V6 Engine Won't Start: Fuel Pump Replacement Failed?

Hello,

I hope one of you can help me with the following problem:

A while ago, my Passat simply stopped working while I was driving. I called the ADAC (German equivalent of AAA), and they determined that the VP44 pump, or more specifically, the quantity control valve, was faulty.

My workshop confirmed the analysis and replaced the pump; then, at VW, the immobilizer was adjusted, but the engine still wouldn't start. After a compression test performed by , it was determined that the pressure was only between 8 - 19 bar.

So, I took the vehicle back to my workshop, where they started looking for further issues. According to their diagnosis, there are no errors detected, and the fuel injection pump/injection timing is fine.

Now the mechanics are stuck and want to remove the cylinder heads because they claim the valves are completely carbonized.

The vehicle is a Volkswagen Passat 3BG with a 2.5L V6 TDI engine, manufactured in late 2002.

Thank you in advance.

Camshafts flattened!!?

EDIT: Did you instruct the workshop to replace the pump, or were they only instructed to find the fault?
If the former, it went wrong.

In the other case, they should investigate why the device isn't working. If the problem wasn't caused by the pump, then it's not your fault, and they should fix the issue.

Okay, the workshop has created a cost estimate of over €2400,-, but they don't guarantee that the vehicle will then actually run.

The following causes are likely:

- Intake ports of the cylinder block are clogged.
- Individual valves with carbon deposits.
- 1 x faulty hydraulic lifter and rocker arm (making improper contact with the camshaft).

Here's a possible reason why it might not be starting. The question is, why was the system working perfectly before the ESP was replaced, without any hesitation or loss of power?
Only the ADAC technician attempted to get the vehicle running on-site using a jump starter before diagnosing a defect with the ESP system; otherwise, no further action was taken.

Unfortunately, there was no written order, so the workshop is claiming that the pump was replaced and considers the matter closed.

The vehicle is coming to me now.

Furthermore, the camshaft kit was replaced by Volkswagen as part of routine maintenance at approximately 40,000 kilometers and still appears to be in good condition.

The following errors have been ruled out by the workshop:

- Intake manifold flap
- Start of injection.
- ESP
- Head gasket
- Injector valves
- Spark plugs

What I also don't understand is why no errors could be found during the diagnosis.
The vehicle cranks and cranks, but it doesn't start .

Hi there,
Are the valve timings correct?
By the way, the action

Quote:

had attempted to get the cabin running using Startpilot on-site before diagnosing the ESP as defective; otherwise, nothing further was done.

is not exactly made of cardboard. The engine ran flawlessly (or maybe it did), before it stopped.
There's nothing against the roadside assistance services, but my family members have strict instructions to decline everything except for jump-starting in case of a breakdown.
Sure, here is the translation of the text from German to English:

"vg" translates to "very good" in English.
Herbert.

The valve timing is correctly adjusted.

Could the actions of the "Gelbe" (Yellows) possibly have led to a defect?

Hi,
That question cannot be answered like that.
Regarding the general use of starting fluid or brake cleaner as a starter fluid for diesel engines, you can find quite a bit of information using the search function.
Sure, here is the translation of the text from German to English:

"vg" translates to "very good" in English.
Herbert.

Okay, so I've looked at the forum posts about the "Startpilot" issue. The symptoms described there don't seem to apply to my vehicle. The engine turns over normally when starting, without any noises or anything like that, but it just won't start.

Hi,
The statement about the compression is very inaccurate. What are the values for each cylinder? Can't the workshop that is now going to overhaul the cylinder heads first check the compression themselves? And then again after the repair? It's outrageous to have one workshop check the compression and another repair the cylinder heads. Then no one takes responsibility. You can already see this with the ESP and the immobilizer system.
If you disconnect the fuel injection lines at one or more injectors, will diesel fuel leak out when starting the engine?
It would also be interesting to know how the workshop ruled out some of the potential causes (e.g., fuel spray start, injectors).
Sure, here is the translation of the text from German to English:

"vg" translates to "very good" in English.
Herbert.

Okay, so the workshop is an independent repair shop. After replacing the fuel injection pump, the vehicle was taken to a Volkswagen dealership where the fuel injection pump was adjusted for the immobilizer system, the start of injection was set, and a compression test was performed.

1. Cylinder pressure: 5.5 bar.
2. Cylinder: 7.9 bar.
3. Cylinder: 11.9 bar.
4. without a test.
5. Cylinder pressure: 19.8 bar.
6. Cylinder: 9 bar.

After that, the workshop re-examined the vehicle, as it had already failed to start at the Volkswagen dealership, and they concluded that the problem was likely due to a dirty cylinder head or carbon buildup on the valves (as seen through an endoscope).

There's no guarantee that the vehicle will be working again after the repair to the engine head, as the workshop isn't certain. However, they definitely want to be paid for the work they do, and that's also my problem.

I'm not going to pay for something that probably won't work. By the way, the vehicle has been there for 8 weeks because they seem to be working on it only when they have time.

When the nozzles are removed, a significant amount of fluid also comes out; of course, the seals were replaced each time. Furthermore, VW inspected the pump and confirmed its proper function before any adjustments were made.

Hello, the compression is definitely not okay.
Have you ever tried letting it roll downhill? If everything here is correct, that should work. Then you can rule out some potential defects.
"Now that the new Nockies are installed, someone needs to explain to me how a lever can possibly come loose."

Hi there,
die Verschleißgrenze für den V6 TDI Motor dürfte wie beim 4 Zyl. bei etwa 19 bar Kompression liegen. Mit den gemessenen Kompressionswerten ist der Motor also überholungsbedürftig, laufen kann er mit einem Zylinder bestimmt nicht mehr. Womit wurde überhaupt gemessen, und warum nicht auch der 4. Zylinhe?
If the compression was measured correctly, the question then becomes how the compression loss occurred.
A sudden loss of compression, as you describe it, is not conceivable without another mechanical defect. Blocked intake ports or leaky valve seats typically manifest gradually, with a progressive decrease in performance and difficulty starting.
Therefore, in addition to the causes mentioned by the workshop, the following may also be possible:
- Incorrect valve timing (due to incorrect settings, loose timing belt pulleys, or a slipped belt).
- Valves are misaligned and hitting the piston crown (this only happens with severely incorrect valve timing).
- hydraulic leveling elements (all defective? or perhaps just empty?);
- Defective camshaft;
- Faulty latch levers (all?)
- Piston rings leaking (all of them?)
- Pistons burned through (all of them?).
- Intake manifold, e.g., throttle valve.
- Exhaust system to (catalytic converter; particulate filter).
My advice, if you don't do the repair yourself: Take the car to a single workshop that is responsible for both the measurement and the cylinder head overhaul. If the workshop of your current choice cannot check the compression of the engine, it certainly isn't the right choice for overhauling the cylinder head. The responsibilities are already messed up as they are now, and if things continue like this, your engine will be ruined too.
The procedure before a ZK (likely referring to a Zenith Kardan coupling) overhaul should be approximately as follows:
- Check all ZR wheels to ensure they are properly seated.
- Check and, if necessary, adjust the valve timing.
- Inspect hydraulic elements, rocker arms, and camshafts.
- Check the compression of all cylinders according to the manufacturer's specifications (RLF).
- If the compression is poor: a) Possibly add a little oil to the affected cylinder and recheck the compression to rule out worn piston rings. b) Consider using an endoscope to inspect the piston crowns and cylinder walls.
- Check the intake and exhaust systems, and if necessary, repeat the compression test with the exhaust manifolds removed.
Dann kann über Überholung des oder der ZK´s in derselben Werkstatt entschieden werden. Weiteration:
- After removing the cylinder head, at least visually inspect the cylinder bores and piston crowns.
- After the cylinder head repair, the compression must be checked again and should be within acceptable limits. The workshop guarantees this.
Of course, other defects are also possible, such as poorly trained workforce.
Sure, here is the translation of the text from German to English:

"vg" translates to "very good" in English.
Herbert.

What does "strahl" mean in this context? Are the nozzles exposed in the room, or just the pipes?

The valves were already carbonized before the damage occurred, but the engine was still running.

If a cylinder still has some compression, it should be audible when running.

"How do you want me to check the start-up sequence when the engine isn't running?"

If you're not confident in your own abilities, take the car somewhere else entirely. Try another Volkswagen workshop or a Bosch service center. Independent garages often struggle with these types of issues.