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Occasional, metallic knock at low speed at rear

Posted: Wed Oct 11, 2017 9:17 pm
by fat controller
I have gone into this on the thread about the battery warranty, but thought I would put it in a thread in its own right, if only to make sure that it is not missed by being buried in among all the battery stuff.

I have a low speed ( <15 mph) knock from the rear of the car; to my ear, it sounds metallic and almost hollow, and is not all that loud, but it is noticeable. I think it is more to the nearside of the car, but hard to tell - and it definitely sounds as though it is coming from under the car (so, not something up in the headlining or anything). Anyone who has had the vibrating airbox problem - to give an idea, it isn't as noisy as that.

I took my neighbour out a spin earlier, and although it took a while to show, he did hear it and his thoughts were exhaust, heat shields, a pipe (fuel/brake) or maybe a drop-link on the rear suspension if it has them. I had a look myself last week (admittedly the car wasn't raised) and the only thing I could find that moved underneath was one of a pair of pipes, with 90º bends in them which I believe are fuel pipes (too big to be brake pipes in my opinion).

I have done a bit of searching, and turned up not very much - one thing that I did read (cannot remember where now) was to take up the back seat base and apparently there is some sort of brace under there that whilst it isn't "loose", is isn't as tight as it could be - - the advice is to give it a nip up?

So, over to you ladies and gents? Any ideas? And if it is this brace under the back seat base, does the seat base come out easily?

It is likely that we will get the car up on stands at the weekend and have a look to see what we can find, and of course whatever we do discover will be posted back here hopefully to help others in future.

Re: Occasional, metallic knock at low speed at rear

Posted: Fri Oct 13, 2017 2:02 am
by RoadKnight
This sounds suspiciously like the problem I was encountering and described on this forum a month or so ago - an intermittent ticking or clicking noise that was emanating from the rear of the car somewhere.

I returned it to the local Nissan dealer who to my surprise took it very seriously and their immediate response was to fit a Nissan-recommended body stiffening kit ("Nissan Technical Bulletin BT17-001 on J11 Qashqai Body Creaking noise from rear"). The service manager said that there is a lot of flex in the QQ bodies, especially the ones with pano roofs.

This fix almost eliminated the noise, however after a couple of weeks it was back and much worse than ever - especially at lower speeds than before.

They pulled it all apart again and claimed to have tightened every nut and bolt under the car rear and in the roof area - after removing the roof lining again. The manager seemed to think that the bolts attaching the roof rails may well have been the main culprits.

The noise is now completely gone, however I am concerned that it is going to return, especially if the body flex is going to gradually cause nuts to work loose - and maybe welds to also be impacted.

So I'd recommend taking it to your dealer and insisting they fix it. And if they are not responsive, I would escalate it to Nissan.

Re: Occasional, metallic knock at low speed at rear

Posted: Fri Oct 13, 2017 7:03 pm
by fat controller
Thanks - it is not a creaking noise on mine, but more of a 'dink' sort of noise - I am wondering if it is the issue where the brake pads are moving up and down within the caliper, as it is the sort of sound I could imagine that making. Wouldn't be surprised, as the caliper is on the 'wrong' side of the wheel - as the wheel rotates, the movement could lift the pad (particularly if it hasn't fully released back from the disc) and the all that is available to it is to come back to rest with a clunk.

I am tempted to pop a wee smear of copper ease on the sliders of the caliper and see if that solves it.

Failing that, it is in for service next week, so I will speak to the dealer.

Re: Occasional, metallic knock at low speed at rear

Posted: Sat Oct 14, 2017 5:53 pm
by switchback
Is it the the well known rear axle problem? Lots have been replaced.

Re: Occasional, metallic knock at low speed at rear

Posted: Sat Oct 14, 2017 6:15 pm
by fat controller
I am hoping not - surely if it were the rear axle, it wouldn't have passed an MOT?

Re: Occasional, metallic knock at low speed at rear

Posted: Sun Oct 15, 2017 4:08 am
by RoadKnight
I wouldn’t be so sure it is not body flex. My noise was also a click or dink sort of noise - not unlike a small stone being thrown up by a wheel against the wheel arch. I would imagine that body flex noises could be quite diverse in their manifestation.

If no other obvious source of the noise can be found, then I think you would have to assume body flex - especially as this is a known problem in these vehicles. And Nissan has issued a body stiffening kit to address the problem. Presumably as this is not a safety related issue, it is only fitted when customers complain of strange noises from the rear of their vehicles.

Re: Occasional, metallic knock at low speed at rear

Posted: Sun Oct 15, 2017 9:31 am
by gvmdaddy
Where exactly does this body stiffening kit get fitted? How much work is involved?

Re: Occasional, metallic knock at low speed at rear

Posted: Sun Oct 15, 2017 7:05 pm
by fat controller
Any idea of the cost of the stiffening kit?

Re: Occasional, metallic knock at low speed at rear

Posted: Sun Oct 15, 2017 9:46 pm
by RoadKnight
As previously mentioned the stiffening kit is covered by a technical service bulletin from Nissan (BT17-001 on J11). It is to address noises caused by flexing of the body. If the vehicle is under warranty and it is making noises from the rear, then I would imagine Nissan would fit this at no cost.

I had to leave the car with them for a couple of days, so I imagine it was quite a lot of work. It apparently involved removing the roof trim, fitting brackets as well as introducing a gap between the rear panels and re-mounting the rear door.

There are no obvious changes, other than the rear door seems to be sitting a little differently and now fits much more snugly than before - and needs a firmer slam to close.

Re: Occasional, metallic knock at low speed at rear

Posted: Sun Oct 15, 2017 11:23 pm
by gvmdaddy
RoadKnight, I’m wondering if you’ve been spun a yarn by your service manager.
BT17001 may not be a Nissan Bulletin, but it is a product name of a Copper Paste that is used to prevent squealing and creaking of touching parts. Sounds to me like they’ve possibly applied this to your brakes. It would be interesting to see what this so-called stiffening kit comprises of if it does actually exist. Seems doubtful to me.