Hello, fellow Briskodians ...

Before I run off to the invariably brilliant but always busy Unit 18 in Milton Keynes, I have an irritating sound that's appeared and I can't decide if it's serious or just that - irritating and no more.
It's a bit odd in that it doesn't line up exactly with anything I've seen or read about before.

The best way I can describe the noise itself is like a belt tapping the inside of a housing, or maybe a set of slightly loose bolts that secure a part & let it rattle against something else ... it's not a harsh rattle and I don't think, tappet / valve lifter noise.
More like meshing noise on a chain ...

So, I'll do my best to describe how it occurs:

The car normally idles when warm at about 800rpm, normal idling noise, in gear clutch in, or in neutral, clutch in or out. Idle is smooth, no "lumpiness".
Increase revs to maybe 950-1000, the noise starts. Go beyond about 1100rpm, the noise cuts off quite abruptly.
The noise is there with the car moving at very low revs (creeping in traffic) and only cuts off once that 1100rpm-ish threshold is reached.
If I put the clutch down and let the revs drop, they only drop, as long as the car is rolling, to about 1000 or so & the noise occurs as the revs drop through about 1100, then persists until I bring the car to a very close to, or actual, stop. Only when I am at a full stop (or v close to) do the revs fall to "normal" idle of 800 and the noise disappears.

Originally I though it could be the DMF - but it's a relatively new clutch (45k miles or so) and it doesn't appear to matter whether the clutch is in or out - which also (I think), removes a worn thrust bearing as a possibility.
I wondered if it was the swirl flap actuator but IIRC, the swirl flap actuation was mapped out some time ago, before the new clutch went in & this issue has only been happening for (maybe) 3000mi (I do a lot of miles).
Current car mileage is 217k, mostly (since I bought it at 90k) motorway / autoroute / autobahn.

Open to ideas before I hand the keys of my piggy bank to Ali, Adam & the boys at U18 ...

Thanks all!

Edited 28 August, 202528 Aug by gfkskoda
Plate

Damn, just seen this is in the wrong forum and I can't see how move it or even if I can - will re-post on Mk 2 Forum.

14 hours ago, gfkskoda said:

I can't see how move it or even if I can - will re-post on Mk 2 Forum.

Asking Administrators to move this discussion.

Had similar noise on my mk2 octavia. Weird almost high pitch rattle but only at certain low revs. Eventually tracked it down to the heat shield above exhaust under car that had dropped as the fixing push on securing washers were rotten. Reckon at certain revs it hit resonant frequency and rattled. Used some cable connector strips to screw onto fixings stubs to wedge it up again.

I'll check that - TY!

Re Title,

Is it a 2.0 TDI ?

the turbine actuator lever on the axles has air for sure, it can rattle like that, there are fuses that secure it so it doesn't rattle.

On 29/08/2025 at 13:05, gfkskoda said:

I'll check that - TY!

On 29/08/2025 at 13:10, Guest_ said:

Re Title,

Is it a 2.0 TDI ?

Yes, sorry mistype of engine type.

One thing that we've tried is the fuel pressure regulator valve, new one fitted which made the problem quieter for a short while (still there though).
1500mi or so later, it's back, same volume as before.

Next suggestion is to replace the fuel pump with a recon unit (probably not worth the £1k plus fitting for a new unit) but, will this fix the issue?
Open to suggestions from anyone that's seen this before.

Currently, it's the only thing that's wrong with the car apart from an occasional sticky gearshift ...

Finding another example of this car that hasn't (like mine) been to the moon and back is a current project because I like the car - a lot - and the engines appear mostly bomb-proof but until the the right car appears, I'd like to keep this one on the road and not sounding like a cement mixer in traffic :-D

Edited 1 November, 20251 Nov by gfkskoda
clarity

Check the plastic linkage for gear selector. It can get stiff and cause sticky gear changes. Had one snap on an old Seat as I had left it for about six months and it seized solid and wouldnt go into 4th/5th. I put a little grease on mine to free it up.

Alasdair

You could also try the trick with a length of hose. One end to your ear and move the other end around till the sound gets louder. It could help to track down the area the sounds coming from.

Alasdair

5 hours ago, Alasdair1 said:

Check the plastic linkage for gear selector. It can get stiff and cause sticky gear changes. Had one snap on an old Seat as I had left it for about six months and it seized solid and wouldnt go into 4th/5th. I put a little grease on mine to free it up.

Alasdair

Cheers, I'll take a look at that!

5 hours ago, Alasdair1 said:

You could also try the trick with a length of hose. One end to your ear and move the other end around till the sound gets louder. It could help to track down the area the sounds coming from.

Alasdair

I'll give it a whirl.
The good gents at Unit 18 were pretty categorical that it's fuel pump noise but as you probably know, it's basically a cam belt job to replace the fuel pump ... a recon unit is about £350, another £350 in labour, plus the other odd parts needed along with way, there's not going to be a lot of change from £1k total and the car has got just shy of 225k on the clock now, so I want to be 100% sure before I spend the money - it'll be the last big spend on this one I think.
If I can get it through another year (30k miles), great, but ...

Edited 2 November, 20252 Nov by gfkskoda