Frustrating interior rattle - Please help me find it!

[Mallone]

As part of lockdown I've been sorting a bunch of interior niggles out as my OCD can't live with a car that has a load of random interior vibrations and rattles.

Ever since I bought the car, and especially since fitting the firmer engine mounts, I've had a really, really, REALLY, annoying interior rattle from the rear of the car that I can't seem to find and it's making me tear my hair out trying to find it.

Opening up to the forum to see if anyone has any smart ideas! I know trim noises have a bad habit of sounding like they are coming from somewhere they are not, so hoping someone might have had to solve a similar problem before.

The noise only shows up with the engine under load. Flares up when pulling away and will rattle/buzz constantly at around 2800-3000 rpm. Sounds like a relatively loud high pitched buzz and initially I thought it was only coming from the rear passenger seatbelt/C pillar area.

Finally got round to pulling out all of the interior trim to try and get to the bottom of things. The good news? I'm £9 up from change found in the seats and down the back of the carpets. Result. The bad news? I cannot find this rattle at all.

I'd initially thought that the noise was coming from the trim itself, and once I'd pulled it off I replaced a bunch of trim clips and applied felt tape everywhere I thought it might need it, but that didn't make a difference to the rattle and driving around without ANY trim in the car will still result in the same noise.

Without trim in the car and on the move it sounds like the noise is coming from the quarter glass on both sides, and with the rear 'door cards' and c pillar covers removed on both sides the only way I can recreate the noise is by giving the metal body a thump below the quarter glass windows. However, both windows seem secure on their mounting bolts and tapping on the glass, or applying pressure to the glass while giving the metalwork a thump to recreate the noise, won't change anything. Not sure if that removes them from the equation? Is there more adjustment here to try and firm them up? It sounds like maybe the noise might be coming from deeper in the rear wings but not sure if that's my mind playing tricks on me.

Otherwise I've checked every random nut/bolt in the rear of the car to see if anything is loose and can't find anything. I've removed the third brake light and applied tape/foam to make sure that wasn't rattling about in it's housing. I've applied foam and felt tape to any/all mountings that I thought might be vibrating. Could the rear seat belt mechanism's make this noise? The wiper mechanism? Feels solid to me.

I'm running out of options, but logical next step is to start removing the headliner to see if anything is buzzing around and the sound is travelling.Starting to clutch at straws. Anyone else got any bright ideas?!

 

[Paynewright]

I know your pain - I'm chasing a dashboard rattle and have removed the glove box, double din and all the middle dash - drive around the block and its still there!! It sounds like a washer rattling on a loose bolt.

Have you lifted the carpet parcel shelf and checked all the relays? I had one vibrate out!

Also have you taken a passenger out with you to prod, poke and push things to see what makes it stop? On mine if you push hard between the radio and passenger air bag it stops - the latter is coming out next!!

 

[MisterCorn]

I would definitely check the headlining rods, they can come out and rattle. With the trim off they are very easy to get at to check.

MC

 

[nickyg63]

:yeah:

I have rattle where the headlining meets the rear window. I will check that out when i can.

Thanks

 

[Phil 997]

I had the same , it drove me mad and as you I stripped out most of the interior inc the Bose amps , seat belt retainers etc etc, I was confident the rattle was internal , I put a bore camera down the rear arch between the inner and outer skin as I know these cars get rivet heads break off during the build process and they jam in the rear arch sometimes rattling sometimes causing the little outie nipples we see on the bodywork around the rear arches. anyway there were three of these rivets in the gap so we removed them using a Flexi screwdriver with blue tac stuck on the end lol . but annoyingly the rattle was still there , we removed the high-level brake light panel and found some loose wiring loom that rattled when we touched it so we secured that. rattle still there :dont know: finally we walked around the outside of the car on touching the rear bumper where it connects to the rear arch the rattle stopped , it turned out to be a loose screw that fastened the corner of the rear bumper to the rear arch . job done :thumb: until the next one . I also had a rattle on my 997.1 that turned out to be a loose spring on the Tiptronic lever ,that also took an age to find :grin: :grin: good luck and hope some of those suggestions turn out to be your rattle. :thumb: :thumb:

 

[EGTE]

Something I learned from Renaults back in the day: blobs of Blu-Tak are fantastic at damping out rattles.

Work them into suspected cracks and crevices until they disappear.
:thumb:

 

[Paynewright]

Phil,

I think you need to set up a 'rattle cancellation' consultancy - all work on an hourly rate!!

Ian

 

[Phil 997]

Phil,

I think you need to set up a 'rattle cancellation' consultancy - all work on an hourly rate!!

Ian

:floor: :floor: payment in bacon butties :grin: :grin:

 

[Mallone]

Just to update - think I've finally sorted it. This has taken months!

After my post this morning I went out to the car and decided I wouldn't leave until I'd found it. Felt like I spent most of the day crawling around in the back of the 996. Not fun!

In the end, after much, much, much banging and tapping and shaking and my neighbours definitely thinking I'm going crazy, I narrowed it down to.....the mechanism/lever for the fold down rear seats :roll:

Bit of sticky foam to take up the slack, new trim clips for the rest of the car and, at least for my first test drive this afternoon, complete silence. I can't tell you how happy this made me! Fingers crossed it sticks and I've got the right rattle.

It's obviously highlighted some other annoying noises - a knocking from the passenger door that will need looking at - but that's car karma and completely expected.

Project cars are never really finished/fixed, right?!

 

[Marky911]

Well done on finding the main one. As you've found though another one will come along and take its place.

I may be remembering them with Rose tinters but the aircooled cars were generally better in the interior department. I did have the odd rattle in my 964s but not as many as 996s.
Mind you the trade off was the diagonal seating position and air-con that never works (even when technically it is working). :grin:

 

[skinny_monkey]

Well done, I'm at the adding foam stage behind the trims. I hate rattles. Found that on my centre console the handbrake panel wa quite a loose fit which caused a very annoying rattle at idle.
Where do you find trim clips by the way, im guessing i have to go to OPC when they're open again.

 

[Paynewright]

I'm proud and slightly jealous !!

 

[Phil 997]

Excellent its sorted and yes its expected that there will be another rattle that was being masked by the first one. also great we can add rear sear folding mechanism to the list of possible causes :thumb: :thumb: :thumb:

 

[Mallone]

Well done, I'm at the adding foam stage behind the trims. I hate rattles. Found that on my centre console the handbrake panel wa quite a loose fit which caused a very annoying rattle at idle.
Where do you find trim clips by the way, im guessing i have to go to OPC when they're open again.

I ended up getting everything from Teile.com

Prices are cheaper per part than D911, but postage is a bit painful. They were the only guys with stock at the minute so I was a bit stuck. I think OPC's will probably be open in a couple of weeks though.

Shout if you need a hand. I've accidentally developed an encyclopaedic knowledge of 996 trim clip types and locations, as well as how best to damp any rattles they might make.....:grin:

 

[MisterCorn]

Trim clips are one of the mysteries of the Porsche catalogue. Really not very well documented. Best part of lockdown easing for me will be OPC reopening. My parts list is growing.

MC