Sudden uncontrollable revs

[Livicol]

2019 vw transporter 2.0 tdi, suddenly, whilst in 3rd gear, it revved to the red line uncontrollably whilst coming off a roundabout. I quickly switched it off and waited a few minutes and it started and ran ok and got me the couple of minutes to home …carefully, it sounded and acted normal again.
162k on it with full history(ex AA) been running great, no smoke, noises etc. pulls well.
What do you think ? a pcv or turbo seal problem , oil/vapor ingestion?
Gutted, only had it a few months.

 

[Kind of Blue]

2019 vw transporter 2.0 tdi, suddenly, whilst in 3rd gear, it revved to the red line uncontrollably whilst coming off a roundabout. I quickly switched it off and waited a few minutes and it started and ran ok and got me the couple of minutes to home …carefully, it sounded and acted normal again.
162k on it with full history(ex AA) been running great, no smoke, noises etc. pulls well.
What do you think ? a pcv or turbo seal problem , oil/vapor ingestion?
Gutted, only had it a few months.

Welcome to the T6 Forum Livicol. DSG Gear Box or Manual? Do you imagine that it might have been out of gear a false neutral perhaps?

 

[Livicol]

Manual, part throttle in 3rd, I dipped the clutch and switched it off whilst coasting to the side of the road, all happened within 5 secs. Another few seconds and it would have went pop kind of high revs .
Thanks for replying.

 

[Kind of Blue]

Could the clutch have been slipping?

 

[Livicol]

no, I was barely on the accelerator

 

[whodat]

Sounds like a possible faulty accelerator pedal or wiring etc. (I'm not a mechanic though)
Can you get a Carista/OBD plugged in and do a Live Pedal test? You don't have to be driving to do it but can see if you can trigger the 100% when it shouldn't be.
Also - if you are lucky, it might have logged a fault somewhere.

 

[whodat]

That is so dodgy.
So you lost steering and brakes when you switched the engine off..... You were lucky it happened where it did. (if you can call that lucky)

Have you had any work done on it recently?

 

[JumpShip]

Check your oil level .

 

[Dundee_Kev]

Check your oil level .

Deffo check the oil level, if too high it can cause it to be sucked into the engine and run on the oil. Although, I would expect some smoke.

I think if it was a false reading from the throttle pedal, then when you hit the brake, it should kill the revs.

Runaway diesels are no fun, i wrote off a customers Saab diesel on road test a while ago. It started to drink it's own oil at 70mph on the outside lane of dual carriageway. As I was overtaking at the time and cars behind me I had no option but to continue past everyone and into the side of the road while controlling the speed with the brake and making a James bond smoke screen. One destroyed engine that the insurance wrote off, and one delighted customer that I did him a favour! I think that was my 5th runaway diesel and hopefully the last!

Hopefully its nothing serious and just a simple electrical glitch. It happens so quick, you don't have much time to think

 

[Dellmassive]

Check the oil.

Over filled?

Turbo leaking?

Might be work checking the intercooler to see if it wet with oil? (Should be dry)

 

[JumpShip]

Had just a couple go 'runaway' , quite scary

 

[Dellmassive]

It's much safer these days with modern diesel engines that have throttle bodies.

When I had an old Astra van with the Isuzu engine in it turbo go and had run away there was no throttle body to shut the air off... Tried stalling the engine but nothing would make it stop.

Surprisingly enough to me instead of a catastrophic explosion when it died it just stopped running.

 

[Livicol]

Sounds like a possible faulty accelerator pedal or wiring etc.
Can you get a Carista/OBD plugged in and do a Live Pedal test? You don't have to be driving to do it but can see if you can trigger the 100% when it shouldn't be.
Also - if you are lucky, it might have logged a fault somewhere.

Check the oil.

Over filled?

Turbo leaking?

Might be work checking the intercooler to see if it wet with oil? (Should be dry)

Oil level a couple of mm over max but sitting on slightly uneven ground. I was flip flopping off a roundabout at around 20mph, engine was just up to temp think.
I think intercooler is first port of call to see if there is oil. But still strange the turbo appears to be not worn, no smoke and performs well.
I have just been out to it this morning and it started fine and sounds ok, no cel light.....but I aint driving it until i further investigate!
My 3 month warranty has elapsed by a couple of weeks...sods law eh !
Thanks all, I will keep you posted.

 

[Sasquatch]

Diesel runaway (if thats what it was) doesn't have to have its origin at the turbo. It can equally pump through the breathers into the inlet tract.

For several reasons these motors are happiest with the oil halfway between the upper and lower dipstick markings, and no more, with very regular checks of the level. I wouldn't be happy with one of these even slightly above max.

 

[Dellmassive]

For a runaway you need un metered fuel.

It's normally engine oil.

You said it's only happened once, so possibly sucked oil from somewhere.

The DPF will catch any smoke from burnt oil. So you want see it at the tailpipe.

 

[Dundee_Kev]

The DPF will catch any smoke from burnt oil. So you want see it at the tailpipe.

On a proper runaway, dpf or no dpf, it will smoke.

If @Livicol you have it happen in the future, keep it in gear, do not press the clutch, control the speed with the brake (the brakes will over power the engine with ease) switch off the ignition, but only to auxiliary position as like @Dellmassive says, the modern diesels have proper throttle butterfly's which close and shut the air getting into the engine, this stopping or limiting combustion.

 

[Livicol]

Not got the time this morning, i am heading to work shortly. I got as far as getting the lower engine/sump cover off, nothing untoward visually especially around turbo, I haven’t got it up on ramps etc yet though access is limited.
Without removing bumper to get full access to intercooler what pipe work can I inspect for oil, any links for good clear diagrams?
I don’t understand, if it is ‘run on’ why it would happen so randomly?
Thanks for the reply’s.

 

[Sasquatch]

It won't be random, there will definitely be a cause - it's just we dont yet know what that may be

 

[The Bear78]

2019 vw transporter 2.0 tdi, suddenly, whilst in 3rd gear, it revved to the red line uncontrollably whilst coming off a roundabout. I quickly switched it off and waited a few minutes and it started and ran ok and got me the couple of minutes to home …carefully, it sounded and acted normal again.
162k on it with full history(ex AA) been running great, no smoke, noises etc. pulls well.
What do you think ? a pcv or turbo seal problem , oil/vapor ingestion?
Gutted, only had it a few months.

Random, off the wall idea incoming...

Did the engine continue to rev once you depressed the clutch or had you already turned it off?
Do you have cruise control buttons on the tip of the indicator stalk?

 

[Livicol]

On a proper runaway, dpf or no dpf, it will smoke.

If @Livicol you have it happen in the future, keep it in gear, do not press the clutch, control the speed with the brake (the brakes will over power the engine with ease) switch off the ignition, but only to auxiliary position as like @Dellmassive says, the modern diesels have proper throttle butterfly's which close and shut the air getting into the engine, this stopping or limi

Random, off the wall idea incoming...

Did the engine continue to rev once you depressed the clutch or had you already turned it off?
Do you have cruise control buttons on the tip of the indicator stalk?

No cruise, peasant spec, yes engine continued after clutch was pressed but it’ll happened within a sec or two getting ignition off. Someone else saying else where it’s not ’runaway’ as it would continued with ignition off.