Technical Embarrassing Q. Where is my...?

[Bonefish Blues]

...servo vacuum pipe located?

Images with pointy arrow welcomed!

Context is that I'm getting, on very specific occasions, some white smoke and I've been advised to check for dampness in the pipe. Specifically the overrun vacuum pulls a bit of brake fluid into the manifold and it burns up when you go back onto the gas pedal if brake master/servo seals are slightly leaky.

TIA, as always

 

[bugsymike]

Yours may look like this.
Bit unlikely , last servo that I worked on that did that was a Alfa Romeo Guilietta in 1969. Pulled the vacuum pipe off and dipped the servo , it was 3/4 full of brake fluid, stinking white smoke years before cars doing Regens

 

[Herts Hillhopper]

...servo vacuum pipe located?

Images with pointy arrow welcomed!

Context is that I'm getting, on very specific occasions, some white smoke and I've been advised to check for dampness in the pipe. Specifically the overrun vacuum pulls a bit of brake fluid into the manifold and it burns up when you go back onto the gas pedal if brake master/servo seals are slightly leaky.

TIA, as always

The servo itself is on the bulkhead at the back of the bonnet, behind the battery and with the brake fluid reservoir on top. The pipe is about 10mm diameter and heads off towards the engine. For a petrol I assume it still connects to the inlet manifold (been a long time since I had to look). On a diesel there’s an engine-driven vacuum pump on the end of the engine, to the left of the ECUs and battery.

In the image below (from my post about a stiff gearchange) the yellow pointy arrow points to what I believe to be the vacuum pipe to my servo. The small white ‘disc’ just above the arrow head is the ‘exit’ valve on the servo unit. It’s well buried! Note: I’ve removed the battery and disconnected the engine ECU here (as part of reaching the gear linkage)

 

[Herts Hillhopper]

Using this forum's newly updated ePER (the Fiat parts catalogue) shows the TwinAir also has a vacuum pump on the end of the engine - you can see it here: https://eper.fiatforum.com/en/Drawings/Detail/F/F/GIN/33/331/9/10/2/SubGroup - so that's where the servo pipe will connect to, and also shows there's therefore no way that brake fluid can get from there to being burned inside the engine... (that would only be possible if the servo was connected to the inlet manifold like on an older car)

 

[Bonefish Blues]

Thanks for taking the time to post that, appreciated.

I think I'm left with a DPF regen. then*. My OP on another forum was as below:

We have a 2013 Panda 4x4 diesel multijet, 112K, excellent full service history. It uses no oil, and fuel consumption is good.

It's used for school runs (10 miles e/w) and most short journeys. The school run is on A roads in the main and includes about 2-3 miles of dual carriageway driven at 70 mph. On some occasions (certainly not every time) and only one way down the dual when I've braked and gone round the roundabout at the end of the dual (Tingewick bypass on A421 heading towards Buckingham if anyone knows it) as I accelerate away I get plumes of white smoke for maybe 5 seconds - enough to make following cars drop back, anyway!

It's really peculiar. The rest of the time the car's perfectly well-behaved. The exhaust is clean and not sooty. Anyone any ideas at all? DPF not finished regen? Turbo problem? Injectors? The more I read the more I get confused!

*Unless you or ano know better?

 

[bugsymike]

Does sound to me like you need to either do a long higher speed journey to do a Regen or a Forced Regen using MES or similar.
What do others on Forum think?

 

[Herts Hillhopper]

I would say that is a DPF regen happening. Basically, when the car feels it needs to clear the particulate trap (based on a build up of back pressure in the exhaust), a small amount of diesel is injected into the exhaust strokes of the engine and ends up in the hot trap on the exhaust pipe, which raises the temperature in the trap and burns the particles away. Its this and the burned diesel being ejected from the exhaust that you are seeing as white smoke*.

If the car is regularly used for long fast runs, the high temperatures in the exhaust will keep the trap clear, but if its used lots around round town, it can become clogged and go into a forced regeneration of its own.

Generally this will happen if the revs are over 2000 rpm, the engine is fully warmed up and the car is travelling at a fairly constant speed. The fewer long journeys that are done, the less often this is able to happen, which means that when it does, more smoke is released... as you describe

Any modern diesel needs to have these long runs fairly often – a drive of at least 15-20 mins on a good fast road every few hundred miles -- and generally they are unsuited to only being used for town driving. If the trap becomes over-clogged, or a regen in progress doesn't complete, a yellow light comes on in the dash showing that the trap needs to be cleared (by going for a long drive). Very rarely, a software-forced regen might be needed, but really only if it never gets a long run at all.

To get a more complete picture of how a DPF cleans itself, and why these 'forced' cleans sometimes happen, see this now quite old article which describes the processes: https://www.whatcar.com/advice/owning/diesel-particulate-filters-everything-you-need-to-know/n1181)

( * not to be confused with clouds of black smoke, which is unburned diesel from a stuck EGR valve on an older diesel without a particulate trap)

 

[Herts Hillhopper]

By the way, it is the injection of this diesel into the exhaust stroke that leads to it ending up in the engine oil too... the 'oil change due' warning light is triggered by a certain number of regens having happened.

 

[Herts Hillhopper]

Another 'by the way'... some of the more recent small turbo petrol engines (such as that in my Skoda) also have particulate traps. A small turbo petrol can generate nearly as much particulate matter and NOX as a good 'clean' diesel, apparently (Source: https://www.whatcar.com/advice/buyi...articulate-filter-and-how-does-it-work/n19953 for example)

 

[Bonefish Blues]

I would say that is a DPF regen happening. Basically, when the car feels it needs to clear the particulate trap (based on a build up of back pressure in the exhaust), a small amount of diesel is injected into the exhaust strokes of the engine and ends up in the hot trap on the exhaust pipe, which raises the temperature in the trap and burns the particles away. Its this and the burned diesel being ejected from the exhaust that you are seeing as white smoke*.

If the car is regularly used for long fast runs, the high temperatures in the exhaust will keep the trap clear, but if its used lots around round town, it can become clogged and go into a forced regeneration of its own.

Generally this will happen if the revs are over 2000 rpm, the engine is fully warmed up and the car is travelling at a fairly constant speed. The fewer long journeys that are done, the less often this is able to happen, which means that when it does, more smoke is released... as you describe

Any modern diesel needs to have these long runs fairly often – a drive of at least 15-20 mins on a good fast road every few hundred miles -- and generally they are unsuited to only being used for town driving. If the trap becomes over-clogged, or a regen in progress doesn't complete, a yellow light comes on in the dash showing that the trap needs to be cleared (by going for a long drive). Very rarely, a software-forced regen might be needed, but really only if it never gets a long run at all.

To get a more complete picture of how a DPF cleans itself, and why these 'forced' cleans sometimes happen, see this now quite old article which describes the processes: https://www.whatcar.com/advice/owning/diesel-particulate-filters-everything-you-need-to-know/n1181)

( * not to be confused with clouds of black smoke, which is unburned diesel from a stuck EGR valve on an older diesel without a particulate trap)

Yes, I understand most of that. It's simply that I've not had to bother about it whilst running Euro 5 Volvo D5s - the other car is still an XC70. I don't know what kind of sophistry Volvo does with its DPFs, but they simply never clog, no matter what kind of cycle they are driven on. 1.3 multijets are not quite so forgiving, clearly! I do notice, however, a significant improvement since I've been school running more frequently than my wife. The engine is pulling so much more cleanly, no hesitation, faltering or suchlike.

 

[Bonefish Blues]

Still no smoke with me continuing as the main driver

 

[Bonefish Blues]

In fact, it's running beautifully (well, within the constraints of a 1.3 Multjet's loveliness quotient) I reflected this moring.

Motto seems to be that regular Italian Tunes are appreciated by the little car

So much so, it's having a nice new (to us) leather steering wheel tomorrow - it would have been earlier, but darned if I can get the airbag module off, even with all the Youtubes in China, as it were.

 

[Panda IIs]

In fact, it's running beautifully (well, within the constraints of a 1.3 Multjet's loveliness quotient) I reflected this moring.

Motto seems to be that regular Italian Tunes are appreciated by the little car

So much so, it's having a nice new (to us) leather steering wheel tomorrow - it would have been earlier, but darned if I can get the airbag module off, even with all the Youtubes in China, as it were.

I have a couple of photos to show where the airbag clips hide (4x4 TA) if that helps? Clips are pretty stiff and plain metal rod or allen key is better than any flatbladed screw driver (which tends to slip off spring) but agree its a real pain first time!

 

[Bonefish Blues]

I have a couple of photos to show where the airbag clips hide (4x4 TA) if that helps? Clips are pretty stiff and plain metal rod or allen key is better than any flatbladed screw driver (which tends to slip off spring) but agree its a real pain first time!

The Man did it yesterday and very nice it looks too

 

[Bonefish Blues]

Looks well with the grey airbag cover, I think (our silver car comes with grey trim)

 

[Herts Hillhopper]

Yes, I understand most of that. It's simply that I've not had to bother about it whilst running Euro 5 Volvo D5s - the other car is still an XC70. I don't know what kind of sophistry Volvo does with its DPFs, but they simply never clog, no matter what kind of cycle they are driven on. 1.3 multijets are not quite so forgiving, clearly! I do notice, however, a significant improvement since I've been school running more frequently than my wife. The engine is pulling so much more cleanly, no hesitation, faltering or suchlike.

I guess it’s just running hotter, which should keep things ‘cleaner’ longer.

So yes, the Italian Tune Up really will make a difference.

The leather wheel is nice. All 3 of my post 2012 4x4s have had them. I noted (more recently) that the door cards of the rear doors on tbe most recent are just black plastic. The previous two had ‘fake leather’ (or PVC ) infills like the front doors have. And we know the rear speakers were dropped by 2018 or so.

 

[varesecrazy]

Using this forum's newly updated ePER (the Fiat parts catalogue) shows the TwinAir also has a vacuum pump on the end of the engine - you can see it here: https://eper.fiatforum.com/en/Drawings/Detail/F/F/GIN/33/331/9/10/2/SubGroup - so that's where the servo pipe will connect to, and also shows there's therefore no way that brake fluid can get from there to being burned inside the engine... (that would only be possible if the servo was connected to the inlet manifold like on an older car)

@lunchbeers is Staring around here as we speak..

Anybody delved further..?

 

[lunchbeers]

@lunchbeers is Staring around here as we speak..

Anybody delved further..?

You rang?

Whilst I wasn't concentrating on the vacuum pump, there is definitely a couple of hard pipes which have push fit connectors on there... the one I removed (for access) showed no trace of any fluid, nor would I expect any as noted above.