Idle noise which goes when accelerator is pressed

Yetibeard

Yetibeard

Member
T6 Pro
Hi, can anyone help diagnose this issue? There is a noise when the engine is on idle (cold or warm), but the noise goes when the accelerator is pressed, but then comes back when the revs return to idle (see video). Belt tensioner has been replaced so it isn't that. The noise is like a rattle/vibration. Pressing the clutch in doesn't change the noise. Its easier to hear inside the van, and I think I can hear it better from the drivers wheel arch than the passengers. Some googling suggests it could be the dual mass flywheel? could this be right? Any help at all is greatly appreciated!

T6 T30 manual 6 speed blue motion highline 66 plate (2017). full service, 54k miles

 
That seems very noisy outside, especially by the wheel. Dual mass flywheel issue maybe?
 
Does it still rattle if you put it in gear at idle and gently lift the clutch until it just starts to engage? Personally I think it sounds the wrong frequency for the DMF.
 
The Bear78 said:
Does it still rattle if you put it in gear at idle and gently lift the clutch until it just starts to engage? Personally I think it sounds the wrong frequency for the DMF.
Click to expand...
Ill take a video tomorrow.
So you mean, put it in 1st and just gently lift the clutch and let it engage without and additional accelerator?

Do you suspect something else?
 
Could be loose exhaust heat shield….resonating at idle
 
Yetibeard said:
Ill take a video tomorrow.
So you mean, put it in 1st and just gently lift the clutch and let it engage without and additional accelerator?

Do you suspect something else?
Click to expand...
Yes, that's what I mean. Lightly load the transmission while keeping revs in the noisy range and see if it is still noisy.
For your own sake, I hope I'm not barking up the wrong tree but it does sounds a little too rattly to me.
 
I had exactly the same symptoms, but the noise was much quieter. That was DMF which I got replaced under warranty by VW.
Has the noise just appeared or has it got progressively worse to where it is now?
May be just a more advanced state of knackered DMF.
Get it checked. I drove my A4 until the DMF let go and it took out the starter motor and gearbox.
 
Bigsidavies said:
I had exactly the same symptoms, but the noise was much quieter. That was DMF which I got replaced under warranty by VW.
Has the noise just appeared or has it got progressively worse to where it is now?
May be just a more advanced state of knackered DMF.
Get it checked. I drove my A4 until the DMF let go and it took out the starter motor and gearbox.
Click to expand...
I think it’s got a little worse but I couldn’t say that for 100%.
Just out of interest, what specifically makes the DMF go like this? Has something broken on it?
I will get it checked out as soon as I can
 
The Bear78 said:
Lightly load the transmission while keeping revs in the noisy range and see if it is still noisy.
Click to expand...
Right, so I done this a few times. The video below is with the window down. I don't press the accelerator until after the 2nd start but you'll see this on the rev counter. It seems like the noise stops (or goes really quiet) initially during the contact but then comes back when the clutch is fully out.

 
Right so I can see a belt from the drivers front wheel arch which is a bit loose when on idle, but gains tension on acceleration. What is it!
 
Yetibeard said:
Right so I can see a belt from the drivers front wheel arch which is a bit loose when on idle, but gains tension on acceleration. What is it!
Click to expand...
That’s the auxiliary belt, so from what I’ve read on previous cases it’s the tensioner bouncing causing the noise.
If this belt breaks it can foul the cambelt and that gets expensive.
 
(Please excuse my ignorance!) The part number I've had changed recently is 03L903137H, is this the same belt that hasn't been tension correct, or is it a different belt?

Thanks all.
 
Yetibeard said:
(Please excuse my ignorance!) The part number I've had changed recently is 03L903137H, is this the same belt that hasn't been tension correct, or is it a different belt?

Thanks all.
Click to expand...
@Yetibeard
That part number is a ribbed belt which can only be the auxillary belt. If you have just had it changed I suggest you contact the people who changed it.
There was a recall for the automatic tensioner but that was started years ago so perhaps you haven’t had your van serviced for years or possibly not by VW or a VW specialist otherwise it should have been picked up before.
Have a search on the Forum
 
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