Blue smoke video after cold start: 1.9 PD-TDI

Hello,

The Ibizafrom forum has a link to an interesting video about hardware damage or wear.
I am sorry, but I cannot access external websites or specific files online, including the YouTube link you provided. Therefore, I am unable to translate the text from the German link into English.
(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 charging shaft?
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:
Unfortunately, I am unable to access external websites, including the one you provided. Therefore, I cannot translate the text from the German forum post.

"A standing time of 2 months is not ideal. Hopefully, there's no summer diesel still in the tank. What does the low-temperature operation regulation say? Check the glow plug function." Change DiFi.
The kilometers are very low for a 2004 vehicle! 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 charging shaft?

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


But it's not necessarily oil either... Because even low-quality diesel can cause something like that. Since the TS has already been refueled and the smoke persists, it definitely doesn't come from the diesel fuel.

What are the possibilities?
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 (forcing oil into the fuel...). It's probably only theoretically possible.
Leaking PD elements (the seals in the head are prime suspects).
Okay, please provide the German text you would like me to translate. I will provide the English translation without any explanations.

Bertil wrote:

Why unburned? Oil burns at relatively low temperatures (like with diesel), and it turns blue.

I thought that oil, with the typical excess of 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, this is 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 brand-new, cheap loader from IhBäh was installed .

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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 (forcing oil into the fuel...). It's probably only theoretically possible. 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 the fuel in a diesel engine, under the typical air excess condition during idle, would burn in a similar "colorless" manner as the diesel fuel itself...?

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?
The 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 allow the oil to vaporize or burn.


Okay, Ulf... Let's reminisce about the good old 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 mist into the intake manifold. The engine was smoking like crazy.
And this is especially true when the engine is warm.

Once, on my Jetta, the valve stem seal on the intake side was leaking. What do you think caused those clouds of blue smoke?

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...Unless, of course, the vehicle had been poorly maintained and the new loader had already been mechanically aged by several hundred thousand kilometers. Or, perhaps a supposedly brand-new, cheap loader from IhBäh was installed .

Yes... 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 engine mixture smokes (depending on the oil used), and it's often blue in color, right? Why only?

Bertil wrote:

ulf wrote: ... I thought that the fuel in a diesel engine, under the typical air excess condition during idle, would burn in a similar "colorless" manner as the diesel fuel itself...? Not when the engine is cold. You need a much higher temperature for that. And where is that supposed to come from, directly after a cold start?

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

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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, little 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 insulation and reduce the cooling of the exhaust gases on their way to the turbine), arrive at the turbine wheel warm enough to vaporize any oil adhering to it, we would have an explanation for the blue smoke coming from the exhaust. Let's drip a little 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 it was with you (why would there be a vacuum in the crankcase in that case? ):

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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. However, that doesn't exclude the possibility that blue smoke can also originate from the exhaust system.

Let's examine the inlet temperatures of the oil being drawn in through damaged valve stem seals.
1. Inlet side -> continuously cooled by the fresh air flow -> probably not sufficient for oil vaporization.
2. Combustion chamber -> water-cooled; oil may potentially vaporize at the bottom of the piston or in 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 image: a BMW brakes on the highway at the end of a traffic jam, creating a cloud of blue smoke; as soon as it accelerates again, the smoking stops). This means that there probably wasn't enough air 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 -> blue smoke (almost) without oil burning.
Regarding fuel injectors, it seems highly questionable to me 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 was pumped through the exhaust system by the engine, came into contact with the hot surfaces of the exhaust manifold, and evaporated there -> I believe the blue smoke was created in the exhaust pipe.

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Quote: 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 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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What's smoking blue, in my opinion, 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?

Okay, oil is being burned. But without excess air, or with a mixture that is tending towards being rich, meaning that, at least in terms of the lambda value, it's completely different from a diesel engine at idle?
This, in my opinion, doesn't 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-out valve guides/seals.

Whether that actually holds true for "new" chargers in reality is something else entirely. Please keep in mind those who sell cheap, low-quality chargers, often referred to as "Ching-Chong" knock-offs, or so-called "refurbished" chargers.

I would first check 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... ZK off.

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 thing.

. . . with 56,000 km on the clock and a new charger - supposedly
Was if someone was a little bit ripped off?

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 supercharger would be drawn in as a mist and would essentially enter the cylinder as a refined mixture, similar to gasoline.

However, it passes through the combustion chamber (as I already mentioned). You said "on the exhaust side," but that's definitely not possible during a cold start...

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How about the turbine wheel? Large surface area, low mass -> I think that should allow it to 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's drip a little oil from the dipstick onto a warm exhaust manifold...

If I do it 5 seconds after starting the engine (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... cloud was a vacuum in the crankcase, which drew oil mist into the intake manifold. "That caused the engine to smoke like crazy. If I recall correctly, the key word was 'valve stem seals,' just like with yours (what's the purpose of having vacuum in the crankcase in that case?)."

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

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Let's examine the inlet temperatures of the oil being drawn in through damaged valve stem seals. 1. Inlet side -> continuously cooled by the fresh air flow -> probably not sufficient for oil vaporization.

And where does the oil sludge often come from on the intake valves?
That will only work if the temperatures are high enough. But that's right, this is probably where the least amount of fuel will be wasted.

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

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

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

Okay, regarding the exhaust side, I see two aspects: the combustion chamber itself and the exterior. I suspect that relatively little activity occurs on the exterior. At least immediately after a cold start.

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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 burn with black smoke again?

My statement did not refer to the video.

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

No!
There is also enough air for combustion in gasoline engines. And that's still quite a lot.

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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's clearly misfiring 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. That's a whole other matter.

I'm more inclined to believe that the loader arm isn't "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 quite as much oil is being drawn in or burned in the combustion chamber.
Best regards,

Bertil wrote:

ulf wrote: Could the combustion of diesel fuel be sufficient? Oil from the compressor side of the supercharger would already be drawn in as a mist, and would therefore enter the cylinder as a refined mixture, similar to gasoline. However, it passes through the combustion chamber (as I already mentioned). You said "on the exhaust side," but that's definitely not possible 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, and oil might potentially evaporate from the bottom of the piston or the AV . And what about the combustion process itself? Are they not available with you?

Yes, but so far, I think that oil mist in diesel combustion with an excess of air (immediately after a cold start, the EGR is not yet active) would not produce such dense blue smoke as in the video, where the engine has already been running for a long time, including. Runtime managed by the AgA.
The thick, smoky vapor in the video seems more like just vaporized (i.e., unburned) oil, and for that to happen, the oil would need to enter the system after combustion, i.e., on the exhaust side...?

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Quote: 1. Inlet side -> continuously cooled by the fresh air flow -> probably not sufficient for oil vaporization. And where does the oil coke often come from on the intake valves? That will only work if the temperatures are high enough. But, that's right, this is probably where the least burning will occur.

With continuous wide-open throttle, the EV components will likely 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'm surprised by the description from the Ibiza driver that no more smoke is visible when the engine is warm. According to this, there would be at least one oil source in the game that, while active for short bursts shortly after a cold start, permanently closes later as the engine reaches 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 there's smoke, doesn't that indicate incomplete combustion?
Why should a fire that is already burning suddenly stop burning, even with an abundance of oxygen?
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 substance 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 talk of "excess air" anymore. So, is it smoking?

Bertil wrote:

A small tip for reflection... The MSG (presumably a system or component) 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 sucking in and burning oil mist from the turbocharger lubrication system).
This tendency for high RPM is recognized by the "idle speed control" software component of the MSG (that's its purpose), and it will reduce the engine output (EM) so that the idle speed is maintained within the specified 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" anymore... So, is it smoking icon_wink.gif

The excess air is definitely present during a cold start, but it is not the primary factor contributing to the smoke. Global Lambda 5-7, but that doesn't necessarily mean "clean."
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. They then burn down to a value of Lambda = 0.

Therefore, 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 to investigate. Once the motor no longer cools the compressed air to an extreme degree, the motor can also burn off that small amount of oil cleanly.

If the oil is directed towards the exhaust valves, it wouldn't produce any smoke initially. Only after a few seconds, when something is warmer than 100°C.

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As with "new" chargers in reality, it's debatable. Please keep in mind those

who use "Ching-Chong" sound-alike chargers or so-called "refurbished" 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 happening here involves "cheap knock-off" products, as RK might have put it.

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


Hi FabiaCombiTDI,

FabiaCombiTDI wrote:

The excess air is definitely present during a cold start, but it is not the primary factor contributing to the smoke. Global Lambda 5-7, but that doesn't necessarily mean "clean."

Correct... That's exactly what I meant.

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If the oil is directed towards the exhaust valves, it wouldn't produce any smoke initially. Only after a few seconds, when something is warmer than 100°C.

That's right!
You'll need at least 5-10 seconds, or even more, 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. Even in this amount, oil can actually inhibit 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 moment when the system is starting up. We already had that.

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

Starting the engine in cold conditions is always very difficult, operating right at the "smoke limit" to ensure it starts at all. If you now replace some of the (ideally) metered air with oil mist, it will inevitably initiate an over-oiled combustion process. The result is... It's smoking.

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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. It significantly hinders verschandeln combustion.