Blue smoke on cold start: 1.9 PD-TDI

Hello,

The Ibizafrom forum has a link to an interesting video about hardware damage or wear.
http://www.youtube.com/watch?v=Ul8M9u6w3JM&feature=player_embedded
(This is a BPX model, which originally had 160 horsepower, with a claimed mileage of 56,000 km and a new turbocharger installed at 53,000 km.)

If "blue" refers to unburned oil, then it can only be added to the exhaust side, meaning through the blower shaft, in my opinion.
The extra blue smoke when accelerating in the city probably also points in that direction.
Or am I wrong with these assumptions?

The link to the topic:
http://www.ibiza-forum.de/board21-seat-ibiza-6l-und-seat-cordoba-6l/board6-m%C3%A4ngelliste/85862-ibiza-cupra-tdi-springt-komisch-an/

2 Monate Standzeit ist nicht gut. Sommerdiesel noch im Tank ist hoffentlich ausgeschlossen. Was sagt die LLruheregelung? Glühfunktion prüfen. DSwitch to iFi.
The mileage is very low for a 2004 vehicle! However, I would still recommend replacing the timing belt/adjusting the timing.

ulf wrote:

... If "blue" refers to unburned oil, then it can only be added to the exhaust side, meaning through the blower shaft, in my opinion.

Why unburned?
Oil burns blue at relatively low temperatures, such as with diesel.
At higher temperatures, it will eventually turn black.


But it's not necessarily oil either... Because even low-quality diesel can cause that. However, since the original poster has already refueled and the smoke persists, it definitely doesn't come from the diesel.

What are the options?
Turbocharger (whether on the intake or exhaust side... but with a new turbo like that, it's more likely to be questionable).
Shaft seals (I haven't heard much about these in modern cars).
Oil separator (it seals tightly and pushes the oil back into the intake manifold... especially after the engine has been idle).
Leaking tandem pump (potentially leaks oil into the fuel... but this is probably more of a theoretical possibility).
Leaking PD elements (the seals in the head are prime suspects).
Please provide the text you would like me to translate from German to English.

Bertil wrote:

Why unburned? Oil burns at relatively low temperatures (like with diesel) and produces a blue flame.

I thought that oil, with the typical excess air in a diesel engine at idle, burns similarly "colorless" to the diesel itself...

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What is possible:
Turbocharger (whether on the intake or exhaust side... but with a new turbo, it's more questionable) Unless, of course, the car has been poorly tuned, and the new turbocharger has already been mechanically aged by several hundred thousand kilometers.
Or, perhaps a supposedly "like new" IhBäh bargain loader was installed

Quote:

.

Shaft seals (I haven't heard much about them in modern cars).
Oil separator (it seals tightly and pushes the oil back into the intake manifold... especially after the engine has been idle).
Leaking tandem pump (potentially leaks oil into the fuel... but this is probably more of a theoretical possibility).
Leaking PD elements (the seals in the cylinder head are prime suspects) What I noticed, after the initial smoking phase, were the further blue clouds whenever some gas was given: as if, for example, some oil was still clinging to the turbine wheel, which is then thrown into the exhaust stream as the exhaust gas flow and turbocharger speed increase... }

ulf wrote:

... I thought that Möl would burn in a similar "colorless" way as the diesel itself, due to the typical excess of air in a diesel engine at idle... ?

Not when the engine is cold.
You need a much higher temperature for that.
And where is that supposed to come from, right after a cold start?
Blue smoke during a cold start can only be caused by incomplete combustion in the combustion chamber. Everything else is far too cold after a cold start to vaporize or burn oil.


Okay, Ulf... Let's talk about your younger days -> BMW 02 series -> No turbo -> What were these cars known for? -> Right, the blue smoke coming from the exhaust.
The reason for the blue smoke coming from the exhaust was a vacuum in the crankcase, which was drawing oil vapor into the intake manifold. This caused the engine to smoke excessively.
And this is especially true when the engine is warm.

Once, my Jetta had a leaky valve stem seal on the intake side. What kind of blue smoke do you think it produced?

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...Unless, of course, the vehicle had been poorly maintained and the new engine already had several hundred thousand kilometers of mechanical wear. Or, perhaps a supposedly "like new" IhBäh bargain loader was installed .

Ja .... I agree.

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What I noticed (after the actual end of the pre-start smoke) were the further blue clouds, as soon as any gas was given: as if, for example, some oil was still clinging to the turbine wheel, which is then thrown into the exhaust stream as the exhaust flow and turbocharger speed increase...

Or, the temperature finally becomes high enough to allow the oil to burn relatively cleanly .

In my opinion, the blue smoke is coming from the combustion chamber.


EDIT:
A two-stroke mixture smokes (depending on the oil used), but it also smokes blue... doesn't it? Why is that?

Bertil wrote:

ulf wrote: ... I thought that Möl would burn "colorless" in the typical air excess of a diesel engine at idle, similar to the diesel fuel itself...? Not when the engine is cold. You need a much higher temperature for that. And where is this supposed to come from immediately after a cold start?

Could the combustion of the diesel fuel be sufficient for this? Oil from the compressor side of the turbocharger would be drawn in as a mist and would essentially enter the cylinder as a refined mixture, similar to a gasoline engine. . .

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The blue smoke during cold start can only come from incomplete combustion in the combustion chamber. Everything else is far too cold after the cold start to vaporize or burn oil.

What about the turbine wheel? Large surface area, low mass -> it should very quickly reach the temperature of the passing exhaust gases. If the exhaust gases, after passing through the cold manifold and turbine housing (the soot layer on the internal parts is likely to act as an insulator and reduce the cooling of the exhaust gases on their way to the turbine), are warm enough at the turbine wheel to vaporize any oil clinging to it, we would have an explanation for the blue smoke coming from the exhaust. Let's drop a drop of oil from the dipstick onto a warm exhaust manifold...

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BMW 02 series -> No turbo -> What were these cars known for? -> Correct, the blue smoke coming from the exhaust. The reason for this blue smoke... cloud was a vacuum in the crankcase, which drew oil mist into the intake manifold. As a result, the engine smoked like crazy.

If I recall correctly, the key word was "valve stem seals," as in your case (why would there be a vacuum in the crankcase in that situation? ):

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. In my Jetta, there was once a leaky valve stem seal on the intake side. What kind of blue smoke cloud did it produce...?

I believe that immediately. But that doesn't exclude the possibility for me that blue smoke can also originate in the exhaust area.

Let's examine the inlet temperatures of the oil being drawn in through damaged valve stem seals.
1. Intake side -> continuously cooled by the incoming airflow -> probably not sufficient to vaporize oil.
2. Combustion chamber -> water-cooled; oil may potentially vaporize at the bottom of the piston or near the AV (Antivalve).
3. Exhaust tract -> hottest, as it only sees exhaust gases.

"If the early BMWs had carburetor engines, they always drew in a flammable gasoline mixture even during periods of acceleration (the classic scenario: a BMW brakes to a stop on the highway in traffic and emits blue smoke; as soon as it accelerates again, the smoking stops). This means that there probably wasn't enough air available for a verschandeln combustion of the additionally drawn-in oil, but the combustion heat of the idle mixture could cause the oil to vaporize due to the lack of air, resulting in blue smoke (almost) without oil burning."
Regarding fuel injectors, I find it highly questionable whether the oil drawn in during the shut-off phase could form a spark-ignitable mixture with the fresh air. If not, the oil mist circulating within the engine would reach the hot surfaces of the exhaust system and vaporize there, which, in my opinion, is where the blue smoke originates.

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Quote: What I noticed, after the initial smoke from the start-up, were the further blue clouds that appeared as soon as any gas was given: as if, for example, some oil was still clinging to the turbine wheel, which is then thrown into the exhaust stream as the exhaust flow and turbocharger speed increase... Or perhaps the temperature is finally high enough to allow the oil to burn relatively cleanly

. Which parts could suddenly cool down so much during the short bursts of acceleration at the end of the video that the oil starts to burn with smoke again?

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The blue smoke I'm seeing, in my opinion, is coming from the combustion chamber... . . EDIT: A mixture of two-stroke engine fuel also produces blue smoke (depending on the oil used), doesn't it?

OK, oil is being burned. But without excess air, or with a mixture that is tending towards being rich, meaning it's completely different from a diesel engine in terms of lambda at idle?
This, in my opinion, does not exclude the possibility that blue smoke can originate from only vaporized oil in the exhaust system, as mentioned above .

It looks more like "leaking oil," either from the loader into the intake manifold (and from there, everything gets oily) or worn valve guides/seals.

As with "new" chargers in reality, it's debatable. Please keep in mind those clever people who make "Ching-Chong" knock-off chargers, or so-called "reconditioned" chargers.

I would start by checking the intake manifold to see if there's excessive oil in it. If there is, verschandeln it and get a brand new turbocharger. If not, perform a compression test and possibly remove the cylinder head.

You really shouldn't drive that old car for very long.

Best regards, Rainer.

dieselschrauber wrote:

You really shouldn't drive it much longer with this old car.

. . . with 56,000 km on the odometer and a new charger - supposedly .
Was ist hier wohl los? / Was ist hier los? / Is something wrong here? / Has someone been taken advantage of?

He should go to a Seat dealership and ask them to provide him with the vehicle's history.

ulf wrote:

Could the combustion of diesel fuel be sufficient? Oil from the compressor side of the turbocharger would already be drawn in as a mist, and would therefore essentially enter the cylinder as a refined mixture, similar to a gasoline engine. . .

This, however (as I already mentioned), passes through the combustion chamber. But you said "on the exhaust side," and that certainly cannot be the case during a cold start...

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How about the turbine wheel? Large surface area, low mass -> that should, in my opinion, very quickly reach the temperature of the passing exhaust gases.

However, it will warm up too slowly to allow the oil to burn.

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Let me drip a drop of oil from the dipstick onto a warm exhaust manifold...

If I do it 5 seconds after a cold start (and then turn the engine off again), absolutely nothing happens. And that's exactly what's happening here.

Quote:

Quote: BMW 02 series -> No turbo -> What were these cars known for? -> Correct, the blue smoke coming from the exhaust. The reason for this blue smoke... from the clouds was a vacuum in the crankcase, which drew oil mist into the intake manifold. As a result, the engine smoked like crazy. If I recall correctly, the key word was "valve stem seals," as with you (but why would there be a vacuum in the crankcase in that case?).

Sorry... Overpressure in the lower ground (KG) and underpressure in the intake manifold... I misspelled that... I guess it was too late.

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Let's examine the inlet temperatures of the oil being drawn in through damaged valve stem seals.
1. Intake side -> continuously cooled by the incoming airflow -> probably not sufficient to vaporize oil.

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And where does the oil sludge often come from on the intake valves? That will only happen if the temperatures are high enough. But you're right, this is probably where the least amount will burn.

2. Combustion chamber -> water-cooled; oil may potentially vaporize at the bottom of the piston or near the AV (Antivalve).

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And what about the combustion process itself? Do you not have those where you are?

3. Exhaust tract -> hottest, as it only sees exhaust gases.

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Okay, regarding the exhaust system, I see two aspects: the combustion chamber side and the external side. I suspect little (or nothing) happens on the external side, at least immediately after a cold start. Quote: ;)Or perhaps the temperature is finally high enough to allow the oil to burn relatively cleanly

Which parts could suddenly cool down so much during the short bursts of acceleration at the end of the video that the oil starts to smoke again?

My statement did not refer to the video.

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Okay, so it seems like oil is being burned. But without excess air, or with a mixture that's tending towards being rich, meaning at least in terms of the lambda value, it's completely different from how a diesel engine operates at idle?

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No! There is also enough air for combustion in gasoline engines, and there is still plenty of it. ;)In my opinion, this does not exclude the possibility that blue smoke can be generated from only vaporized oil in the exhaust system, as mentioned above

}.
Yes!
Where do you get the necessary temperature for that in the first few seconds?
It definitely struggles in the first 10-15 seconds. However, because the engine immediately starts smoking, I see the problem exactly as Rainer described. The oil is burning in the combustion chamber. How it gets there is a separate issue.

I suspect that the loader arm might not be "completely sealed."
It's quite possible that it's leaking oil on both the intake and exhaust sides. This would explain why it smokes immediately upon starting (intake side) and why it tends to produce more bluish smoke when accelerating (exhaust side), suggesting that not as much oil is being drawn in or burned in the combustion chamber.
Best regards,

Bertil wrote:

ulf wrote: Could the combustion of diesel be sufficient? Oil from the compressor side of the turbocharger would already be drawn in as a mist, and would therefore enter the cylinder as a refined mixture, similar to a gasoline engine. . This, however (as I already mentioned), passes through the combustion chamber. But you said "on the exhaust side," and that certainly cannot be the case during a cold start...

Okay, so let's also consider oil sources on the fresh air side, but:

Quote:

Quote: 2. Combustion chamber -> water-cooled, possibly causing oil to vaporize at the bottom of the piston or near the intake valve And what about the combustion process itself? Gibt es die bei dir nicht?

Doch, aber bisher denke ich, dass Ölnebel in der Diesel-Verbrennung mit reichlich Luftüberschuß (direkt nach dem Kaltstart ist die AGR noch nicht aktiv) nicht so dichten Blauqualm erzeugen würde wie in dem Video, wo der Motor schon längst rund läuft, incl. Laufzsince it was initiated by the AgA.
The thick, smoky haze in the video seems more like vaporized (i.e., unburned) oil, and for that to happen, the oil would need to enter the exhaust stream after combustion... ?

Quote:

Quote: 1. Intake side -> continuously cooled by the fresh air flow -> probably not sufficient to evaporate oil. And where does the oil sludge often come from on the intake valves? That only works if the temperatures are high enough. But, you're right, this is probably where the least amount will burn.

With continuous wide-open throttle (WOT), the exhaust valves (EV) will probably get hot enough to vaporize oil, but certainly not immediately after a cold start of a diesel engine like in the video.

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Quote: Which parts should suddenly cool down so much during the short gas bursts at the end of the video that the oil starts to burn and smoke again? My statement did not refer to the video.

However, I think we should orient ourselves based on that.
However, I am surprised by the description from the Ibiza driver, stating that no smoke is visible with a warm engine. According to this, there must be at least one oil leak source involved, which is only active for a short time after a cold start, but later permanently seals itself as the engine approaches normal operating temperatures .

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Since the engine immediately smokes, I see the problem exactly as Rainer wrote.

The oil is burning in the combustion chamber. See above: With such residue despite excess air? If it's burning, then the smoke indicates incomplete combustion?
Why should a burning oil spill, despite having plenty of excess air, suddenly stop burning?
If there were more oil than air (and therefore not all the oil could be burned), then, in my opinion, the combustion of all the oxygen would release so much energy that the unloaded engine would spin up rapidly, similar to a free-wheeling mechanism caused by a broken impeller shaft }.

ulf wrote:

The thick, smoky haze in the video seems more like just vaporized (i.e., unburned) oil, and for that to happen, the oil would need to enter the process after combustion, i.e., on the exhaust side...

Here's a little tip for you to think about...
The MSG has no idea about the extra "fuel" (the oil). Therefore, the engine is running extremely rich. There's no more talk of "excess air".... So, it's smoking .

Bertil wrote:

A small tip for reflection... The MSG (presumably a diagnostic system) has no idea about the additional "fuel" (the oil). Therefore, the engine is running extremely rich. There's no more talk of "excess air". So, it's smoking

. When the oil burns in addition to the fuel, additional energy is released, which should cause an unloaded diesel engine to rev up (otherwise, a TDI wouldn't be able to continue running after a turbocharger shaft failure and ignition shut-off, by drawing in oil mist from the turbocharger lubrication system and burning it).
The "idle speed control" software component of the MSG (that's its purpose) detects this tendency towards high RPM and will reduce the EM (electromagnetic field) accordingly, ensuring that the idle speed remains constant within the defined control parameters .

Therefore, it is likely that when burning Möl instead of a portion of the normal exhaust gas in the idle of a diesel engine (without EGR), no significant air shortage will occur... ?
Unless Möl requires significantly more air for complete combustion than diesel (mass ratio ~ 14.5), and/or Möl has a significantly lower calorific value than diesel.

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The MSG has no idea about the extra "fuel" (the oil). Therefore, the engine is running extremely rich. There's no more talk of "excess air".... So, it's smoking icon_wink.gif

"There's definitely an excess of air during a cold start, but it's not the primary cause of the smoke. A global lambda value of 5-7 doesn't necessarily mean 'clean' operation."
To achieve a LOCAL lambda value ranging from 1.6 to 0.8 (flammable), you first need heat to cause the diesel to "evaporate." Only then do "lambda = infinity" layers form around the diesel droplets. These layers then burn down to lambda = 0.

The "pure air" theory doesn't apply here. The engine either has insufficient heat (glow plugs) and/or too much fuel. Oil in the intake manifold would be a good starting point. Once the engine stops cooling the compressed air too much, it can burn that small amount of oil cleanly.

If the oil is leaking past the exhaust valves, it wouldn't produce any smoke initially. It would only start smoking after a few seconds, when something somewhere reaches a temperature above 100°C.

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As with "new" chargers in reality, it's debatable. Please keep in mind those "Ching-Chong" knock-off chargers or so-called "rebuilt" chargers. icon_rolleyes.gif

The boost pressure log in the linked thread doesn't show any chip tuning. However, it does show a turbocharger that's being controlled in an interesting way. At 1500 rpm - 4500 rpm with the throttle fully open in 3rd and 4th gear, the log shows a good +280 mbar at 2500 rpm. That's not a great performance for a new turbocharger... It's quite possible that what's being used here is a quote from RK: "cheap, imitation turbochargers."

The question arises as to why someone would replace it after 53,000 km, and then still experience problems that point to an issue with the turbocharger?


Hello FabiaCombiTDI.

FabiaCombiTDI wrote:

"There's definitely an excess of air during a cold start, but it's not the primary cause of the smoke. A global lambda value of 5-7 doesn't necessarily mean 'clean' operation."

You're right... That's exactly what I meant.

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If the oil is leaking past the exhaust valves, it wouldn't produce any smoke initially. It would only start smoking after a few seconds, when something somewhere reaches a temperature above 100°C.

That's right!
You'll need at least 5-10 seconds, and possibly even longer, for the exhaust system to reach 100°C.



@Ulf

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If the oil burns in addition to the fuel, additional energy is released, which would cause an unloaded diesel engine to rev up (otherwise, a TDI wouldn't be able to continue running after a turbocharger shaft failure and ignition shut-off by drawing in and burning oil mist from the turbocharger lubrication system).

The amount of available resources is far too small.
On the contrary. In this amount, oil actually inhibits combustion.

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The software component "idle speed control" of the MSG (that's its purpose) detects this tendency towards high RPM and will reduce the engine output (EM) so that the idle speed is kept constant within the defined control parameters

.
The regulation doesn't recognize that at the initial startup moment... We've already discussed .

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Therefore, it is my opinion that when burning Möl instead of a portion of the normal exhaust gas in the idle of a diesel engine (without EGR), no significant air shortage should occur...

Der Kaltstart ist immer ganz hart an der „Qualmgrenze“ damit der Motor überhaupt startet. Ersetzt du jetzt einen Teil der (ideal) angesaguten Luft durch Mölnebel, dann muss er zwangsläufig eine überfettet Verbrennung einleiten. Resultat …. Es qualmtBitte gib mir den deutschen Text, den du übersetzt haben möchtest.

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Unless Möl requires significantly more air for complete combustion than diesel (mass ratio ~ 14.5), and/or Möl has a significantly lower calorific value than diesel.

It would be disastrous if Möl had a higher calorific value than the fuel that is burned in the engine …..
In addition, the air-fuel ratio during Möl combustion is not the same as that of diesel or gasoline. This significantly hinders verschandeln combustion.