Sooo as my wife says I like to fix things until they’re broke! She didn’t appreciate it when I said that’s what she did to me!

Auto diesel. Did the whole manifold out and new glow plugs in etc. all back together and starts up fine apart from a leak from the leak off pipes. So to eliminate all possible causes I put in new pipes and O-rings and the pipes still leak just in a different place or blows off the connection at the one way valve.

I’ve disconnected sections working back to the filter and the flows seems to be ok. Did a leak off test and found that the injectors seem to be ok. Is it possible to have excessive return flow from the other pipes causing the leak off pipes to back up? Am I right in thinking that the return flow back to the tank doesn’t pass through the filter eliminating possible filter blockage?

So completely at a loss now and wondering if anyone else has had similar or is more knowledgable than I? Done a search and can’t seem to find anything similar, apologies if this has already been picked up. Corrado VR6 Mystic Blue - Gone
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Hang on I am getting a remarkable occurrence of Deja vu here...

Literally posted about doing the exact same thing a few days ago - https://www.freel2.com/forum/topic37641-15.html

I put it down to the reduction in ambient temperature I cannot point you in the right direction at the moment, because you are a stage ahead of me. But you have my sympathies and if mine does the same would you mind locating the problem ASAP

In all seriousness. Where does the leak pool or run down? Perhaps degreasing all the pipes, then wrapping with tissue, then electrical tape might work. I have used this on household plumbing to track down radiator leaks. Works a treat in identifying location and narrowing down where the leak begins from.

Ha yeah wasn’t sure if I should have added it your thread, thought I didn’t want a potential take over of your Pheobe thread.

So initially the pipe connection to the one way valve was bursting and then after reconnecting it moved further up to where the pipe connects to the 2nd injector from the left. It’s not a drip type leak as well, a proper squirter and more so under revs.

It still leaks after disconnecting the return pipe from the filter to the tank. So thinking as you have similar it can’t be a dodgy part, can’t be blocked from the filter to tank and so it might be too much fuel being sent to the injectors causing the pressure to build up on the one way valve preventing it from opening to let the leak off pipes flow. Not sure what would cause that though.

Dunno, plumbing is bad enough as it is without the volatile fuels! Corrado VR6 Mystic Blue - Gone
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Oh it also leaks when the leak off pipe set up is disconnected from the other return flow pipe going back to the filter. So scratch the idea of pressure backing up on to the valve. Corrado VR6 Mystic Blue - Gone
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I think you’ll find that the excess fuel from the rail does go back through the filter unit but there is also a temperature controlled bleed of warm fuel back to the high pressure pump via the filter. Once warm fuel is coming from the tank (because what isn’t bled to the hpp goes back to the tank) this bleed is closed off.
Some of the cheaper fuel filters don’t have the bypass which can lead to problems.

Thanks, good to know. The pipes still leak disconnected from the filter suggesting that there is too much pressure build up in the leak off pipes set up. Corrado VR6 Mystic Blue - Gone
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Popped one of the injectors off and took it apart and found no blockages. Back together again and still leaking. Will work through the other injectors when I get a chance. Corrado VR6 Mystic Blue - Gone
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The pressure in the leak off lines on these injectors are held at 10 Bar pressure, which is controlled by a valve in the single line back to the filter.
If there wasn't a leak before the leak off lines were removed, it suggests that some damage occurred to a connector while removing them, which is now preventing them from sealing.

The whole leak off line assembly is available, so it's probably best to just replace it, which would also eliminate an issue with the pressure control valve. Hyundai Ioniq 5 Ultimate. The family car.
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Last edited by Nodge68 on 2nd Dec 2022 5:44 pm. Edited 1 time in total

Yep done that and it’s still leaking. Thinking it’s either too much leak off coming off one of the injectors or a sensor needs replacing.

On the subject, good breakdown of the fuel line and management system given here:
http://mmc-autoelectric.org.ua/manuals/eur...600ENG.HTM Corrado VR6 Mystic Blue - Gone
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Thanks for the system description.

Took the manifold back off to check that I hadn’t pinched a cable or tube. Nothing untoward found all back together and still leaking.

Noticed that when putting my foot on the break to start up a funny electrical noise (like a dud electric door buzzer is the only way I can describe it) comes from the camshaft cover area which goes away when the fuel rail pressure sensor is unplugged. Can’t pinpoint its exact location. Has anyone else got this noise too? Not sure if I’m just noticing it now because I’m looking at the fuel rail sensor and pressure regulator.

Next stage is new fuel filter and checking the fuel rail sensor and regulator. Then if all fails getting on to checking the other 3 injectors. Corrado VR6 Mystic Blue - Gone
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New fuel filter in and primed, bled the fuel system.

Pressed start, engine hesitates, turns over once, and then screeches. Didn’t sound like the the starter motor or belt so not touching it again. Booked in for recovery to local indie. Heart breaking but I guess the risk of DIY’ing Only positive is that the bank is covering the recovery. Corrado VR6 Mystic Blue - Gone
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Recovery and garage booked and with nothing to lose tried to starting her up. Sprung to life with a minor leak at one of the injectors, changed the spill off grommet and no more leaks for now! Putting it down to something being frozen over to make the initial screech noise and an air lock in the rail or feed pipes (did the controversial last resort of cracking the nuts to let out any air out).

So for anyone who comes across leaking/bursting fuel pipes check for air locks Corrado VR6 Mystic Blue - Gone
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