Knocking Mystery! help :(

[pointer7]

First time poster here so hi

I need some advice as I am about to pull what's left of my hair out, I have a 2014 Volvo S60 which has had a knock on the N/S/R for nearly a year.

It's had new shocks both sides, new drop links, a spring and top mount but the noise is still there! its over uneven surfaces where it knocks on just the nearside even at very slow speeds (crawling speed!)
I have been told that I could have been unlucky and got a bad new shock with a "dead spot" in it is this possible? I tried all other possibilities, driving with the seats down, removing the boot floor and the tool kit just in case & the Exhaust has also been checked.

Other than trying another new shock, what else can it be mechanically!?

Thanks in advance

[GreenV8S]

Get the car up in the air and give every component you can see a good pull to see if you can persuade any of them to make a noise similar to what you're hearing. It could be coming from any component attached to the car or its suspension so look at exhaust, transmission, fuel tank etc as well as the suspension.

[E-bmw]

Instead of just firing parts at the car & hoping to accidentally fix it, why not get under the car & find the issue?

Get it up above ground level with the weight on the wheels (ramps are ideal for this) and use a prybar to move things around you should find the issue.

[pointer7]

Thanks for the advice all...

I did forget to mention that it's been to 3 different garages and they all said they can find nothing wrong. I have jacked it up and can find nothing, I'm just doing what all the other garages have been doing.

I have even checked if the bumper is loose, number plate loose, tailgate etc but nothing even the rear passenger door I have adjusted but no difference

[GreenV8S]

Given that it happens at very low speed, it might be worth having somebody drive it slowly over an obstacle such as a plank of wood while you listen from outside. That might give you more insight into the location of the sound.

[HealeyV8]

Have you looked at things like handbrake cable / mechanism, fuel lines, brake lines etc?

[tones61]

tighten driveshaft nut .had same a couple weeks ago at work :-)

[Fastpedeller]

Anti-roll bar links? We had this on a brand new Fiat. The noise was there over low-speed surface irregularity and sounded like 'under the dash'. I elected to not mention to the main dealer (as I didn't was the dash removed and the resultant more rattles due to broken clips). I was confident it was nothing serious/dangerous, just irritating. Found play in links, replaced them, never had the 'problem' again.

[pointer7]

Thanks all for the suggestions...

Its quite a clunky knocking noise so i'm not sure if it will be handbrake cable related but will check.

The car has had drop links both sides and I mentioned anti roll bar links to the last garage it went to and they said drop links are the same thing?

I'm still erring towards a dodgy shock absorber....

[E-bmw]

pointer7 said:

I'm still erring towards a dodgy shock absorber....

If that is what it is, as I said earlier you should be able to find it from underneath rather than just fitting sh!t to it in the hope of fixing it.

[pointer7]

The shock doesn't show anything wrong visually (no misting or unusual bounciness) but I was told that they can have a "dead spot" even on a new shock which would also cause a knocking sound...

[GreenV8S]

pointer7 said:

I was told that they can have a "dead spot" even on a new shock which would also cause a knocking sound.

Perhaps that's a reference to an air lock, but I'd expect any production shock to be self bleeding.

[Fastpedeller]

Hope after all this expense the OP doesn't find it's the spare rattling in the boot

[E-bmw]

pointer7 said:

The shock doesn't show anything wrong visually

I am not talking about seeing anything wrong.

If there is a knock when the suspension moves all you need to do is (using leverage & prybar) replicate that motion & listen for what knocks...…. Simples!

On top of that, I have never heard of a shock having a "dead spot".

It could be that he is talking about internal backlash, but I have never heard of that either.

Edited by E-bmw on Friday 14th February 13:45

[pointer7]

I hope it isn't the spare rattling because it doesn't have one lol..

Once the weather improves I think I'll have to get underneath again and have a good poke around

[Grayedout]

Don't know the suspension setup but are the springs and shocks separate? If so you could remove both shocks and then drive the car for a very short distance to see if the noise is still there.

Got a similar noise on my Honda and did the above to rule out the shocks. Still not found the problem but at least it's something else off the list !

[pointer7]

I think it might well be the shock...

I have started to notice that on very cold mornings, the knocking is very minimal and the further I get in to my journey, the knocking then starts?

Do shock absorbers “warm up”? waiting for some better weather to jack the car up and scramble underneath

[frye]

I know your pain. I had a similar issue with my car (astra H), same thing also happened with me when I took it to the garage to investigate.

I had replaced both top mounts and drop links as everything else was ok underneath and yet the noise persisted. Anyway by chance I had to take my car into another garage for a new exhaust and ask them on the side to investigate the noise. Basically one of the top mount had collapsed (even though was supposed to be new) which then ever so slightly took out the cheap droplink that the previous garage had also fitted.

A new top mount and droplink plus tracking and no noise. Feels weird now having such a quiet car.

[pointer7]

Hi All,

Sorry to resurrect this thread but seemed silly starting a new one!

Over the last few months, the first lockdown gave me time to sort a few niggles with my car that normally get put off (interior squeaks, sorting a few scratches on the bodywork etc.)

Once the lockdown was lifted I booked the car in for a service with my usual guy who said "is it still knocking" to which I replied "yes like a bugger" so he has had another look at it.

I went to pick it up and he had left it on the ramp to show me underneath, the top mount is rock solid, the new drop links are fine and the shocks are only a year old but again, its a complete mystery.

Does anyone have any other ideas?

[ReverendCounter]

Could there be a tool/socket/toolset inside the bodywork, behind some trim somewhere? I was also going to suggest fuel tank but that's been mentioned. Exhaust + hangers all OK? Are the wheel nuts tight? Brake callipers OK?