V6 BDG Compression Issues: Why It Happens?

Hi,

had here: https://community.dieselschrauber.org/en/viewtopic.php?t=24683

I wrote about my problem and now I'm having a compression test done to investigate the poor starting behavior in the morning.

Well, the result is quite bad for an engine with 140,000 kilometers on the clock.
I have attached the document in question.

What surprises me is that the seats on the left-hand side of the vehicle (rows 4, 5, and 6) seem to be consistently getting worse?
Can carbon buildup cause the ventilation to be worse in cylinders 4-6?

I'm not sure if I should just start firing people next.
Do you perhaps have any other tips? (Besides getting rid of the cart )

Okay, yes, the idle speed control indicates that a cylinder is performing better than the reference cylinder when it shows a negative value, right?
The largest deviation I observed after the start was in cylinder 5, where it showed a negative value of approximately -0.39 to -0.55 when the engine was warm, compared to a value of 6.
The cylinders, however, have the worst compression, and their power output might not be more than 2 or 3.

Best regards, Steffen.

The difference is significant; maybe we should start by removing the lids.

However, that's quite intense.
Yes, I suppose I'll have to.

I find this continuous decrease from 4 to 6 quite strange.
It's already quite full of grime, but I wonder if that could have any significant effects?

[Theory] Does the cylinder head have sufficient oil pressure? If not, the hydraulic lifters will remain "soft," the intake valves will open only slightly, resulting in limited airflow into the cylinders, and consequently, the compression pressure will be low.

From the other thread:

exciter wrote:

He also mentioned the battery, which has now been in the car since 2005.

What about the battery? Could it be that it has gradually deteriorated from cylinder to cylinder?
Have you measured (or had measured) the voltage each time the motor spins up?

Why wasn't the measurement taken with a warm engine?

The values are quite poor, but according to the datasheet, they are within the tolerance. The maximum allowable deviation for this motor is 5 bar, and you are not exceeding that. I don't think your problems are related to compression!

Hi,
The wear limit is likely to be below 20 bar for the BDG as well.
If a cylinder head is completely clogged, it could be due to the timing of the coolant water pump for that head.
hg
Herbert.

Hello, the Bosch service installed a starter.
The wear limit is 24 bar, and I'm sometimes already below that.

The temperature was measured because the first start of the day is often not ideal. It occasionally smokes and takes longer to start.

It's quite obvious that something isn't right, because the idle speed values after the start are also not good.

I can't say anything about the oil pressure. Everything looked good when I checked the injectors.
How can I measure the pressure inside those components? Wouldn't that cause them to rattle or make noise?

exciter wrote:

The wear limit is 24 bar, and I am sometimes already below that.

You don't know that at all! It is measured with a warm engine, and since that wasn't done, it doesn't tell us much.
But, as I said, I consider these values to be completely unremarkable. I've already had several V6 engines with pressures as low as under 20 bar, and they still started up and ran fine.

What about the valve timing? When does the injection start?

Quote:

The wear limit is 24 bar,

Where did you get this value from?
For a direct injection system, I would expect a value between 18 and 20 bar. A 5-bar limit for the pressure difference is also typical.
hg
Herbert.

"Hmm, the timing hasn't been checked yet. We replaced the belt at 118,000 km. Everything was connected using original VAG tools. It didn't start better or worse after that. They didn't do a good job with the injection timing. In the basic setting, it's at 0.2° before top dead center (BTDC), and it needs to be adjusted again."

I've now received a new battery from the workshop for testing purposes. However, I don't think it's any better.

The workshop said it, and I found the same information on various websites.
27-31 bar (new), 24 bar (wear limit).

Something different.
Based on how you're describing the start, it's likely that most of your glow plugs are already defective.
My AKE (presumably a vehicle model) also started the same way, and after only 100,000 kilometers, 4 out of 6 glow plugs were already faulty.
completely non-functional.
Testing is very easy; simply attach a + cable to the spark plugs.
If it doesn't work, the candle is defective.

They were replaced last year, apparently only five because one wouldn't come out. The workshop has now drilled out and replaced that one. So far, it hasn't been smoking again when starting. It might also be due to the new battery, because I had the same smoking issue in the summer, and the spark plugs aren't needed then.

I'm going to drive another 900 km today, I'll let you know how it goes.

Okay, I did it...
It ran normally and started well.

However, what I've noticed is that he seems to be swallowing more.
"Normally, I was getting under 7 liters per 100 kilometers on the highway, with a maximum speed of 160 km/h, but now I'm using 8.2 liters?"

I've now put on the 205 size winter tires, but they can't possibly use more than a liter of fuel, right?
Does Bosch adjust the characteristic curves of the pump during a test?

Certainly, all the screws on the control unit component have been coated with sealant.


edit: I just found this now:

http://www.motor-talk.de/forum/aktion/Attachment.html?attachmentId=681731

Therefore, is the wear limit at 17 bar and not at 24 bar? What is correct ?

Does anyone have a current Rep.Faden / Elsa thread and can tell me where the wear limit is?

17 bars or 24 bars?
Starting Thursday, I will be back home and will then remove the protective covers.

Pass auf, wenn die Karre neu ist, haben alle Zylinder min. 30 bar gleichmäßig. Selbst wenn alle Zylinder "nur" gleichmäßig 24 bar hätten, würde der Motor voll funktionieren. Die Unterschiede der einzelnen Zylinder sind hier dein Problem. Man kann nicht behaupten, von 24 bar nochmal 5 bar abzuziehen, wäre in Ordnung. Das isThat's wrong.
The wording in the repair manuals is not precise. The problem is a combination of the overall height and the difference between the cylinders.
Your blood pressure readings are currently within the acceptable range, but you definitely won't be winning any awards for them.
a) I would repeat the measurement with a slightly warmer engine.
b) Lower the hoods and have a professional check them.