V40: - Random Knocking Noise

rkeegan · Oct 17th, 2016, 21:31

OK I've exhausted all my options so I'll throw it open to the forum. I'm trying to locate a knocking sound that is coming (I think) from the RH front of the car. Volvo 2004 V40 1.8 sport. It sounds like the noise an exhaust makes when not fitted correctly and bangs against the underside of the car. It isn't the exhaust as this was my first check. The knock happens only if the engine drops below idle speed, i.e. when I pull off, or running in first gear and I take my foot off the accelerator. I've changed: the upper RHS engine mount. I've checked all the other engine mounts and no obvious sign of deterioration/witness marks. I've replaced RH drop links and track rod ends, checked the rest of the suspension, checked the anti-roll bar bushes (looking through the wheel arch and from underneath). Checked the CV joints. I've tried bouncing the car up & down and left to right but cannot generate the noise unless I'm driving it. Anybody got any suggestions? Rick

bobthecabbage · Oct 18th, 2016, 08:35

Is it the exhaust?

ITSv40 · Oct 18th, 2016, 09:53

You have changed the RHS drop links etc, but what about the LHS. Although the noise appears to be coming from the RHS, noise does travel through the bodyshell and can sound as if it is coming from a complexly different place to where it actually is.

bobthecabbage · Oct 18th, 2016, 12:55

Is it one knock or a continual knocking sound?

You say it happens when you pull away and when you decelerate?

Also you say it happens when the revs drop below idle but I would have thought the car would be stalling at that point?

I wonder if it is misfueling in these situations and it is actually an engine knock?

I'm not much good with petrols so I'm sure someone more informed will put me right?

pierremcalpine · Oct 18th, 2016, 13:11

how do the control arms look? if your rear control arm bushing was going or if any of the bolts were loose that could certainly generate some noise. I also recall a thread of Gatos's where he suggested that on some vehicles the subframe bolt sometimes comes loose. That is the one that is accessed via the hole in the control arm with an extension on the ratchet. It's a long shot but figured I'd throw it in there. How do the springs look? A broken spring can sometimes be overlooked...Have you checked the brake caliper bolts to make sure they are on tight? A very long shot but make sure that the bearing holder for the RHS axle is on snug. don't overtighten, they are small bolts. Are you getting any vibrations at high speed or does it still feel good?

happy diver · Oct 18th, 2016, 15:40

how's the play in your driveshaft

rkeegan · Oct 18th, 2016, 20:13

OK responses in order:
- May be I'll check the exhaust again!!!
- Checked LH Drop link and it looks OK. I would expect a knock when going over bumps but it's doesn't.
- Knocks irregularly about three or four times. It's a typical knock you get caused by free play in bushes. Nothing like an engine knock. (Petrol or diesel)
- Control arms look OK and checked bolts to ensure nothing is loose but wasn't aware of the subframe bolts so now on weekend check list!
- Springs were also my thought but they all seem OK.
- Calipers are all OK and bolts and sliders correctly fitted.
- Bearing holder, do you mean the one at the top of the suspension? I'll add this to my check list as this would be a good candidate for the noise type.
- Car is fine at speed and far smoother than previous v40
- Play in driveshaft I'm not sure how to check. Done the full lock to lock check in a car park and there is no clicking noise and tried looking for play in the carrier bearing and inner CVs but nothing obvious.
-Thanks for the suggestions so far and keep them coming

pierremcalpine · Oct 18th, 2016, 21:16

Quote:

Originally Posted by rkeegan

- Bearing holder, do you mean the one at the top of the suspension? I'll add this to my check list as this would be a good candidate for the noise type.
-

No, the bearing holder is located midway along the longer axle shaft (the passenger side shaft). It holds the axle in place with a bracket and two screws....it's a very long shot as I think you would get more than just some occasional clunking if this was loose. Bolt 11 in the diagram below.

http://www.volvopartswebstore.com/sh...rimLevel=24674

Gary168 · Oct 18th, 2016, 21:47

I had a similar knocking noise to what you described. Turned out to be the front anti roll bar bushes. Pig of a job to change but with the help of some info on the forum managed to change them and the drop links. Cured the problem. Fitted the poly ones rather than the rubber ones.

happy diver · Oct 18th, 2016, 22:41

(the drivers side shaft)

at full extension check the inner joint for play and wear on the boot

it should make a similar noise, at far less an intensity

Oct 17th, 2016, 21:31	#1
rkeegan Junior Member Last Online: Feb 28th, 2024 21:41 Join Date: Mar 2007 Location: Pontypool	Random Knocking Noise OK I've exhausted all my options so I'll throw it open to the forum. I'm trying to locate a knocking sound that is coming (I think) from the RH front of the car. Volvo 2004 V40 1.8 sport. It sounds like the noise an exhaust makes when not fitted correctly and bangs against the underside of the car. It isn't the exhaust as this was my first check. The knock happens only if the engine drops below idle speed, i.e. when I pull off, or running in first gear and I take my foot off the accelerator. I've changed: the upper RHS engine mount. I've checked all the other engine mounts and no obvious sign of deterioration/witness marks. I've replaced RH drop links and track rod ends, checked the rest of the suspension, checked the anti-roll bar bushes (looking through the wheel arch and from underneath). Checked the CV joints. I've tried bouncing the car up & down and left to right but cannot generate the noise unless I'm driving it. Anybody got any suggestions? Rick

Oct 18th, 2016, 08:35	#2
bobthecabbage Premier Member Last Online: Aug 12th, 2020 21:26 Join Date: Mar 2014 Location: Plymouth	Is it the exhaust? __________________ '04 V40 1.9D

Oct 18th, 2016, 09:53	#3
ITSv40 VOC Member Last Online: Today 12:00 Join Date: Mar 2008 Location: Northampton	You have changed the RHS drop links etc, but what about the LHS. Although the noise appears to be coming from the RHS, noise does travel through the bodyshell and can sound as if it is coming from a complexly different place to where it actually is. __________________ 2001 V40 2.0lt Sport lux - Daily Driver. 174k miles. 2003 C70 2.4 GT Convertible - Garage Queen. 65k miles. http://www.neptuno6benagil.com

Oct 18th, 2016, 12:55	#4
bobthecabbage Premier Member Last Online: Aug 12th, 2020 21:26 Join Date: Mar 2014 Location: Plymouth	Is it one knock or a continual knocking sound? You say it happens when you pull away and when you decelerate? Also you say it happens when the revs drop below idle but I would have thought the car would be stalling at that point? I wonder if it is misfueling in these situations and it is actually an engine knock? I'm not much good with petrols so I'm sure someone more informed will put me right? __________________ '04 V40 1.9D

Oct 18th, 2016, 13:11	#5
pierremcalpine Premier Member Last Online: Jan 3rd, 2024 14:43 Join Date: Feb 2012 Location: Toronto Canada	how do the control arms look? if your rear control arm bushing was going or if any of the bolts were loose that could certainly generate some noise. I also recall a thread of Gatos's where he suggested that on some vehicles the subframe bolt sometimes comes loose. That is the one that is accessed via the hole in the control arm with an extension on the ratchet. It's a long shot but figured I'd throw it in there. How do the springs look? A broken spring can sometimes be overlooked...Have you checked the brake caliper bolts to make sure they are on tight? A very long shot but make sure that the bearing holder for the RHS axle is on snug. don't overtighten, they are small bolts. Are you getting any vibrations at high speed or does it still feel good? __________________ 2003 V40 1.9T B4204T4, 197,000miles (sold but alive!), 2004 S60 2.5T, 160,000miles, 2010 V70 3.2, 125,000miles, 2002 V70XC 2.4, 175,000miles Click here for my x40 and V70 P3 repair guides

Oct 18th, 2016, 15:40	#6
happy diver Active Member Moment Last Online: Apr 29th, 2023 05:58 Join Date: Jul 2012 Location: Brisbane: perfect for one day, asleep the rest	how's the play in your driveshaft __________________ 20,000 leagues under the sea diving to adventure in a silent world with my ceiling the waves...Emile

Oct 18th, 2016, 20:13	#7
rkeegan Junior Member Last Online: Feb 28th, 2024 21:41 Join Date: Mar 2007 Location: Pontypool	OK responses in order: - May be I'll check the exhaust again!!! - Checked LH Drop link and it looks OK. I would expect a knock when going over bumps but it's doesn't. - Knocks irregularly about three or four times. It's a typical knock you get caused by free play in bushes. Nothing like an engine knock. (Petrol or diesel) - Control arms look OK and checked bolts to ensure nothing is loose but wasn't aware of the subframe bolts so now on weekend check list! - Springs were also my thought but they all seem OK. - Calipers are all OK and bolts and sliders correctly fitted. - Bearing holder, do you mean the one at the top of the suspension? I'll add this to my check list as this would be a good candidate for the noise type. - Car is fine at speed and far smoother than previous v40 - Play in driveshaft I'm not sure how to check. Done the full lock to lock check in a car park and there is no clicking noise and tried looking for play in the carrier bearing and inner CVs but nothing obvious. -Thanks for the suggestions so far and keep them coming

Oct 18th, 2016, 21:47	#9
Gary168 New Member Last Online: Feb 26th, 2024 16:36 Join Date: Apr 2016 Location: Salisbury	I had a similar knocking noise to what you described. Turned out to be the front anti roll bar bushes. Pig of a job to change but with the help of some info on the forum managed to change them and the drop links. Cured the problem. Fitted the poly ones rather than the rubber ones.

Oct 18th, 2016, 22:41	#10
happy diver Active Member Moment Last Online: Apr 29th, 2023 05:58 Join Date: Jul 2012 Location: Brisbane: perfect for one day, asleep the rest	(the drivers side shaft) at full extension check the inner joint for play and wear on the boot it should make a similar noise, at far less an intensity __________________ 20,000 leagues under the sea diving to adventure in a silent world with my ceiling the waves...Emile

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