Happy to announce that the rattle-maker was located and disarmed ... this is one of those things "you wouldn't believe me if I told you" ... I went to a mechanic friend who has a garage and a professional hydraulic car lift ... we prepared ourselves to tackle the central propshaft removal (which is not that easy on the 3.6 ... a lot of dismantling required on the dual exhaust, need to remove the engine bottom metal lid ... etc ... and, by sheer luck, we've identified the issue much sooner than anticipated ... I've tried to rattle the propshaft to identify where exactly the noise was coming from (thinking it was the central propshaft bearing), and my friend was watching the location in question ...

 

What followed was a "blimey" moment, because it turned out to be that the central propshaft bearing bridge (see first photo, marked red - not my propshaft, an example found online) was freely moving around ... it is usually held in place with 4 bolts (2 on each side) ... Guess what? Only one was in place (loose), the three of them were missing their heads! What happened at some point in time (and prior to me obtaining the car last September), whoever was driving the car hit something (maybe even a high kerb), which knocked off (actually, cut off) 3 out of 4 bolts' heads ... the remaining bolt, even though it was probably factory tightened, went loose over time and extra load, that's why I've felt the rattling more often and more distinct as time passed ... now it seems funny, but I've been several times under the car (several other mechanics as well), and no one noticed this to be an issue ...

 

The bolt heads were removed/cut off with such precision, you wouldn't know they're missing (the situation almost looked like a factory job, like it is supposes to be looking that way) ... of course, the protective long plastic covers (which I removed some time ago - see my other topic) had some damage marks on them, but nothing apart from that, that would point out that whatever was hit actually made impact on a critical fastening component of the propshaft (since there was no damage to any part of the exhaust or anything else on the bottom of the car) ... anyways, after straightening the bolts, they were unfastened and removed, we replaced them with 4 other bolts. Went out for a test drive and, voila ... no rattling anymore ... hard to find the words to explain the feeling now ... great that it was solved, but feeling stupid for not noticing something so simple and obvious ...

 

 

 

 

 

I am amazed it took you this long to find this rattle. All of those parts replaced for no reason and the expense and nobody could find something obvious like that.

 

 Is Stevie Wonder your mechanic? 

Like I've said, now it seems funny ... but, at least I have new silent blocks (suspension elements) on the front and rear suspension ... new rear shocks ... some other suspension elements also new ... almost a new or refurbished central propshaft ... ... I don't think of it as much of an expense, the car being 10 years old now and most of those would have to be replaced some time soon ... the friend was joking and said: "You know, if we hadn't noticed the movement of the propshaft bridge, we'd figure out where it was loose when we would have to unfasten those 4 bolts ... ", which, thinking logically, probably wouldn't occur before full removal of the exhaust ... what I am now well aware is that the Superb, especially the 3.6 4x4 DSG, is a highly complex piece of machinery, and logic doesn't always apply to it and you're forced to think outside of the box and expect the unexpected to be the root cause of an issue ...

Edited 30 May, 20188 yr by vborovic

At least you have got to the bottom of the problem and can enjoy your car, we all know how annoying it is to have a rattle bothering you.

 

Also good that you came and updated this thread, which people on forums never seem to do unless they are regular users. 

I tend to think of my cars as DIY projects, and if I can help other people (seeing as I'm investing a lot of time, energy and money in that anyways), why not invest a few more minutes to help ... it is easy to adapt to the silence, or, lack-of-thumping-over-potholes ... but now some other noises for which the Superb is famous are more apparent ... squeaking, creaking and a whole bunch of other animals ... ... again, over bumps or similar physical disturbances to the wheels while driving ... now the next thing on my to-do list is the Haldex filter & oil, better safe than sorry ... since i now know the propshaft is in good condition /at least for the time being), I can proceed with that regular maintenance task without worries

Edited 30 May, 20188 yr by vborovic

Our was a loose rear disc shield/guard. It sounds like the exhaust is going to fall off or is dragging along the ground.

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Edited 9 January, 20197 yr by FlyingSpanner

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Edited 9 January, 20197 yr by FlyingSpanner

One more source of rattling located (depending on the state of the air guides - outlined in red) ... even if they're new, they rattle around the surrounding plastic, figured this out by unintentionally, while doing some other work and removing the front bumper completely ... if one of the three plastic hooks is broken (which holds them in place) the rattling is that much more pronounced ... they're a long single-piece plastic that goes from to to bottom behind the bumper central horizontal beam, as seen on the photo below

 

Hi. I've have had this rattle for a few months and in desperation, was about to remove the boot/trunk liner. Just by chance I saw that shock absorber top cover had come away and was free to rattle about. Problem solved! I've secured it with some duct tape which will probably last another 5 years. Hope this helps. 

 

NOOOOO!!!!!!!!!!!!!!!!!!!!

 

Replace it and the other side, they are cheap and easy to fit, they are the bump stops for your rear suspension, its doing nothing now meaning the springs are overcompressing which will not only mean you will be grounding out when loaded but their life will be significantly reduced, they will either compress making the grounding even worse or the ends of the coils will break off.

 

They do the above efficiently enough anyway with functioning bump stops.

Oops just seen other posts relating to this. Disregard this one
 

Check the rear shock dust shields are secured with the rubber bump stop. I’ve had these rattle when the bump stop deteriorates and it rattles in the shock housing.

I have also seen plastic inserts left fitted which are used to reduce suspension movement during transport from the factory. One set had been in place for 20000 miles, they just thought the suspension was hard 😳

Edited 19 August, 20205 yr by 3T51704x4