Fuel Injector Leak Test: On-Vehicle Inspection?

I have a Volkswagen Golf 2.0 TDI, manufactured in 2008, with the BMM engine, and it currently has 130,000 km on the odometer.
The fuel injectors were removed by a VW dealer at 100,000 km and ultrasonically cleaned. New valve seats were installed, but the injectors themselves were not otherwise refurbished.

I'm only interested in knowing now whether the nozzle's tightness can also be...
I can't check it while it's installed. I don't want to have to do that again.
have it expanded.

By the way, my VW dealer told me that he doesn't check the injectors for leaks.
it can be checked, whether it's installed or not. Maybe the Bosch service department could do it?!

My suspicion is that my engine, when it has been turned off for a short period (3-10 minutes) and then restarted, starts up very "explosively" - the first few piston strokes when it starts are quite forceful/strong.
Furthermore, after 7000 km, I found 10% diesel in the oil. However, the tandem pump has already been replaced, and the common rail injectors have also been re-sealed.
It could also be a leaky nozzle.

But - as I said - I only have ONE question here:
Can the fuel injectors be tested for leaks while they are still installed in the engine?

Quote:

I'm only interested now in whether it's possible to check the nozzle's tightness. can be checked while it is installed.

Not really. You can only be sure about that on a test bench.

Possibly, the injector nozzle may not be completely sealed, causing diesel fuel to drip into the combustion chamber.
It is difficult, or even impossible, to prove this through measurement, or one can use a suitable camera to look into the combustion chambers after a certain period of operation.

Autoservice wrote:

Quote: I'm only interested now in whether it's possible to check the nozzle's tightness. can be checked while it is installed. Not really. You can only be sure about that on a test bench. Possibly, the injector nozzle may not be completely sealed, allowing diesel fuel to drip into the combustion chamber. It is difficult, or even impossible, to prove this with measurements, or one can look into the combustion chambers with a suitable camera after a certain period of time.

Thank you for the response.
€630 as compensation.
and 750 euros per piece for a new one is just way too expensive for a quick purchase.
Have all four replaced to see if it makes a difference, for approximately €3500, including labor and taxes.

I'm currently seeing some on the website for €245, and they're coming from England.
"New part in original, unopened packaging."
Hm....

Let's check if any cylinder is significantly misfiring using the idle speed control.

Check measurement block 13 in the engine control unit using VCDS.

Best regards, Rainer.

dieselschrauber wrote:

Let's see if we can identify any cylinders that are significantly out of sync using the idle speed control. Check measurement block 13 in the engine control unit using VCDS. Best regards, Rainer

Yes, thank you - I could do that again, I had completely forgotten.
I had already logged this issue over a year ago for the same reason.
but only minor (imagined) anomalies were detected...
I'll do it again.

I recorded my starts for half a day.
Okay, so always follow this procedure before starting the engine:
Ignition on - VCDS channel 13 selected - Log file specified - Log start - then turned the ignition key fully to start the engine - then stopped the log after approximately 1-2 km.
The intervals between the log entries were short, approximately 3-8 minutes.
Exactly the operating times that normally cause this "undesirable" "explosive" behavior were in effect. And it was very hot that day.
Well, I'm not sure what to make of the logs; everything looks quite normal to me. Unfortunately, I don't have any reference points from other engines, and I don't know which values are considered "normal" here.

Hello,

It's enough to just look at the values when the engine is idling; they are not alarming and are actually relatively good.

Best regards, Rainer.

Hello,

What does the engine temperature do? If the engine control unit (ECU) believes the engine is cold, it will increase the fuel injection quantity and advance the start of stratified injection, which can cause a "rough" warm start.

I would rule out a leak from the pre-combustion chamber to the combustion chamber, as in such a case, exhaust gases usually enter the fuel supply (at the bottom), and the engine occasionally stalls at idle (which has already happened).

Yes, it's me again...

The problem is getting worse and worse.
The engine temperature is fine - the values are "consistent".

I'm considering replacing all four PD elements again.
I don't know what else to do.

The PZT elements were already ultrasonically cleaned and resealed.
At 100,000 km - now I have 140,000 km on it.
But there's a problem with diesel fuel getting into the engine oil (0.5 liters every 7,000 km).
And this extremely abrupt and explosive start-up behavior has consistently worsened over time, never improving.

On Monday, I'll get a quote for the cost of replacing the 4 PD elements.
I'm delivering them. I just saw a Bosch dealer selling them for 300 euros each.
New product, not refurbished, and no need to return any old product.

I bought a boat and I'm launching it into the water using a steep ramp.
Water. If the car is then turned off on the steep ramp, and approximately...
If it's restarted again 5-8 minutes later, the problem is very severe.
Often, the engine starts explosively, only to immediately stall with a strong jolt.
Then, sometimes it takes a second, third, or even fourth attempt before it finally starts up again, requiring a vigorous shaking for about 1 second.
It's always very intense on the steep ramp - so it's quite something.
Whatever the reason, it makes a difference whether the car is parked straight or not.
on the slope.

I can only imagine that the diesel is leaking from the dripping nozzle.
In the tilted cylinder, the oil is more likely to remain in a puddle on the piston rather than dripping onto the flat piston surface, where...
It can escape downwards more easily through "leaky" piston ring gaps.

Okay, even though I'm probably going to look like a fool here and make a complete idiot of myself...
I had the four glow plugs replaced, along with the wiring harness, and while they were at it, they also replaced the spark plugs.
Nothing has changed - not in the slightest.

The car starts "forcefully" and "explosively" when restarted (when warm) after a standstill period of 1-10 minutes.
I don't know how to describe it better than with these words.
It feels like the starter motor is turning the crankshaft 1 or 2 revolutions further than usual - then there's a "thump" with a strong jolt, and it starts running...
At the gas station, post office, and when launching the boat, I don't even bother turning the car off for a short time.

For me, the only options are 1. to sell the car or 2. to continue replacing individual components - but the question is, which ones?

Please check the plausibility of the values from the wheel speed sensors and the crankshaft sensor.

If it requires 1...2...3 rotations, I would suspect a missing or faulty signal from that component.

Or, inspect the northwest encoder wheel. Check if all 'corners' are present and straight. Verify that the encoder values are correct.

Has this ever been swapped out by chance?
I think the valve timing is correct, right?

mullemaus wrote:

Please check the plausibility of the values from the wheel speed sensors and the crankshaft sensor. If it requires 1...2...3 rotations, I would suspect a missing or faulty signal from that component. Or, inspect the northwest encoder wheel. Check if all "corners" are present and straight. Verify that the encoder values are correct. Has this ever been swapped out by chance? I think the timing is correct, right?

He certainly doesn't need three more revolutions than usual.
Two is almost an exaggeration coming from me.
The starter motor has to run for a bit longer than usual before the engine starts with a "thump." I've gotten used to holding the ignition key in the "start" position for a little longer – maybe 1 second longer. You can easily tell this by the fact that if someone else starts my car, they usually make a failed start attempt first because they tend to release the ignition key too quickly.

The car drives exceptionally well - the acceleration, top speed, and fuel consumption are all as good as they could be.

No, nothing has been done to the crankshaft, sensor wheel, or camshaft yet.

Can I read out, log, or control these values in a measurement block?

Sorry, I've basically given up hope, but one thing is certain:
still occurred to me.

I've had a weasel in my engine compartment quite a few times, and as I and my mechanic see it, nothing has ever been seriously damaged.
Here and there, you might find small scratches from teeth or claws, and of course...
Kot und Essensreste. Ich hab ja jetzt seit 1Jahr eine Marderabwehr (Highvoltage) drin. But...

Which intake or pressure hose, if it had a small hole, could cause symptoms like the ones I'm experiencing?
I only experience this rough, jerky start when the engine is warm.
And as mentioned above, the starter motor also needs to rotate a bit further/more than it normally would before it "jerks" (engages) forcefully.
Is there a hose that I should have checked?

I'll be taking the car back to the workshop soon, and I'll...
Mullemaus said to have the wheel speed sensors and crankshaft sensor checked for plausibility.
and also have the northwest sensor wheel inspected.

It was the starter!!
He barely reached the minimum speed required by the control unit to inject diesel (when the engine is warm).
I actually only came across it when I randomly saw a diagram posted by user "mgor".
I saw it on motor-talk.
Then my doorbell rang.
It's a shame that I only came across it so late - and then by chance...

Since today, I have a new starter motor - the car is unrecognizable, everything is perfect!

Thank you for your feedback .

Well... if you had used the search function, you would have definitely found the starting speed mentioned in this forum as well.

Your descriptions like...

Quote:

Then the second, third, or sometimes even a fourth attempt until it finally starts working again, with a strong shaking for 1 second. It's always very intense on that steep ramp - so it's quite a ride. Whatever the reason, it makes a difference whether the car is parked straight or not. at the incline.

... also naturally lead us astray. In addition, there is the oil dilution and the explosive start-up, which is often followed by the engine dying.

As far as I've experienced, the affected engines then start when the start authorization is given. However, they usually do so as if nothing had happened.
Perhaps there's still a minor issue lurking that doesn't seem significant now.

The ways of the Lord are sometimes unfathomable .

Autoservice wrote:

Thank you for your feedback . Possibly, there's still a minor issue lurking that doesn't seem significant now. The ways of the Lord are sometimes unfathomable

.

You've hit the nail on the head - that's exactly how it is.

The car now starts perfectly.
You can't let go of the ignition key fast enough, it starts so quickly.
"Just put the key in and it starts – whether it's warm or cold, a significant improvement compared to before, where everything felt like it was happening in slow motion."

But...
Even a tiny "hiccup" – a minuscule "irregularity" in the initial piston strokes – can still be noticed if you pay very close attention, and you'll know what to look for.
That was probably what skewed the "starter" diagnosis earlier, because it was much more pronounced.

Okay, I'll just let it go. As you said, it's not that important anymore. If I took it to the workshop, they'd think I was crazy.