Clonk.

[lynns hubby]

We have had an annoying Clonk type noise coming from under our 2006 XC70 I have been looking for it for the last few weeks. I have narrowed it down to the front of the car as if you drive over a speed bump the noise can be heard before the rear goes over the bump.
It sounds like a metal to metal type of clonk. at first I thought it could be a roll bar end link but having checked both sides they are fine. (I had replaced them around 9 months ago but some wear out quicker than others). The noise has gradually got louder over the last couple of weeks. I have checked the ARB bushes which are fine with no play. I have checked every bush I could find and still found nothing of concerned. I have changed BOTH wishbones around a month ago so the bushes are good on them. I have had the wheels of the ground and a big bar under each front wheel and got my mate to wiggle the bar up and down and can find NO play anywhere.
I have checked the driveshafts both sides for play and can find nothing. Checked the driveshaft bolts for tightness in the hubs, both sides are tight.
It had its MOT last week so I mentioned this before hand. It passed with an advisory for the rear ARB bushes or pin slight play but not worn to excess.
I did check them out and there is the smallest amount of movement but nothing to suggest the noise I am getting which I have eliminated to the front anyway.
Looked again the other day and the offside front driveshaft has a slight amount of lateral movement, I would say around 0.5 mm aprox. If I move it sharply it does make a knocking noise. The movement appears to be the shaft sliding into the joint at the internal splines as opposed to any movement in the joint itself. The N/S shaft does not seem to have any play, or at least nothing I could detect.
Should there be any significant play in the driveshafts where they go into the joint ? I understand that the length from gearbox to roadwheel will alter as the vehicle is driven over various surfaces via the suspension but that is the job of the CV Joints to allow for this.
Any suggestions welcome.

[stuart bowes]

my clonk when i had one was similarly difficult to locate, checked all the same things but it turned out to be balljoints

I had also recently changed the wishbones and it wasnt obvious at the time

it also wasn't obvious with everything bolted together, presumably because it's under so much tension. but as soon as I disconnected it the bolt end flopped about loose as anything and it was glaringly obvious

I may have overtightened them when replacing wishbones and killed them off. Not sure but now I always torque them correctly

may or may not be the same for you

[lynns hubby]

That's interesting Stuart. I did change the N/S balljoint when I changed the wishbone as it was, like yours, flopping about. However the O/S balljoint seemed fine with the expected resistance in all planes.
Not an expensive item to change if I find nothing else but I was comfortable that it was still serviceable and it is showing NO signs of excessive movement.

Thanks
Malcolm

[john493]

The common causes are loose centre bolts holding the driveshafts into the hub - renew these bolts with genuine Volvo and angle tighten to spec - they are single use bolts.
Also ball joints are Stuart mentioned - not easy to test without the lower arm off. Have you got steel or alloy lower arms ?

[Dancake]

Check your calipers. Make sure the slider pins are tight, the caliper carrier bolts are secure and the retaining springs are in place. Loose slider pins will give a metallic rattle/clonk over rough surfaces.

[Georgeandkira]

How many miles are on your '06?
Maybe a strut element is weight/speed bump related? Struts themselves can make an array of sounds and a bearing mount could have separated somehow. That'd be metallic in sound.

A rear suspension arm bushing?

Something touching the center driveshaft?

[lynns hubby]

I have got alloy wishbones. I have checked Both centre bolts fot tightnes and both are OK.
Will check out the brakes again when I get home.
It has got around 117,000 miles on it so barely run in.

[Thassos]

have you had a look around the rear exhaust box, the outer skin can rust thru, and as i recently found the last hanger on the tailpipe on mine had corroded away then youll get some random clunks as the box moves around too much.. always worth checking , the rear hanger is an easy fix with this part

http://https://www.ebay.co.uk/itm/VO.../284786853794?

[lynns hubby]

Originally Posted by Thassos

have you had a look around the rear exhaust box, the outer skin can rust thru, and as i recently found the last hanger on the tailpipe on mine had corroded away then youll get some random clunks as the box moves around too much.. always worth checking , the rear hanger is an easy fix with this part

http://https://www.ebay.co.uk/itm/VO.../284786853794?

That was the first place I started as, like you, I have had issues with exhausts in the past.
Everything is fine there. I even thought that maybe something broken off inside the exhaust but no amount of shaking or banging on the exhaust can replicate the noise I am getting.
I am certain its from the front as if I drive slowly over a speed bump, it clonks before the rear wheels have been anywhere near the bump.

[Thassos]

Drop links can show that kind of clunk, but thats probably too much of a simple answer, its hard to really pry suspension joints, but maybe try disconnecting one end of a drop link and try the speed bump test, although last time i tried undoing mine the nut wouldnt budge and broke the smallish torx bit (so some pre soak might be needed), the drop link setup on the P2 seems pretty chunky and still holding up well at 150k, the other idea it might be a track rod end i had one of those go some miles back.. sods law says itll be the most unlikely culprit when (or if) you do find it,