2007 Polo 1.9TDI - clunking noise during deceleration /acceleration at low speeds und

[JITHEN]

Guys in the last week or so I am hearing a clunking sound when I take my foot off the accelerator while driving and accelerate again. The noise manifests itself at lower speeds below 40kmph while either accelerating or decelerating and then vanishes as speed builds up.

The car has run 111200kms.
What could be the problem at hand?
Your advice would be greatly appreciated.




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[h100vw]

Guys in the last week or so I am hearing a clunking sound when I take my foot off the accelerator while driving and accelerate again. The noise manifests itself at lower speeds below 40kmph while either accelerating or decelerating and then vanishes as speed builds up.

The car has run 111200kms.
What could be the problem at hand?
Your advice would be greatly appreciated.


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Hard to diagnose a noise you can't hear.

Can you feel the clunk in the floor at all. My Favourite things to check would be the rear LCA bushes. They are rubbish and fall apart when you look at them. The arm can move around and hit the housing.

Otherwise engine mounts, ball joints, track rod ends would be my next points of interest.

Gavin

[kaanage]

Anything like what's described in these threads?

http://www.vwwatercooled.com/forums/f127/clunk-when-transitioning-engine-driving-engine-braking-off-throttle-63539.html

http://www.vwwatercooled.com/forums/f127/knocking-when-transitioning-off-light-throttle-90293.html?highlight=

[JITHEN]

Hello Gavin and Kaanage. Thank you for your inputs.
1. No I cannot feel the noise through the floor or through vibrations thru the 3pedals. Braking action is smooth with no vibrations through the wheels or steering wheel.

Today I emptied the car of all items in glove box side pockets and boot and commenced my 32 kilometer one way journey into the city which is my daily routine. The following observations were made.
1. Starting the car and leaving home I noticed a mild clunk noise when taking my foot off the accelerator, as journey progressed this sound did not manifest itself during the transition between acceleration / deceleration.
2. Approximately half n hour into the journey while applying brakes I noticed a distinct clunk sound, which now appeared quite a few times when the brakes were applied.. The sound looked like something was making contact against another part. No vibrations were felt through the brake pedal or steering when this clunking sound was made.
It's interesting that today this sound took nearly half n hour of motoring to materialize. I get the feeling the sound is coming from the rear underbody.

Based on the above symptoms what in your opinions could be the problem??




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[Umai Naa!!]

Pull everything out of the spare wheel well, and go for a drive.

Also, you do hear the fuel slosh around a bit when it's getting low, as the tank is plastic, and right up under the rear seat.

[JITHEN]

Fuel slosh yes I do hear that every now n then. Ok will remove the spare wheel tomorrow n drive to work.


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[Ryeman]

Surely not simply brake pads 'rocking' because they are v slightly loose in the slots.....just a thought.
That would be quickly eliminated by creeping forward and then 'tapping' the brakes and then the same in reverse.
Was there any recent brake maintenance?

[JITHEN]

The brakes -rotor/pads were replaced at 93000kms.
Will try the procedure you mentioned re: brakes tonite.

Interestingly today on the way to work the clunk noise while pressing the brakes did not materialize half n hour into the journey. They was a slight click/clunk noise during the acceleration / deceleration phase. This noise occurred on a few occasions.

Will monitor the car the coming week n see how it goes.


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[Ryeman]

I haven't seen the setup but wonder if a pre-load spring/shim is missing.

[JITHEN]

Tried the fwd/reverse movement with braking actions. No noise noticed at all.


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[Ryeman]

Well that would seem to eliminate quite a few things incl some suspension links.
Original minis had a torque reaction link tying the top of the engine to the firewall.....is there anything similar?
Could engine torque cause the exhaust to 'knock'?

[JITHEN]

Being a Diesel engine torque related vibrations should manifest even at idle. Had a look at undercarriage at idle did not notice any exhaust vibrations.
However during today's journey into work saw the clunk sound arise around 50 mins into the trip while braking. Will have to get the vehicle on a hoist n have the engine underbody cover removed and have all exposed components examined. In the engine bay during idle the vibrations are normal and no untoward vibrations noticed.


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[JITHEN]

I have a feeling this noise that arises during braking is temperature related?? This is because at night during my journey home this clunk sound while braking does not arise at all.


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[Umai Naa!!]

How about upper rear shock mounts?

[JITHEN]

Will have to get them checked, I'll have a look tonite with the help of a flashlight.


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