What happened during this stressful episode?

[Samro]

After towing a 2 ton caravan 1800m up a mountain to a scenic campsite in the French alps, we left only to get a puncture in a caravan tyre!
I quickly looked for somewhere flat to change the caravan when and I had to briefly perform a hill start on a mega incline!
This is a T6.1 with a DSG box and the clutch got bloody hot and stank and a "Low Brake Fluid" warning popped up and van would not pull away. This led to having to reverse a large twin axle caravan an alarmingly long distance to find flat enough ground to change the flat tyre!
Brake fluid checked and all ok and we pushed on to lake Garda without issue.
Ever since the episode of the van refusing to climb the hill, I've had a load of faults which I've cleared down with Carista.
The faults varied and all seemed totally unrelated to the experience on the mountain.
I'll monitor to see if any faults reoccur, but the whole thing has been a little odd!

 

[rolla]

I'm interested in how you determine that the clutch was smelling..?
As it is fully encapsulated inside a hermetic cover(100% wet clutch) and the only smell would be from the gearbox breather, which vents into the engine bay...
If you can smell the clutch through that, well it's definitely time for a check up, vag-com the dsg drivetrain system, looks at oil temp and any other parameters that are held, like overtemps in the box, clutch pressure, activation pressures etc.... far too many parameters to even care to remember..
I am not near my van, but when I put the 4mo dsg drivetrain into it, first thing I did was scan just the gearbox,
I didn't even have the propshafts, rear diff or anything connected except the 17pin plug,
I just wanted to check the operation and reading of vag-com on the T6 gearbox into my T5.1 ecu and that it didn't throw any codes.

Fact that you could smell the (assumption now) .. transmission fluid with a burning smell is not the best news.
Sorry to be the harbinger of doom but for longevity of your bus it is a must.

 

[Samro]

I'm interested in how you determine that the clutch was smelling..?
As it is fully encapsulated inside a hermetic cover(100% wet clutch) and the only smell would be from the gearbox breather, which vents into the engine bay...
If you can smell the clutch through that, well it's definitely time for a check up, vag-com the dsg drivetrain system, looks at oil temp and any other parameters that are held, like overtemps in the box, clutch pressure, activation pressures etc.... far too many parameters to even care to remember..
I am not near my van, but when I put the 4mo dsg drivetrain into it, first thing I did was scan just the gearbox,
I didn't even have the propshafts, rear diff or anything connected except the 17pin plug,
I just wanted to check the operation and reading of vag-com on the T6 gearbox into my T5.1 ecu and that it didn't throw any codes.

Fact that you could smell the (assumption now) .. transmission fluid with a burning smell is not the best news.
Sorry to be the harbinger of doom but for longevity of your bus it is a must.

Exactly my point on the smell front. The stench was the same as you'd expect from overheated brakes.
With a DSG box what could this stench be from?
The vehicle could not cope with me attempting a hill start on such a steep gradient with a big caravan on the back. The fault that came up related to brake fluid level! Fluid levels have been checked and are fine.
Van has been driving fine since the issue other than random faults that came up including air bag and can bus issues, but now the faults
Are cleared down the air bag light remains off and all seems fine.
Certainly the vehicle drives fine.
What could the burning stench be on a van with a DSG box (not 4mo), given that this occurred attempting a hill start with a large caravan on back?

 

[rolla]

Exactly my point on the smell front. The stench was the same as you'd expect from overheated brakes.
With a DSG box what could this stench be from?
The vehicle could not cope with me attempting a hill start on such a steep gradient with a big caravan on the back. The fault that came up related to brake fluid level! Fluid levels have been checked and are fine.
Van has been driving fine since the issue other than random faults that came up including air bag and can bus issues, but now the faults
Are cleared down the air bag light remains off and all seems fine.
Certainly the vehicle drives fine.
What could the burning stench be on a van with a DSG box (not 4mo), given that this occurred attempting a hill start with a large caravan on back?

Well they have hill start assist, stop you rolling back, so pulling from a dead stop would be a massive effort if you have a 2ton weight behind, did you rev the granny out of it ..?
It could well be that you boiled the dsg oil and the smell is from that, reason I said I don't have my van close is I cannot read what error codes the dsg would store, the parameters are longer than War & Peace book, just for the gearbox,
I doubt ODIS has this level of report, it may... may not, Vag-Com is such an excellent tool if you need to look deeper.
You have to go into the coding section, log in and read all the sectors it covers ... it's immense.
Here is something I just found on my desktop, to show you what I mean, this is from when I was trying to bleed my haldex (shit seperated the oil and it wouldn't bleed fresh oil into haldex, even after pressure bleeding, I washed it through with brake cleaner and sucked all that with crap out, it bled straight away then) .. but see below I selected these for my pain... couple of years back now...


Address 22: AWD (0AY 907 554 L)

15:03:16
IDE00019 Voltage terminal 30 14.2 V
IDE00920 Front left wheel speed 18.3 km/h
IDE00921 Wheel speed: right front 22.4 km/h
IDE00922 Left rear wheel speed 21.7 km/h
IDE00923 Right rear wheel speed 21.4 km/h
IDE01617 Clutch temperature 19.70 C
IDE04502-MAS04730 Haldex clutch: status-Degree of blockage 0.00 %
IDE05707 Haldex clutch pump: current 0.005 A
IDE05708 Haldex clutch pump: PWM signal 0 %
IDE05710 Haldex clutch pump: voltage 0.0 V

The bold type is just a couple of strings used to check it, most likely a factory operational check for DSG'g

I would say the b/fluid light came on as when you released the brakes it all surged away from the sensor, as you said level warning right ..?
Get the box serviced, get the parameters checked elsewhere before it goes to VW, just incase these errors get cleared ... sorry bud I can't think of anything else atm... good luck .. dsg boxes are fairly reslient.

 

[DaveD]

The fault that came up related to brake fluid level!

The T6 doesn't have a separate clutch fluid reservoir, it uses the brake fluid.

 

[Podge]

Maybe a caliper got hot and the fluid overheated. That would account for the clutch/brake smell. It might not have wanted to pull away if a wheel was locked. No more mountains or towing and it now seems ok. I've just come back from a France/Spain/Portugal 4300 mile trip towing over big mountains so I now how hard everything has to work! Sometimes seizing calipers don't show up when cold. If you take it to your local friendly MOT test place you could ask them to do a brake test directly after some serious brake pedal abuse.

 

[Samro]

I knew I was asking a lot of of the van to pull away at a standstill under those conditions and did not persist in giving revs. Two attempts was enough for me to give up. I am sure that I recall that the engine would not pick up revs when attempting to pull away. It was all a bit of a nightmare due to the (sh** scarey) drop at the side of the road, steep incline, crying wife, etc, so can't really be 100% on this, but I think the van stalled on both attempts of trying to pull away and I decided to reverse down the road to a position where there was a flattish area to change the wheel.
Utter nightmare! Maybe I'll book in with @BognorMotors tk check things over when I get back. Certainly will need an oil change and maybe now a premature transmission oil change for peace of mind.

 

[Samro]

The T6 doesn't have a separate clutch fluid reservoir, it uses the brake fluid.

Not for DSG boxes.

 

[jayc001]

Pretty sure I've triggered a warning of transmission overheating when towing my caravan on my old t5.1. It has the same dq500 as t6/6.1 so assume same warning will apply.

If would come on when doing low speed manoeuvres especially after being in traffic or excessive ambient (30+) temperature.

You mention it stalled on pull away? Generally the dsg will get a bit snatchy if fluid is low especially when hot. Perhaps you have a leak which is getting on something hot and giving the smell?