Should you break in a new engine after replacing the turbocharger?

Hello!
My turbodiesel needed a new turbocharger after only 25,000 km (and I also added 5W40 oil). My question is: Does the car, or specifically the turbocharger, need to be broken in now? Should I drive gently for a certain distance (avoiding hard acceleration and high RPMs)? Or do new turbochargers not require special break-in procedures (since the turbo itself already spins at very high speeds, making it difficult to really protect it by limiting its speed)?
Thank you and best regards,
AndréV

Hi, I don't see any reason for that.

christians wrote:

Hi, I don't see any reason for that.

Agreement... on the other hand, one should also avoid high loads immediately after cold starts, also in the interest of the loader's longevity. After all, operating-temperature oil lubricates the loader better than "cold honey."

I haven't really broken in my new head yet!

I simply believe that it should have been possible in 2004 to produce with such tight tolerances that adjustments would no longer be necessary.

And if not, I still have a 24-month warranty!

Regards,

Manuel.

If the turbo is new, it automatically comes with a 2-year warranty.
Okay, let's do this.
I don't think turbochargers are that sensitive because they only rotate in one direction, unlike an engine block.

I simply believe that it should have been possible in 2004 to produce with such tight tolerances that adjustments would no longer be necessary.


Sure, you can do that, but then your engine block will be as expensive as a brand new Audi A6...

'Nothing really works against micro-roughness, and in mass production, there's still a trade-off between quality and quantity. While the machines are now very good, their performance is geared towards high cycle rates. Achieving accuracy better than 1µm is only possible with extreme parts (e.g., injection equipment). And even then, you often need to run test cycles because not every part can be finished perfectly. Take a look at various parts regarding surface treatment. You can estimate the feed rate by counting the grooves on the cutting tool...''Please refer to the post by donalexo, where he described his problems with performance testing a brand new axial piston pump...'

'Proper break-in is essential. That's why one colleague in the workshop needs 1 liter of oil every 10,000 km, while another only needs it every 25,000 km. One of them broke in the engine properly, the other didn't.'

CU Gremlin.

In my opinion, for a new engine, it's sufficient to drive it reasonably for the first 500 kilometers.

My A4 was a rental car from a dealership for 18,000 km, and it only received its first oil change at 18,000 km!

I don't think anyone really cared about the customer needing to get settled in or warmed up.

And the old engine had 236,000 km on it. And I couldn't detect any signs of wear! Of course, I didn't use a precision measuring tool with 0.01mm accuracy! Also, the cylinder bores looked very good!

Break-in period: YES or NO!

As long as you can't produce two identical engines and run one according to the manufacturer's instructions while immediately subjecting the other to full load to determine its lifespan, you will never know whether break-in periods are still necessary today.

But let's get back to the turbocharger:

I say no, because the only period with potential wear and tear is from the initial filling during installation until the oil pressure is established.

Regards,

Manuel.

*dusting*

Now I know that the bearing surfaces operate virtually without contact within an oil pressure cushion, and therefore cannot really wear in due to the lack of metal-to-metal friction.

What about thermal "burn-in" processes?

I once heard that BMW was looking for used cylinder heads, either in Germany or worldwide, several years ago to use them in Formula 1 (?).
The new parts were deemed unsuitable because the internal material stresses caused by the manufacturing process would constantly lead to cracks under racing conditions.
Only parts that have undergone thousands of heating and cooling cycles (and have had their residual material stresses eliminated) should be able to withstand the rigors of racing.

Now I don't know to what extent this principle of aluminum cylinder heads can be applied to cast manifolds and turbocharger housings. However, if it can, then cracks could occur if the engine is warmed up very quickly with the new turbocharger in order to test the turbocharger as thoroughly as possible within its maximum pressure range.

Is there any truth to this idea, or does cast steel behave fundamentally differently from aluminum casting in terms of thermal aging and susceptibility to cracking?

Hello Ulf,

ulf wrote:

I once heard that BMW was looking for used cylinder heads, either in Germany or worldwide, x years ago to use them in Formula 1(?). The new parts were supposedly unsuitable because the manufacturing-related internal material stresses would constantly lead to cracks under racing conditions.

"This concerned the gray cast iron engine blocks of the 1.6 models, which were bored out and, with a shorter stroke (limited to 1.5 liters), mercilessly boosted to produce up to 1200 horsepower in racing applications. Apparently, the factory-new blocks would have exploded under such conditions."
Generally, all cast parts in mechanical engineering are "aged" by placing them outdoors for several months before machining. If it's very urgent, the parts are artificially aged by repeatedly heating and cooling them. I'm sure that turbocharger manufacturers do things no differently. Otherwise, they would have a return rate so high that it could put them out of business.

Quote:

Is there any truth to this idea, or does cast iron behave fundamentally differently from aluminum casting in terms of thermal aging and susceptibility to cracking?

Yes, this behaves fundamentally differently. A turbine housing certainly does not consist of cast steel (which is actually called "steel casting" ), but rather of gray cast iron (you can hear it if you tap it with a screwdriver. If it sounds like "pling," it's steel; if it sounds like "plock," it's cast iron). Also, individual alloys differ in their aging behavior.
But, as I mentioned earlier, the issue with the BMW action wasn't about aluminum; it was about gray cast iron.


Best regards, Uli (I've been driving a 2002 BMW for almost 10 years).

Uli S. wrote:

But as I said, the BMW campaign wasn't about aluminum, but about gray cast iron.

Hi Uli,

Then I probably mixed something up... it's good that you at least remembered the promotion based on the manufacturer .

Quote:

Generally, all cast parts in mechanical engineering are "aged" by placing them outdoors for several months before machining; if it's very urgent, the parts are artificially aged by repeatedly heating and cooling them. I am sure that the manufacturers of turbochargers do not do things any differently. Otherwise, they would have a return rate so high that they could go out of business.

Ah yes.
So, if one wants to be particularly careful (and doesn't entirely trust the loader manufacturer), then it would be advisable to initially "acclimate" a new loader to the thermal stresses on the engine over a few trips before giving it full throttle for the first time?
As I understand it, performing a "thermal break-in procedure" might help reduce the statistical probability of cracks occurring in the manifold/charger.


And now, for something completely different (off-topic), since it's relevant right now:

Quote:

Yes, that is fundamentally different, as a turbine housing certainly does not consist of cast steel (which is actually called "steel casting" ), but rather of gray cast iron

. Hmm, so in the TDI engine, you have material pairings of gray cast iron / aluminum / gray cast iron from the block to the cylinder head and exhaust (turbocharger), with significantly different thermal expansion coefficients (if I recall correctly) and corresponding shear stresses on the seals.

Why not simply cast the cylinder head from gray cast iron?
For a diesel engine, those few extra kilograms wouldn't really matter, but the effort required to develop correspondingly robust seals could potentially be kept much lower?

Hello Ulf,

If I understood my master correctly,

The zero-crossing detector (ZK) may shift significantly from its reference area (ZKD), which is made of aluminum, due to thermal deformation.

-> Grooves or striations present within the soft connective tissue.

\\speculate

However, this seems to be something people are willing to accept, as using a gray cast iron head might require accepting larger 'clearances' against the gasket, which would mean compromising the cylinder head gasket's lifespan, potentially leading to it failing more frequently (perhaps every 50,000 miles).

Hello Ulf,

Quote:

Then I probably mixed something up... it's good that you at least remembered the promotion based on the manufacturer.

"Back then, an autocross driver told me that he heard I had thrown away an old 1.6-liter engine block. Of course, it was too late by then, which is why I still remember it (I never forget things that are too late; on the other hand, I often forget things that might be important for the future...). Just to be sure, I did some googling so I wouldn't spout nonsense here ".

Quote:

If you want to be particularly careful (and don't completely trust the loader manufacturer), then it would be advisable to gradually acclimate a new loader to the thermal stresses on the engine over a few trips before giving it full throttle for the first time? As I understand it, performing a "thermal break-in ritual" might help reduce the statistical probability of cracks appearing on the manifold/charger.

"On my Golf Mk2, an exhaust manifold cracked once; it was already 12 years old at the time. My brother had a similar issue with the exhaust manifold on his 90hp Mk2 Golf, which was also about 10 years old. I believe that local temperature differences during operation are more damaging to these parts than any residual stresses from the manufacturing process. With an engine block for a racing turbocharger, it's different; it's subjected to extreme mechanical stress rather than temperature fluctuations, so there can't be any residual stresses in it."

Quote:

Hm, so that in the TDI engine, from the block via the cylinder head to the exhaust (turbocharger), you have material pairings of gray cast iron / aluminum / gray cast iron, with significantly different thermal expansion coefficients (if I recall correctly) and corresponding shear stresses on the seals.

Okay. Assuming a motor length of 40cm and a temperature increase of 100°C, the aluminum head would theoretically expand by 0.95mm, while the cast iron block would only expand by 0.42mm. However, the exhaust manifold is likely to get hotter than the head, so it may expand more than the head itself.

Quote:

Why don't they simply build the ZK (presumably a machine or component) out of gray cast iron?

due to heat dissipation. In the past, car cylinder heads were also made of cast iron, for example, in the Mini and some Opel models. However, this is no longer a good option with a certain engine displacement; gasoline engines are then prone to knocking, and diesels...? Actually, it's not such a stupid question; I understand it with a sleeve valve engine, but with a direct injection (DI) engine? The cylinder head wouldn't get that hot .

Best regards, Uli.

Hello,

"The stresses within the gray cast iron are correct. The same applies to machine beds; they are often stored for a longer period before being machined. If not, they can warp later like a bow. Therefore, the best approach for a turbine gray cast iron housing would be to let it sit undisturbed for a few years after installation..."
Therefore, an old spare part that has been stored for a long time is not necessarily bad either.

Zu der Verwendung von Aluköpfen gibts hauptsächlich zwei Gründe. Das eine ist die Wäremleitfähigkeit da im ZK viel mehr Wärme abgeführt wird als im Block, zum anderen sind weit mehr Gleit und Dichtflächen im ZK genau zu fertigen. Das geht in Alu weit schneller und billiger. Ausserdem lassen sich im Alukopf Alu/Stahl Lagerflächen herstellen, wo bei Guß jedesmal eine Lagerbüchse aus Rotguß oder ähnlich gebraucht wird. Innere Spannungen und Verzug ist bei Alu ein besonders Thema, das hängt extrem von Legierung und Wärmebehandlung ab. GenAluminum is less durable than gray cast iron under temperature fluctuations, but it seems sufficient for the statistical lifespan of a car.

Best regards,
Christian.

Uli S. wrote:

Assuming a motor length of 40cm and a temperature increase of 100°, the aluminum head would theoretically expand by 0.95mm, while the cast iron block would only expand by 0.42mm. However, an exhaust manifold will certainly get hotter than the head, so it may expand more than the head.

However, the manifold will not always expand or contract in perfect synchronization with the cylinder head. Consequently, bending and shear stresses are exerted on the manifold studs practically with every temperature change.
Could this be the reason why bolts might shear off easily after a certain amount of use during an exhaust manifold/turbocharger replacement, even with relatively low loosening torques ?

Assuming that the relative movements caused by thermal expansion are greatest on the outer surfaces of the manifold and engine block, it also makes sense that one of the outer bolts sheared in your case, as described in the link.

Is there any specific technique for installing the crimp screws, or any other tricks to minimize the problem?