift the grommets the various hoses and cables go through out of the slots so the hoses can freely move out the way when removing the next part. There are two of twisty screw clip things on the black wall located where the green arrows point that you may want to remove so you can push the plastic divider-wall thing out the way (sorry, forgot to take a picture of this bit).

You don't have to remove any of this from the car, just loosen it so it can lean out of the way to get the next part out easily.



Step 6: Undo the two torx screws and lift out the wall plate thing.


Step 7: You should now see the cavity that is under your dashboard and the back of your AC air ducts through a cut-out in the back of the engine bay. Around the edge of the cut-out is a rubber seal (as outlined in red, its a big 'U' shape, can't get a full pic of it in situ as it goes behind the engine). THIS IS THE CULPRIT. Over time the rubber perishes, stiffens and warps causing it to flap around and vibrate against the metal edge. If you tap it you can tell. If I'd have known this was causing the problem I would have bought a new seal, but it won't really make a difference.



Step 8: Pull it off, it looks like this.


Step 9: Now, get some mastic or silicone sealant and cover the rubber seal in that sh*t. Apply it all the way around the edge of the cut-out in the engine bay where the rubber seal fits aswell. Try not to get it everywhere like I did…





Step 10: Re-fit the rubber seal, ensuring the locating lugs go through the holes in the metal body and the rubber sits flush. Make sure mastic is spread along the whole rubber seal and making definite contact with the metal body. You are essentially just gluing the seal down to the car to stop it flapping around and vibrating.


Step 11: Refit the wall plate and tightly fasten the two torx screws. Apply more mastic over the top if you want, just to be sure.



Step 12: Put everything back in reverse order, ensuring everything is tightened properly.

I replaced the bolt that was missing, but only had a slot head :(



No more annoying vibrations or flappy rubber inside your engine bay! :thumbsup:

I'm glad I found what it was as it was doing my head in!

Hopefully this helps and solves someone else's annoying vibrating rattle noise. If not, it may be behind your radio head unit/middle air vents that your problem lies, so good luck! :)



Edited by alexlawley

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Hey Alex, I would like to thank you for your very clear instruction. I wish there were more people like you! I also don't understand why nobody have left a reply on your post. I hope you still read my reply because you just fixed my rattle noise. It was just this. I saw all kinds of complicated dash removal fixes but really this wasn't going to work. Your solution was the true solution mate! Would love to buy you a beer.



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Thank you for the vivid solution Alex. My E46 2002 facelift is giving me the same annoying rattling noise coming from the middle air vent when i accelerate above 1500 rpm in the 1st and 2nd gear.  I will take it to the repairs. I will give fit back when it's done.

Edited by Derick

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