Whirring/grinding noise on light acceleration

[wkd33]

Hi all, I'm new to the forum and have signed up in the hopes one of you fine people can help me diagnose this ongoing, mysterious low pitched grinding noise which I'm increasingly concerned will soon culminate in a loud bang.

Background: car (184 TDI, 6-speed manual) is on 55k miles, has been remapped stage 1 for 5k of those, noise present last 1.5k miles.

It emanates from the middle of the car around the front footwells when cruising in gear or lightly accelerating, mostly between 1.5k-2k revs and stops as soon as you engage the clutch and throw it into neutral, not without first becoming momentarily louder for a split second as the clutch engages. It happens mostly around 30mph tootling around town. No noticeable clutch slip or judder through either pedals. 2 independent garages have said there's nothing wrong after driving it for 10 mins and failing to replicate the sound - no wonder they believe that: It's quite easy to avoid the sound if you're always on the gas pedal at least 20% and above 2k rpm. Sound does not change or worsen upon turning either direction. It is worsening slowly as time goes on, becoming louder and more frequent.

 

[SuperV8]

Is it only in certain gears? or any gear?

Has it ever had a gearbox oil change? probably the cheapest option first.
Grinding noises in your gearbox are not good though - so maybe a gearbox bearing issue?

 

[wkd33]

Is it only in certain gears? or any gear?

Has it ever had a gearbox oil change? probably the cheapest option first.
Grinding noises in your gearbox are not good though - so maybe a gearbox bearing issue?

Worst in gears 2,3,4 but audible still in 5&6. I don't recall hearing it in 1. Can be loudest in 4th gear.

I've already committed to a gearbox oil change this week as I'm putting on 4 new corners worth of brake discs and pads, so that's a good shout. Shouldn't cost too much either. I'll report back.

Today, I'm taking it to the garage who mapped the car to see what they think. I have a warranty with them so I may have some luck in recouping potential repair costs.

 

[wkd33]

Update: I took my car to the guy who remapped it back in February and while the noise was being shy for the most part, it was loud enough at times to give an accurate picture of what I've been hearing. He wasn't certain but he believed it could be the turbo vanes getting stuck/malfunctioning when the throttle is being pressed ever so slightly.

Would this explain why the noise is harder to initiate reliably and why, once it begins, it stays until about 2.2k rpm? He thinks it's benign for time being, but it's been getting worse past month.

I'm getting a bottle of revive diesel turbo cleaner to see if that helps ameliorate the issue.

 

[Olivero]

Hi
I have a 5F 1.4tsi manuel

And im experiencing the exact same thing, it doesnt effect the driving or anything the peddals dont rattle or even the stick doesnt. And I am getting more concerned as to what it is and how am I gonna have to repair it

I myself have been to my garage and they couldn't find any conclusion as to what it is, my best guess is, if you open the hood and try to rattle with the whole transmission assembly by hand, you are able to do so with no special force, and im guessing as one is in lower rpm it just starts to vibrate and cause this noise, yet i still dont know how to solve this issue ?

do you think the transmission oil change did anything or no ?

 

[wkd33]

Hi
I have a 5F 1.4tsi manuel

And im experiencing the exact same thing, it doesnt effect the driving or anything the peddals dont rattle or even the stick doesnt. And I am getting more concerned as to what it is and how am I gonna have to repair it

I myself have been to my garage and they couldn't find any conclusion as to what it is, my best guess is, if you open the hood and try to rattle with the whole transmission assembly by hand, you are able to do so with no special force, and im guessing as one is in lower rpm it just starts to vibrate and cause this noise, yet i still dont know how to solve this issue ?

do you think the transmission oil change did anything or no ?

Not as far as I'm aware. Gearbox seems in good condition. I'm willing to bet my turbo vanes/actuator is sticking/faulty or there is some loose piping prior to entering the turbo.

I'll do the diesel revive tonight and update if that helps. On the plus side, new brakes discs and pads are feeling lovely and no more squeaking! Another £500 down though

 

[SuperV8]

Hi
I have a 5F 1.4tsi manuel

And im experiencing the exact same thing, it doesnt effect the driving or anything the peddals dont rattle or even the stick doesnt. And I am getting more concerned as to what it is and how am I gonna have to repair it

I myself have been to my garage and they couldn't find any conclusion as to what it is, my best guess is, if you open the hood and try to rattle with the whole transmission assembly by hand, you are able to do so with no special force, and im guessing as one is in lower rpm it just starts to vibrate and cause this noise, yet i still dont know how to solve this issue ?

do you think the transmission oil change did anything or no ?

The 1.4tsi has common turbo actuator rod rattling.