Mal wieder ein V6 TDI mit Problemen | Posts 16+

I'm quite familiar with aluminum brazing. However, the issue with the oil is no longer relevant. There's a product called 'aluminum brazing wire.' You can use it for normal brazing, to fill in broken corners, and even to seal cracks (it's flux-cored). I used it to make some brackets for my motorcycle radiator.

But with the thin wires in the control unit, that probably won't work. They'll melt before you even get started.

Okay, here's a really dumb question. You bought a diesel car that's about 7 years old with around 70,000 kilometers on it. Is that understandable/reasonable?

Yes, the mileage is understandable because it's now 186,000 km.

Take a look at the date of the first payment.

And what exactly does that change regarding the traceability of the product at the time of purchase? It was just an idea anyway.

I bought the Passat in 2007 with 35,000 kilometers on it, not 7 years and 70,000 kilometers. But we're getting off topic.

ok, my mistake. Sorry.

I have another question. What is the typical engine speed when using the starter motor? On Friday, I recorded data while starting the engine. Over those 5 seconds, it only reached 106 RPM. Is that normal, or is it too low?

Far too little .

What does the pump status indicate under MWB 018?

MWB18 doesn't indicate anything. Otherwise, there would be an error stored in the memory.

Okay, so I tinkered around a bit today. The static setting of the pump is correct; nothing seems to be out of place there. I took a look at the camshaft through the oil filler neck, and it doesn't appear to have moved. With a second battery, the engine speed during starting is 162 RPM. The O-ring on the screw on the left side of the pump is now new. It didn't look defective, and it was still as soft as the new gasket. Then I used a vacuum pump to suck out 2 to 3 cups of diesel through the return line. Afterwards, I disconnected and cleaned the lines on the right-hand side of three injectors, and good diesel came out. More than last week during the first test. While doing that, it sounded like one cylinder briefly ignited. There's definitely no air in the supply line. Today, I also read that a proper pre-lift pump was installed starting in 2003. That one is also working because last week, when trying to start the engine with the return line (ESP - DiFi) disconnected, a good amount of diesel sprayed out of the reservoir.

I'm slowly getting to the point where I don't know what else to do. I'm also not sure if it's the pump.

I can do a test tomorrow. I still have some fuel injectors here. I'll connect one to a line and see if the pump builds up enough pressure to even open the injector.

Neither 162 RPM nor 106 RPM will start the engine.

Well, the batteries weren't really fully charged anymore. I've also had another car jump-start it before. However, I didn't record that information. What is a typical cranking speed?

If the starter motor wasn't installed in such a hidden location on the V6 engine, I would have removed it a long time ago.

Diesel-Dirk wrote:

... What is a typical starting speed? ...

> 280 rpm. This generally only applies to a warmed-up engine.

Thank you for the information.

With a fully charged battery, the starter motor achieved 186 RPM today. From the sound it makes, the engine has always sounded like this when starting. Nevertheless, I took the part out and disassembled it. I couldn't find any obvious faults. The brushes still have 75% of their material remaining. The commutator looks good. Based on what I've read recently, the magnetic switch might have an increased resistance and be causing a voltage drop.

What still worries me is the engine's hesitation when accelerating. It happened before, right before it stopped starting altogether. I experienced something similar when my ESP system failed. The only difference is that this time there's an error code stored in the diagnostic memory.

Can the ESP (Electronic Stability Program) diesel fuel contribute to the ESD (Electrostatic Discharge) without a controlled high-pressure solenoid valve? Or does the diesel flow directly into the return line? Because diesel fuel does reach the ESD components. I'm just not sure if the pressure only comes from the fuel tank pump and the vane pump.

So, der Passat läuft wieder. It was the ESP.

Here's some additional information for troubleshooting. Hopefully, it will be helpful to others.

Ich hatte mal eine Einspritzdüse frei hängend angeschlossen. Beim Startversuch kam kein Tropfen Diesel raus. Also hat die Pumpe keinen Druck aufgebaut. Dann hab ich das Steuergerät der alten ESP, die ich noch hatte, aufgemacht und erstmal nichts auffälliges gefunden. Die Drahtbrücke zw. Platine und Transistor, die bei anderen durchgebrannt ist, war bei meiner Pumpe doppelt vorhanden. Das müsste der Source-Anschluß sein, über den der Strom zum Magneventil fließt. Naja, an dem Steuergerät hab ich das Löten porbiert. Ist wirklich nicht so einfach. Mit einer dicken Lötspitze hab ich dann doch den Lötzinn an die Kontakte bekommen. Nur an den kleiner Anschluß für das Gate hab ich nichts ranbekommen. Im Net hab ich ein Bild gefunden, dass die Gate-Anschluß auch an so einem großen Kondensator angeschlossen werden kann. Das hat auch funktioniert. Nun hab ich das Ganze auch an der noch eingebauten defekten Pumpe gemacht. An der war auch kein Defekt zu entdecken. Erstmal ein paar Drähte dran und den Transistor freiliegend angelötet. Nach ein Mal Zündung an, ist das Ding sofort so heiß geworden, dass sich das Kabel am Drain sofort selbst abgelötet hat. Also wieder angelötet und den Transistor auf ein Aluklotz geklemmt. Das hat dann ein paar Sekunden länger gehalten. Wurde aber auch wieder zu heiß und das Drain-Kabel ist wieder abgefallen. Aber dabei ist mir was wichtiges aufgefallen. Mit den Transistor hat das Magnetventil getickert. Dieses Tickern hat die Pumpe sonst auch gemacht, wenn man die Zündung eingeschaltet hat. Nach dem der Motor nicht mehr ansprang, hat die Pumpe keinen Mucks mehr von sich gegeben. Also nun stand fest, die Pumpe ist kaputt. Also erstmal mit der alten Pumpe zum Boschdienst gedüst und gegen eine Regenerierte getauscht. Over the weekend, I installed it and noticed that the currently installed, defective pump was harder to turn than both the new pump and the old, defective one, even when turned only halfway.

My conclusion is that tinkering with the pump control unit is pointless. If the transistor fails, it's usually due to mechanical issues. Furthermore, having a professional repair the control unit doesn't make much sense either. The only solution in such cases is a refurbished pump.

It's also noticeable now that the engine runs smoothly again when it's idling. Apparently, the stiffness of the pump caused regulation problems and ultimately led to the transistor being overloaded.

Now, this new pump also needs to last for another 100,000 kilometers, and then everything will be fine.

And thank you to everyone who tried to help with advice.

Best regards,
Dirk