high pressure injector pipes leaking randomly

[nemesis0124]

2007 W906 311 sprinter

hi
im having problems with the high pressure injector pipes at the injector end leaking randomly, ive tried 2 different sets and even if i get them to stop leaking after a random amount of time or miles one or more start leaking. ive recently done trip of around 350 miles, once i returned i checked the pipes and they were all completely dry.
A few days later i went on a short trip and after stopping to do one of my regular checks on the engine i noticed that one of the injector pipes were weeping diesel. Im 100% sure its not the return pipes its definatly the high pressure pipes at the injector. Just wondered if anyone had any ideas why its doing it and if their was any way of stopping it?

 

[mersum1es]

picture would be nice... those leaks are just coming and going.. if they start to leak, they do leak...

Even a tiny scratch on conical sealing surfaces of pipe fitting will cause a leak. In my previous job we had an experimental egine where we builded common rail fuel lines of out own, and there we could confirm that theory many times If culprit is pipe side surface, you could try gentle sand paper grindig (keep it clean!) or buy a new pipe. If it is injector side, you can buy a fitting also ( I assume here leak IS between pipe end).

 

[nemesis0124]

The leaks are always at the injector side at the collar,either weeping down the threads and collecting on the top of injector or coming up the sides of the pipe where it goes through the collar. The seats aren't sealing properly. I just don't understand why they are leaking after they were sealed

 

[carat 3.6]

Your sure it's not the injector itself leaking? It's rare but they do sometimes crack where the union is.

 

[nemesis0124]

Its not just one injector that does it unfortunately

 

[carat 3.6]

Its not just one injector that does it unfortunately

And the unions are all tight? A conical seat like those shouldn't weep at all, and for all of them to do it makes me think there is a mis-match of pipes to injectors or they are not tight enough.

It wont be over pressure causing it.

Post up a pic if you can as that is a very strange fault.

 

[nemesis0124]

ill try and get picture tomorrow, ive made sure they are tight and tried not to over tighten them but cant seem to find the correct torque setting. They have been on and off a few times due to problems with the injector seats and copper washers. However now the injector washers are sealing im left with the pipes leaking every so often.

 

[carat 3.6]

ill try and get picture tomorrow, ive made sure they are tight and tried not to over tighten them but cant seem to find the correct torque setting. They have been on and off a few times due to problems with the injector seats and copper washers. However now the injector washers are sealing im left with the pipes leaking every so often.

I'm not sure if there is a torque setting for the unions, if there is I've no idea how you would apply it. You would need to be a complete animal to over tighten those.

 

[jc651]

Replace the pipes if they have been off and on a few times...... you can get away with it twice if your lucky but after that the ends will not seal because they are designed to squash seal but once they have been done a few times the ends flatten out and loose there shape hence why yours are leaking. They are not badly priced and replacing them will cure your problem.

 

[Jobsworth]

Crank them up a bit tighter