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Jonhamil

Bleeding / Priming Diesel system N47 2.0D 5 Series Following Injector Service

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So I have stripped down and cleaned my injectors which has meant disconnecting the common rail for about a week. 

 

According to ISTA+ I'm getting about 8 bar on the common rail when in ignition and 15 bar when cranking. I have used the ISTA+ bleeding procedure. I have also attached a hand pump to the fuel return line on #1 injector while running the lift pump via ISTA+  there were lots of small bubbles but by the time I finished it was running clear - I did not repeat for the other injectors though.

 

Looking online, looks like I need a Sealey VS555 or similar to bleed all the injectors and the whole system at the point where the clear fuel return line connects to the black fuel return line on the RHS of the engine bay.

 

Does anyone have experience of bleeding an N47 (piezo injectors) after a loss of fuel or injector replacement please? Any tips very gratefully received :-)

Edited by Jonhamil

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is it not a self bleed system? i don't know about bleeding the injection system, but after replacing the fuel filter you don't need to bleed it - you simply turn the ignition on and leave it for a minute or 2 to self prime.

 

I could be wrong and you need to bleed out the air between the pump and the injectors, but i don't know. 

 

 

looking in newtis it doesn't mention any bleeding is done when injectors are removed/replaced. 

Edited by dj1233

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How did u fix your problem Jonhamil? I have same problem with bleeding my n47 engine. Removed rocket cover gasket. And can't get any diesel to injector lines. I get diesel from the line that is coming form the High pressure pump, but i dont get any out of the rail. 

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On 8/12/2020 at 4:55 PM, dj1233 said:

is it not a self bleed system? i don't know about bleeding the injection system, but after replacing the fuel filter you don't need to bleed it - you simply turn the ignition on and leave it for a minute or 2 to self prime.

 

I could be wrong and you need to bleed out the air between the pump and the injectors, but i don't know. 

 

 

looking in newtis it doesn't mention any bleeding is done when injectors are removed/replaced. 

Self bleed works fine for things like fuel filter swap etc but isn't up to the job when the high pressure fuel rail is disconnected. See this:

 

 

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10 hours ago, ChristianB said:

How did u fix your problem Jonhamil? I have same problem with bleeding my n47 engine. Removed rocket cover gasket. And can't get any diesel to injector lines. I get diesel from the line that is coming form the High pressure pump, but i dont get any out of the rail. 

Hiya, sorry I thought I had updated all the threads I had commented on and forgot this one. It's all fixed, here's how:

 

 In case it helps anyone in the future. I had to manually bleed the diesel lines. There are multiple ways to do this - the way I did it was to get a second set of leakoff pipes and use a vacuum pump (this one from Amazon: https://amzn.to/3qatbBK) to draw the diesel through. The auto-bleed of the engine isn't sufficient if the common rail has gone dry.

 

I used ISTA's bleed function to operate the lift pump and drew through from the engine. Did this roughly 4 times - each time the pressure at the common rail raised up. After the 4th time, it hit 600 bar (measured via ISTA), car would not start. I turned off and on again and car started - and ran really sweet

 

Ista's bleed function is quite easy to find and well documented on the web. Ista's common rail measurement display is harder to find. You have to go to the component tree that it displays after scanning the car, click on the diesel ECU (I think it's DDE from memory) and go to measurements and highlight them all, then press update and you can see all fuel pressures.

 

For me it happened just like the guy in the video said. I operated the lift pump via ISTA, then the vacuum pump for the full 3 mins that ISTA runs the lift for. Then turned it over and saw the common rail pressure increase. Then repeated - in the end 4 times. After the 4th time, it hit 600 bar - at which point you know it's bled to the common rail. I then excitedley tried to start the car and it failed - on reflection this is because the very last part of the system is now bleeding - the injectors themselves. I then turned it off, left it for 1 minute and tried again and it fired into life.

 

Top tip - definitely make sure your battery is in perfect condition before doing this lol.

 

Hope that helps?

 

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Hi @Jonhamil

 

I'm currently having to do this procedure on a N57 (six cylinder) after replacing the fuel pressure / temperature sensor before fuel reaches the hpfp.

 

I have the same equipment mentioned but when i activate the pump I can hear the air in the system gurgle but the bottle that comes with the pump fills up with air and fuel then overflows causing fuel to leak out over the handle, i have to stop the pump at this point however it still draws more fuel (clear of air).

 

I've done this on the first 3 cylinders and only see 1.4 to 2.5 bar, The pre supply pressure is reading 0.0 mbar.

 

Unfortunately my battery has given up for today and may also need replacing. The issue stems from the sensor I had to replace originally giving up and sending fuel back to the ECU via the loom. Although i am also planning to replace the ECU I want to check this side of the work is done. The engine had run previously with the faulty sensor and whilst diesel reached the ECU, its been cleaned out with contact cleaner - no signs of burns and it still seems to function and be read.

 

Any help would be great. I would take it to a garage but its xDrive and due to the way it's parked there is no access to switch it into neutral from underneath :(

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5 hours ago, Nathan505 said:

Hi @Jonhamil

 

I'm currently having to do this procedure on a N57 (six cylinder) after replacing the fuel pressure / temperature sensor before fuel reaches the hpfp.

 

I have the same equipment mentioned but when i activate the pump I can hear the air in the system gurgle but the bottle that comes with the pump fills up with air and fuel then overflows causing fuel to leak out over the handle, i have to stop the pump at this point however it still draws more fuel (clear of air).

 

I've done this on the first 3 cylinders and only see 1.4 to 2.5 bar, The pre supply pressure is reading 0.0 mbar.

 

Unfortunately my battery has given up for today and may also need replacing. The issue stems from the sensor I had to replace originally giving up and sending fuel back to the ECU via the loom. Although i am also planning to replace the ECU I want to check this side of the work is done. The engine had run previously with the faulty sensor and whilst diesel reached the ECU, its been cleaned out with contact cleaner - no signs of burns and it still seems to function and be read.

 

Any help would be great. I would take it to a garage but its xDrive and due to the way it's parked there is no access to switch it into neutral from underneath :(

Hi Nathan

 

Thanks for your comment. I definitely found you need the battery to be in tip top condition before doing this otherwise you can get some odd results.

 

I'm not entirely clear on the issue you're having - if you activate the hand pump on each injector, you should draw fuel through each one which should then start to fill the bottle attached to the pump. You seem to be saying that there is no fuel going into there but it is leaking elsewhere? A Photo would really help buddy :-)

 

Perseverance and relentless cold hard logic was the way out of this one for me if that's of any help..

 

 

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So the problem I had was the fuel temperature / pressure sensor on the fuel line had failed. Diesel was sent up the wires in the loom and flooded the ECU.

 

I've now replaced the Battery, DDE and fuel line/sensor which lead to air in the rail - I bled it using the methods mentioned above for cylinders 1,2 and 3..  that being if 1 was the closest to the nose of the car. 

 

First time cranking with replacement DDE the car fired up, coughed, spluttered then stalled. And since it's almost started but I don't want to overdo it.

 

Fuel rail pressure when off is 4-6 bar and reaching 70 to 90 whilst cranking..

 

Should it drop to 4-6 bar when off?

 

Thanks for any advice

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4 hours ago, Nathan505 said:

So the problem I had was the fuel temperature / pressure sensor on the fuel line had failed. Diesel was sent up the wires in the loom and flooded the ECU.

 

I've now replaced the Battery, DDE and fuel line/sensor which lead to air in the rail - I bled it using the methods mentioned above for cylinders 1,2 and 3..  that being if 1 was the closest to the nose of the car. 

 

First time cranking with replacement DDE the car fired up, coughed, spluttered then stalled. And since it's almost started but I don't want to overdo it.

 

Fuel rail pressure when off is 4-6 bar and reaching 70 to 90 whilst cranking..

 

Should it drop to 4-6 bar when off?

 

Thanks for any advice

Hi Nathan

 

Sounds like you're almost there. Here's what I would do..

 

1. Charge the battery overnight - get it 100%

 

2. Bleed out all 4 using the manual pump + Ista activating the lift pump method

 

3. Turn it over again

 

4. Repeat 2 & 3 another 2-3 times and watch the rail pressure increase each time. When it hits 600 bar - give it a rest for a minute. Then turn over again - it should fire up. If it doesn't, give it another rest for a minute and try again. Remember not to turn over for more than 10s continuously or you risk overheating the starter motor. 

 

Let us know how you get on fella - good luck :-)

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