XC90 T5 Strange clunk/pop sensation (updates with sound file)

[peteski2022]

Hi all,

I’m looking for some advice please as this is driving me crazy!

My T5 XC90 has developed a rather odd noise that neither I (nor Volvo) it seems can locate.
I’d describe it as a bit of a popping clunk most noticeable at low speed.

It happens at various times and creates varying degrees of noise and sensation.

When completely stationary, the noise alone occurs very slightly when putting the car into reverse (not convinced it isn’t happening when put into drive but less sure). The noise is relatively faint and sounds like a bit of a light tap/clunk sound that to me seems to come from deep inside and around the gear selector (is that where the transmission or any moving parts of it are?)

During low speed (5mph) (straight line driving and no steering wheel input) by very lightly lifting on and off the accelerator (barely giving any throttle) so not to notice any significant pick up by the car I get the tapping knock that coincides with me coming on and off the accelerator.

Under braking, I get a real clunking sound felt through the pedal and a sensation of something mechanical almost feeling like its releasing and slightly shifting causing a brief stuttering sensation. Other than the sound which you can hear the sensation you get of the stutter isn’t really noticeable unless you are the driver but something definitely doesn’t feel right. Then when lifting off the brake and beginning to accelerate a slight clunk/pop sound again but no stutter.

We’ve ruled out anything loose as the car doesn’t make a sound going over speed bumps or potholes.
It's been into Volvo and the mechanic who test drove it with me could hear and feel the car doing it and felt it was suspension related. They changed an offside rear ball joint and related components which they felt had play but it’s done absolutely nothing.

I know nothing about cars and wouldn’t know what the cause could be so any advice would be massively appreciated. I can’t understand how the noise can be created just by popping the car into reverse when stationary and at the same time create a more pronounced clunk coming on and off the accelerator lightly and a more pronounced thunk and sudden and exceptionally brief grabby stutter sensation under braking.

Thanks guys!

[AVOIT17]

If we start with the following observation:
"Under braking, I get a real clunking sound felt through the pedal and a sensation of something mechanical almost feeling like its releasing and slightly shifting causing a brief stuttering sensation."

It could be something from the brake system or with the suspension/subframe bushings/engine mounts system.

And one question here: the clunking sound is it a 'single' clunk or multiple? If multiple are they rhythmical?


You mention the following:
"When completely stationary, the noise alone occurs very slightly when putting the car into reverse"

Here as well I would ask about the noise is it a 'single' clunk or multiple? If multiple are they rhythmical?


You also said:
"During low speed (5mph) (straight line driving and no steering wheel input) by very lightly lifting on and off the accelerator (barely giving any throttle) so not to notice any significant pick up by the car I get the tapping knock that coincides with me coming on and off the accelerator."

This would point to the suspension/subframe bushings or engine mounts.

[peteski2022]

@avoit17 It could be something from the brake system or with the suspension/subframe bushings/engine mounts system. Volvo visually inspected the car and found a ball joint needed replacing but that was all they could see suspension wise. As far as the engine mounts go I highly doubt they checked so good to know thanks - how may are there and how easy are they to see?

And one question here: the clunking sound is it a 'single' clunk or multiple? If multiple are they rhythmical? Putting the car into gear (reverse if last driven forwards, or forwards if last driven in reverse) creates one relatively faint popping dunk noise. Driving, in the final stages of slowing down creates either one/two or three louder dunking pops usually first louder than second or third. Never a pattern and not rhythmic. Always in the final moments of braking say to slow for speed bumps.

You also said:
"During low speed (5mph) (straight line driving and no steering wheel input) by very lightly lifting on and off the accelerator (barely giving any throttle) so not to notice any significant pick up by the car I get the tapping knock that coincides with me coming on and off the accelerator."

This would point to the suspension/subframe bushings or engine mounts. Thanks will ask Volvo to check these

Does the transmission bolt to anything and can that cause noises like this?

Is something in the transmission creating the noise do you think?

I've uploaded a zip file of the sound being made when the car is placed into gear. The noise is the very final sound at the 5sec mark - all other noise is me putting the car into reverse (having previously been driven forwards).

[AVOIT17]

The sound on the audio file ... I hear 4 fast clicks in a row at the end of the recording... that did not sound like your description... Is that what I was suppose to hear?

Yes ...the transmission usually has also mounts with rubber bushings that can wear out and fail.

[peteski2022]

Hi so the quick clicks at the start are me putting the car into gear. Its the very final lower sounding bop knock noise that is the actual noise that the car makes. Thanks!

[AVOIT17]

Hi so the quick clicks at the start are me putting the car into gear. Its the very final lower sounding bop knock noise that is the actual noise that the car makes. Thanks!

I see... From the recording there is not much I can tell. From your descriptions it points possibly to a deteriorated bushing.

Which bushing/mount? This is a question of diagnosing and eliminating the possibilities. Diagnosing for bad bushings can involved a lots of different methods.

In my experience when there is a sound caused by a bad bushing, it means the bushing is in bad conditions and therefore is more easily identifiable

If you are bringing it to a Volvo mechanic, he should be able to diagnose this.