Knocking noise from rear of car
 

Hi all,

I have for a few months now had a knocking noise coming from the rear of the car.

It sounds like it is coming from the rear nearside passenger door or boot space.

It does not knock when travelling along over rough roads at normal speed.

You only hear it at low speed on uneven roads as car sways from one side to the other. So I thought something like a wiring loom or something was flapping around and knocking against a panel.

I have just looked under the car and cannot see anything obvious.

I have shaken the exhaust and that appears to be supported where it should.

The heat shields at the rear don't appear loose, neither are any pipes.

However I did shake the rear wheels in and out and the offside wheel seems to have a little play in the bearing I suspect.

I don't think it is suspension as when I shake the wheel and put my finger on the brake disc and calliper i can feel movement between the two, so the hub is moving.

Would this cause a knock noise?

It obviously was not present at the last MOT 8 months ago as I had no fail or advisories.

There is no rumbling noise when on the move from that wheel that I can detect and no noise under braking.

2005 S60

I too have a mysterious knocking noise/clattering noise from the rear left.

Now, I have just replaced both my handbrake cables, so it could very well be a section of that smacking against the heatshield or body of the car.

Also, the handbrake shoes will rattle if the handbrake cable is not adjust tight enough to take up a bit of the slack, so it could be that but I don't think it is, as I've replaced literally everything on the handbrake mechanism.

I also found that the battery retention bar was completey lose and flapping around in the boot, which did make quite a loud knocking noise, but I've tightened it up and the noise remains.

So I think, it's either handbrake cables, Rear suspension mounts, handbrake shoes or possibly the drop links, but I've replaced those links within the last 9 months so it shouldnt be those (Meyle HD links).

Tad annoying to say the least!

Jack up the back and get both wheels off the floor and then look at the roll bar bushes. A millimeter of movement is enough.

Morning all,

Just driven to work (10 miles, A-Road, Country Lanes) with the radio off and the car has been quiet all of the way, like riding in a Rolls Royce.

The country lanes that I do my last mile and a half are quite uneven with some ruts but nothing from the suspension was heard.

So maybe it is not suspension after all, and the slight play in the offside rear hub is not connected ( there is no noise from the hub, will have it checked at next service).

Will see what noises I get on the way home tonight.

I think I know what's causing my clanking after a bit of googling.

A thread over on the Alfa Romeo forum mentioned that Meyle HD droplinks are known for the nuts undoing themselves very easily because they don't have the nylock thread on them like most droplinks.

The noise that's coming from the back of my car literally sounds like two pieces of completely loose metal clattering together so I'm 100% convinced it must be loose nuts.

I will check this later today and report back.

Well after the quiet ride into work the other day, the journey home was quite different.

On the way home the knocking noise was back again. It sounds like something that is very easy to wobble ie even when I was at a junction and let off the brake to pull away, the minute the neutral-stop came off with its usual small thump there was the knock from the rear of the car.

This is totally unconnected as there is nothing connecting the gearbox to the rear of the car, just the initial small jolt of drive being taken up.

Journey to work this morning..... quiet as usual.

I am wondering if it is something heat related, like trim on the parcel shelf or in the boot as when the car is cold ie mornings its quiet, and when the car is hot ie leaving work after sitting in the sun, I get the knocking noise.

I did find that the rear seat release cables in the boot were flapping around a bit. The nearside one I added a cable-tie and the offside one was not in its plastic retaining clip under the rear shelf.

So we will see later on this afternoon on the way home if anything has changed.

Rear top mounts. Mine knock but only when the car has been driven in the wet.

Hi all,

Think I may have made some progress.

Just been out to the car now that it has cooled somewhat under the bonnet to allow me to poke around.

Bouncing the front of the car I can now hear a clunking noise.

It appears slightly louder when bouncing the nearside front.

I had an assistant bounce the car whilst I felt all the suspension components that I could reach and compare each with the other side of the car.

I can feel a knock/clunk whilst holding front anti-roll bar, I have felt the joint on the vertical linkage that goes up to the shock absorber and I cannot discern any play, neither can I on the top joint.

This is the same for both sides of the car.

Though it does feel slightly more on the nearside.

So there is something happening with the anti roll bar on the front either with these joints or the bushes where its attached to the subframe.

It is a very pronounced "clunk feeling" through the roll bar when bouncing the car.

Think I may have to get expert eyes on it.

I don't think if the roll bar bushes/joints fail the suspension will fall apart?

So I may soldier on until my service and MOT in early August and get them to fix it at the same time.

Am I pushing my luck or safe to carry on for the present time?

Any noise like this, check for broken springs first.

I've had exactly this issue for a while and am pleased to say I've now sorted it. The issue was that the rearmost exhaust mount (right by the tailpipe) had totally rusted through and was allowing the back box to sway and hit the bottom of the car.

One of these fitted and all is well: https://www.ebay.co.uk/itm/VOLVO-S60...72.m2749.l2649