Golf 1 GTD: Bleed Fuel System - How To

Hello everyone.

I own a Volkswagen Golf 1 GTD and I'm having the following problem.

Der Golf lief etwas bescheiden, also hab ich den Förderbeginn kontrolliert und korrigiert. Als ich dann wie immer das Kraftstoffsystem entlüften wollte, hat das leider nicht geklappt, da die Batterie zu schwach war. Also aufgeladen und erneut versucht. Wieder ohne Erfolg. Batterie wieder geladen und jemand anderes starten lassen um im Motorraum zu schauen was passiert. Ich habe dann die Luftblasen in der Zuleitung verfolgt und da fiel mir auf, dass die Luftblasen immer wieder zurückschwimmen Richtung Kraftstofffilter und in der Mitte der Zuleitung stehen blieben. Jetzt dachte ich: länger orgeln lassen bringts. Also gemacht, bis die Batterie zu schwächeln begann. Die Luftblasen waren fast alle verschwunden, doch als nicht mehr gedreht wurde, kamen die Luftblasen wieder Aus der Kraftstoffpumpe zurück und jetzt steht wieder Luft in der Leitung. Jetzt hab ich mich gefragt, ob es sein kann dass die Kraftstoffleitung irgendwo verstopft ist und die Pumpe quasi ein Vakuum saugt und deshalb nicht zu entlüften ist. Oder ist einfach die Batterie zu schwach dass ich nicht lange genug drehen kann? I've bled and adjusted the pump several times before, but this time something seems to be wrong.

I hope someone has some advice.

If you need more details, just let me know.

Best regards, Willi.

Hello!

I wouldn't do that at all. It puts unnecessary stress on the battery, starter motor, and ESP system.

You can fill the ESP (Electronic Stability Program) reservoir with verschandeln diesel fuel and using a verschandeln container/funnel, syringe, or similar tool. Pour it into the return hose fitting until it's completely full, then screw it on tightly, and the engine should start immediately.
Then let's see what happens.

It would be even better if you have a suction pump or can obtain/borrow one. Heating technicians should have something like that for filling oil lines. Alternatively, there are also manual pumps available for transferring liquids.
This allows you to connect to the pump's return line and draw diesel from the tank through the filter and into the ESP (Exhaust Gas Recirculation) system.
This method effectively and gently removes air quickly and also helps to identify leaks.

I assume you are familiar with the common problem areas on the fuel filters. (Specifically, issues like cracked housings, damaged connectors, torn water drain valves, and rust).

I have a rubber hand pump at home for bleeding brakes.

I'll temporarily connect to the inlet line before the catalytic converter (ESP), pump until everything is full, let it run for a short time, and then disconnect it.

It is standard equipment in many older diesel engines from France.

In your case, it is advisable to vent the nozzles during the startup process.

If the injectors are empty, loosen the corresponding union nuts while the engine is running to allow diesel fuel to leak out.

Otherwise, you might end up waiting a long time, and you could even burn out the starter motor of your classic car.

Best regards, Rainer.

First of all, thank you for responding so quickly. So, the fuel filter and its connections can be ruled out because everything was replaced six months ago. The ideas about pre-filling, etc., are of course ideal, and I feel really silly that I didn't think of it myself...

"The last time I tried to bleed the fuel system, I loosened the fittings on the injectors. Diesel was leaking from the first injector (which is the number 4 cylinder - furthest to the right). I tightened the coupling nut and that seemed to fix it. No diesel leaked from the other injectors."

Okay, I'm going to try using a vacuum system. I have a hand-operated vacuum pump for bleeding brakes. I'll build an adapter and connect it to the return line and see what happens. I'll let you know how it goes.

Thank you again for the helpful suggestions.

If you only checked the start of the funding period, then you likely removed the sealing screw just to insert the measuring device. After that, a new seal was needed, which you certainly installed.
Normally, after venting the high-pressure side, the engine starts almost immediately. The pump does not run dry.
What else was done?
hg
Herbert.

Hello!
Let's deviate from the question for a moment:
I've never personally seen a turbodiesel engine in a Volkswagen Golf 1 that I could be sure was the original engine from the factory.
Retrofitting is already done.
Lt. Wikipedia gibt es das schon, ab 1982. The MKB would then be CY.
Do you have one of those with the original engine?

Ich frage nur deshalb, weil ich techn. Interested in...
and even owned a Golf 1 diesel, a Golf 2 GTD, and a T3 turbodiesel himself.

It's great; answering questions like these makes you feel 20 years younger!

And now, back to the original question:
You mentioned that the golf game was a bit underwhelming.
The start time of the ESP (Exhaust Gas Recirculation) actually only changes with the wear of the timing belt drive, but you don't really notice it. And not very quickly. Once it's properly adjusted, it stays relatively stable for the entire lifespan of the timing belt.
Please also consider that it might be due to air being sucked into the fuel supply line.
I believe the diesel lines leading to the tank are made of steel, and they can corrode. You'll likely see a damp spot there, but it doesn't necessarily have to be dripping visibly. However, even with that, air can still be sucked in.

"The Golf 1 had metal fuel tanks. I'm afraid I don't remember the exact details of how the diesel intake worked, but gasoline models often had an air filter in the intake line, which could sometimes become clogged with rust. Keep that in mind as well, just in case you run into problems. If the ESP (evaporative emissions control) system is drawing fuel and the tank can't supply enough, it can also cause leaks elsewhere, such as at the connections between rubber hoses and metal pipes."

You'll notice leaks at the fuel injection pump if you see something dripping. There are several potential leak points that can cause starting problems, especially if the engine has been off for a while. However, once it starts, it should run properly. Because the fuel injection pump mainly operates under pressure, and fuel tends to be pushed outwards rather than air being sucked in.

Well, I'm quite confident that the combined expertise here in this forum can help you solve your problem.

To Herbert: That's exactly what surprises me. Usually, after I start it, it always starts up right away. The only time it took longer was when he got the new pump.

I understand that the start of the boost cannot be adjusted. I just recently had the timing belt removed due to the intermediate shaft, and then probably didn't pay close enough attention to it when setting it up initially. The seal is new, and the pump seems to be tight so far. I will now try using a vacuum to ensure the system is airtight, and if that doesn't work, I will check the lines leading to the tank and the tank itself.

Regarding the car itself: The Golf was originally available as a Turbo Diesel, which was then called the GTD. Unfortunately, this isn't an original one, as the bodywork was no longer usable. Now, the engine is installed in a Golf 1 diesel body.

Hello everyone.

Okay, I finally had some time to work on my car, so I bled the fuel system. All of the bleeding attempts were done using a vacuum pump.

I started by checking the fuel pump's return line.
After that, I reversed the process, submerging the return line in fuel and drawing it through before the diesel filter. However, I could never get all the air out of the leak-off lines. So, I removed the plug on the first injector at the back, connected a hose to it, submerged the other end in diesel, and then drew fuel through it using the return line. That's how I managed to remove the air.

Then came the attempt to start it, but without success...

So, I removed the fuel lines from the injectors to see if any fuel was actually reaching them, and sure enough, only the rightmost injector (cylinder 4) is receiving diesel. All the other lines remain dry.

Does anyone have any idea what this could be? I know that remote diagnosis is always difficult, but maybe someone has a suggestion.

Next, I will check to see if I made a mistake when setting the start time for the process.

Have a nice evening, and thank you in advance for your help.

Greetings, Willi.

Hello Willi,

Either the injection pump is not properly filled with fuel, the feed pump inside the injection pump is defective, or the springs on the pump plunger are broken. When attempting to start the engine, fuel must be coming out of all four injector lines, not just one.

Best regards, Rainer.

"Trying to bleed the system with vacuum won't work anymore; you need to actively bleed it with pressure. I'm going to connect a rubber bellows pump and use it to push diesel through the entire system. If it's very difficult to pump, try adding more pressure, then start the engine. While it's running, loosen the injector fittings and release any remaining air from there."

If the engine still doesn't start after using the standard bleeding method – applying vacuum to the return line – then there are essentially only three possibilities.
- Shut-off valve does not open.
- Injection timing is significantly misadjusted.
- The ESP is not building up pressure; there's insufficient high pressure.
To remove air bubbles from the suction side, simply compress them with pressure. However, to remove air bubbles from the outlet side, using vacuum is the recommended and more effective method by the manufacturer.
The return connections of the individual nozzles and the connection to the EGR (Exhaust Gas Recirculation) system are interconnected.
hg
Herbert.

The question is whether the suppressor is sufficient.

I'm pumping the diesel through filters and a pump, and instead of compressing air bubbles, it's being pumped back towards the tank.

The hand pumps in older inline fuel injection pumps operate in the same way.