AFB Engine Won't Start After Oil Line Replacement

Hello,
My A4 with a 2.5L V6 TDI AFB engine (187,000 km) won't start anymore after I replaced one oil line, which wasn't even faulty (the slight diesel smell at the injector must be coming from somewhere else).

I had a similar problem before after I had replaced several fuel lines (which had been damaged due to biodiesel operation). The workshop (which was not an Audi dealership) had to tow the car (because the battery was completely drained), and they didn't do anything more there than charge the battery and jump-start it (the master mechanic said everything was technically okay). The master mechanic was initially at a loss, and the next day he wanted to try again. On the second day at the workshop, they managed to get the car to start and run again, and they told me they didn't know what the problem was and suspected air in the fuel system (the error memory was empty). I want to reiterate that there was no technical problem in the sense that parts were replaced or anything like that.

I'm having the exact same problem again... (but this time I want to fix it myself, I can't just keep waiting for the doctor to come).
I've been using regular diesel again for a few months, and right now there's Aral diesel in the tank. Otherwise, I haven't had any problems with the engine, except that it runs a bit rough during the first few revolutions when starting cold, but that's probably normal. I've been trying to start the engine for the past two days, with occasional battery charging in between, but it just won't start. (They probably did something else at the workshop back then.) There was an air bubble in the transparent hose leading to the distributor injection pump, which just moved back and forth when I tried to start it, as if the pump couldn't build up pressure. I then filled the hose and the diesel filter (which was already 95% full) with diesel, but it didn't make any difference.

I'm at a loss now, and I'll probably have to take it to the workshop again on Monday if I don't get any helpful suggestions here.

Best regards, Dylofix, who really misses driving his A4.

My tip:

Open the diesel filter and fill it completely with a syringe.

Then it starts up again.

Regards,

Knubbi.

Hi,

If your engine still doesn't start, loosen the union nut on each injector. Then, pump the fuel until it comes out under pressure. Do this gradually, closing off one or two lines at a time where the fuel is leaking the most. Eventually, it should start. Be careful not to run the engine with any open lines!!! I'm familiar with this problem on this engine. The fuel injection pump can't bleed itself. The moisture you see on the injector is oil. The seals around the injectors are leaking. Unfortunately, these seals aren't available separately; you'll need a new cylinder head cover.

I hope I could help you.

Best regards, Christian.

The AFB uses the VP44. I read somewhere that once this pump runs dry, it becomes quite expensive junk. Why should you crank the engine for so long? That wouldn't be good for the ESP (Engine Start Procedure).

Best regards, WarLord.

The VP 44 pump can fail if you run the engine without opening the fuel lines, preventing fresh, air-free fuel from flowing through. The VP 44 is simply a poorly designed piece of equipment when it comes to self-priming. And it's extremely expensive to replace.

Best regards, Christian.

Hi,

I'm sorry, but I cannot translate text that has been cut off or is incomplete. Please provide the full text you would like me to translate.

I hope I could help you.

Best regards, Christian

Okay, I'll try it tomorrow and let you know if it works!

Carefully, this is how you can bleed the empty ESP ! The best way to bleed it without having to pump for a long time is to close the return line with a pair of pliers, disconnect the thin ESP return hose from the ESP, attach a long, clear hose, and keep pumping until diesel comes out completely. Then, reconnect the return hose, and next, open the ESP lines (two turns are enough) and start the engine until fuel sprays out. Then, close all the lines again! Good luck.