has various diesel leak issues

I note that the forum bot has automatically reduced my original post. The ELM question is related to various diesel leak issues that I am having and now I have to type everything out again.
- I replaced my diesel return line late last year
- the car was fuming diesel at the end of March
- I got it to the mechanic around May / June who then replaced all 4 injector seals
- that lasted a week and then it started leaking again.
- took it back 2 weeks ago and he repaired a seal where the diesel supplies the injector (I think it was injector 3)
- car currently doesn't want to ignite
- it came back from the mechanic with a new rattle that the turbo specialist says is the cat convertor
- the specialist also found multiple faults related to fuel pressure, fuel sensor control circuit low, Fuel regulator
- reverse gear now also has a terrible chugging sound and the car has power dips - mostly In reverse gear.

I would like to diagnose the precise problem before swapping out parts that may or may not solve the various problems. A regulator is £59 and a sensor is £14, so it quite a difference for what appears to currently be a guess.

Hi

DevineSA wrote: ↑Fri Jul 31, 2020 4:27 pm I would like to diagnose the precise problem before swapping out parts that may or may not solve the various problems. A regulator is £59 and a sensor is £14, so it quite a difference for what appears to currently be a guess.

Yes, you need to diagnose the problem. The fault codes do not always point to a faulty sensor. The code fault codes are generated when the ECU sees a parameter from a sensor that is out of an expected range. This may be due to a faulty sensor, but it may be caused by a fault condition and the sensor is reporting the information correctly.

DevineSA wrote: ↑Fri Jul 31, 2020 4:27 pm I note that the forum bot has automatically reduced my original post. The ELM question is related to various diesel leak issues that I am having and now I have to type everything out again.

OOPS. If it may have stripped out a two question post.

DevineSA wrote: ↑Fri Jul 31, 2020 4:27 pm - I got it to the mechanic around May / June who then replaced all 4 injector seals
- that lasted a week and then it started leaking again.

Is it leaking from the 'leakoff' return pipe? - low pressure diesel or is it leaking common rail high pressure diesel?

Did he replace the 4 copper fire seals?

DevineSA wrote: ↑Fri Jul 31, 2020 4:27 pm - car currently doesn't want to ignite

Does that mean the engine won't run?



With those faults and the miles travelled, I would do a 'diesel injector leakoff test (information here)' to check the state of the injectors before changing any parts.

The leakoff topic is for the 16v, but the same theory applies to the 8v.

Doing this can save a fair bit of diagnosing.

Thank you so much for your response.
- at present the car doesn't start at all. I gave the battery a charge over the weekend. The ignition tries to turn the engine over but it simply doesn't start. On the odd occasion it does successfully ignite and start, it seems to "fade" quickly and cuts again quickly - like it's getting no diesel.
- Not entirely sure what you are referring to when you mention leak-off pipes. From what my mechanic explained to me the diesel going to the injectors is under pressure and then there are another set of low-pressure pipes that return excess diesel back to the fuel tank. We replaced the return system pipes late last year and they do not appear to be part of the current problem - as best as I understand the situation.
- Seeing as the car literally won't move at the moment, I might have to try the injector leak-off test myself. My mechanic has replaced all four seals (1 per injector) where the injector sits on the cylinder. THEN he changed 1 seal on 1 specific injector (No: 3 I think) where the fuel is supplied to the injector.
Hope that clarifies your questions.

DevineSA wrote: ↑Mon Aug 03, 2020 2:16 pm - Not entirely sure what you are referring to when you mention leak-off pipes. From what my mechanic explained to me the diesel going to the injectors is under pressure and then there are another set of low-pressure pipes that return excess diesel back to the fuel tank. We replaced the return system pipes late last year and they do not appear to be part of the current problem - as best as I understand the situation.

The low pressure fuel return pipes are the leak-off pipes - they are the same thing.

There can be a problem of 'excessive leakoff'. There are plenty of pictures in the post that C3CAR linked to above that show what the 'excessive leakoff' looks like.
This can inhibit starting by causing a low pressure in the common rail.


Why did you change the 'return system pipes late last year'?
it is not very common to have to change them and as they don't cause a problem. When they leak it shows that there is a potential problem with the injectors themselves, not the leakoff pipes.

Worn injectors create excessive leakoff and the leakoff pipes - do just that, leak. People replace them when they leak, but not look at what caused them to leak (sometimes, more fuel returned that can be taken by the return pipes causes them to leak because an injector is faulty).

DevineSA wrote: ↑Mon Aug 03, 2020 2:16 pm I might have to try the injector leak-off test myself.

This is something that can be done yourself and doesn't need any special equipment, but this leakoff kit does make it much easier.

DevineSA wrote: ↑Mon Aug 03, 2020 2:16 pm The ignition tries to turn the engine over but it simply doesn't start.

Back to the start
does the engine turn over quickly?

if it doesn't turn over quite quickly, there won't be enough pressure in the common rail and the ECU won't supply fuel to the injectors.

DevineSA wrote: ↑Mon Aug 03, 2020 2:16 pm My mechanic has replaced all four seals (1 per injector) where the injector sits on the cylinder. THEN he changed 1 seal on 1 specific injector (No: 3 I think) where the fuel is supplied to the injector.
Hope that clarifies your questions.

YES. It does. Thank you.

the 1 per injector seals that sit on the cylinder don't leak diesel but when they fail you get a 'chuffing sound' when its running. The link has a video to the chuffing sound a diesel makes when the 'fire-seals' have failed.

Why did you change the 'return system pipes late last year'? - Apparently one or more clips that connect the pipes to the injectors were broken. The pipes were fine but the clips had failed.

Thank you both for your input. LOTS to think about and experiment with. Will have to set aside a few days while juggling my day job. Step 1 - figure out why it's not starting.

Will have to wait around 20 days for my Lexia to arrive. Not sure what I can achieve without it BUT I suppose the vehicle isn't moving anyway.