Anyone else got this funny noise?

[TEESIXY]

I think its done it from new, but its a noise which only seems to happen on long journeys, after around 20 miles or so.
It starts, most noticeably in top gear as it gets to about 1800 rpm (its gone after 2000), a sort of buzzing noise, almost like a bracket or plate is vibrating. I'm convinced its something to do with the turbo, as any movement of the accelerator instantly varies the noise.
A waste of time going to the dealer with this, unless its a common thing. Anyone else got it?

Oh, its a 150ps

 

[Loz]

I found some of the heat shielding under the van was out of place and rattling, it was hanging down just a little and was was getting caught in the air traveling underneath. I bent it back wher it should be.

 

[mmi]

I think its done it from new, but its a noise which only seems to happen on long journeys, after around 20 miles or so.
It starts, most noticeably in top gear as it gets to about 1800 rpm (its gone after 2000), a sort of buzzing noise, almost like a bracket or plate is vibrating. I'm convinced its something to do with the turbo, as any movement of the accelerator instantly varies the noise.
A waste of time going to the dealer with this, unless its a common thing. Anyone else got it?

Oh, its a 150ps

Probably yes. Engine hot. Gears 5-7 (DSG), light foot on accelerator, rpm 1400-1800 rpm. Goes away when foot off from accelerator, or full throttle. Pretty random, comes and goes but when happens stays on for several minutes, so had to visit service more than once to be able to demonstrate this. Definitely not DPF regen - ruled out by VCDS. Hopefully same root cause as in my sound clips in thread Tick over noise . I'll report back as soon as I have verified if near future actions of VW will change things.

 

[Mooncat]

If you have VCDS look at what the engine is doing. That sounds like optimum conditions for the EGR to be near to, if not fully, open. I need to look at what gets monitored in VCDS, but if you think it is turbo related, see what is happening to the vane pack.

Not something I've noticed on the T6 4Motion but our Yeti 4x4 has some nasty gear lash noise at low rpm which sounds very different to heat shield noise which I had to sort on that too!

 

[mmi]

If you have VCDS look at what the engine is doing. That sounds like optimum conditions for the EGR to be near to, if not fully, open. I need to look at what gets monitored in VCDS, but if you think it is turbo related, see what is happening to the vane pack.

Not something I've noticed on the T6 4Motion but our Yeti 4x4 has some nasty gear lash noise at low rpm which sounds very different to heat shield noise which I had to sort on that too!

Thanks. I also need to have another look at EGR - have already done some and seems to work ok, or at least logically- EGR values align with lambda values. But really can't tell more than that the EGR is not stuck .

Just curious - have you ruled out the flywheel as lash noise source in your Yeti?

 

[Mooncat]

Hmmm DMF! The Yeti makes the noise if you let the revs drop too much but have the drive train loaded. Never even thought about the flywheel, I just drop it down a cog so it's not labouring and everything is ok but I will pay a bit more attention to it.

 

[TEESIXY]

This noise is still there. The dealer let a tech come out with me and he heard it too. They are talking about having the van for a couple of days to try and sort it, but i'm not confident they will because it is only really bad when the van's on a good run.
However, iv'e narrowed it down a bit- its related to the heater. It doesn't do it until the heater is hot. On cruise at 70, its making the noise all the time, a sort of buzzing, but if i turn the temp control to cold, the noise nearly fades away after a few seconds. When i turn the heat back up, the noise is back after a few seconds. The fan on or off makes no difference, and if i press the air outlets by my feet to one side, the noise seems to change.
If you've read this far any idea's would be appreciated !
The dealer is a 50 mile trip, so its not easy to keep taking it back if they dont sort it.

 

[TEESIXY]

UPDATE-
I've solved it, two days before the dealer was going to have a go. Under the bonnet, on the bulkhead, the N75 moo valve has a cone shaped filter attached to it, and, although apparently correctly located was touching metalwork behind it causing an extremely annoying buzzy rattle.
Why the heater temp switch affected it, i've no idea. But its sorted !

 

[Davejo]

UPDATE-
I've solved it, two days before the dealer was going to have a go. Under the bonnet, on the bulkhead, the N75 moo valve has a cone shaped filter attached to it, and, although apparently correctly located was touching metalwork behind it causing an extremely annoying buzzy rattle.
Why the heater temp switch affected it, i've no idea. But its sorted !

What does the N75 moo valve do?...

 

[TEESIXY]

I think it operates a solenoid,controlling the turbo variable vanes, which control boost, its known as a moo valve because that's the noise it makes when its playing up.

 

[TEESIXY]

UPDATE-
I've solved it, two days before the dealer was going to have a go. Under the bonnet, on the bulkhead, the N75 moo valve has a cone shaped filter attached to it, and, although apparently correctly located was touching metalwork behind it causing an extremely annoying buzzy rattle.
Why the heater temp switch affected it, i've no idea. But its sorted !

Well, another update! It wasn't the above after all (this noise only starts after a few miles have been covered from cold) The good news is that after weeks of trying different things i have found that if i wedge between the heater feed and return pipes at the bulkhead,under the bonnet with a piece of cloth, the noise is gone. Take it out and its back.
So its something to do with the heater. I was a bit tempted to leave it like that, but the vans going in for a new plate and rubbers which support the charge cooler on top of the engine ( that was their diagnosis), so i will give them the new info and see if they can find the cause of the noise.

 

[mmi]

Probably yes. Engine hot. Gears 5-7 (DSG), light foot on accelerator, rpm 1400-1800 rpm. Goes away when foot off from accelerator, or full throttle. Pretty random, comes and goes but when happens stays on for several minutes, so had to visit service more than once to be able to demonstrate this. Definitely not DPF regen - ruled out by VCDS. Hopefully same root cause as in my sound clips in thread "Tick over noise". 150ps. I'll report back as soon as I have verified if near future actions of VW will change things.

May be it's time to update mine, too.

After the post above even all the injectors were replaced but it didn't make any difference. Then again, just a few weeks ago the van went in for repair of oil leak around crankshaft front end. While doing that they found that the timing belt and the tensioner were "not of the best possible quality" so they replaced also those. Actually there is a service note about those but with other "symptom" - old fashioned generator belt rhytmic "rubbing" noise on idle- so that was earlier not considered to be related to my noise.

After the repair to my surprise the strange noise was gone. As I had visited the service point regularly complaining about the noise more than a year, I was confident that, in addition to oil leak, they had also repaired something else and were just testing me if I notice any difference to see if I'm just complaining for nothing. After a week I gave up and called and asked if they were really honest what they did last time. They still claimed that nothing else was done. So can I really trust them, they were supposed to fix only the oil leak, but they also took away that irritating noise? Now have driven a few thousand km's