High pressure diesel fuel lines
 

Hi guys,

I recently pulled the valve over off of my 08 xc90, and now I have been told that I have to replace the diesel fuel lines as they are a single use item. I have called and talked to a number of Volvo mechanics in my area and they say that this isn't true and the lines can be used again...maybe even for a third time too.

I was just wondering if any of you can shed some light on this issue as the Volvo dealer days the car will catch on fire if I reuse the fuel lines.

Any help will be greatly appreciated.

Only new fuel lines are guaranteed to seal properly, and replacing them each time is thus recommended by Volvo. Due to the way they deform and seal when tightened up. That's the official dealer line.

Of course, you are free to choose to ignore Volvo's recommendations, and refit your old fuel lines.

This is what the other garages that you spoke to would do.
There is just no guarantee that they will seal and not leak fuel.

It doesn't mean that they WILL leak fuel - it just means the guarantee is not there.

So if you reuse the old fuel lines and they don't leak, then you are fine.
But if you reuse them and they leak, then you need to replace them.

Volvo policy is to fit new lines and with good reason - this ensures that your car will not have any leaks as a result of work done at a dealer.

However in practice, if refitted carefully and correctly the chances of a leak are low. Make sure the joins are clean, tighten them correctly, let the car tick over for 10 mins checking carefully for leaks. Check again after 20 miles or so.

I have reused them on many cars maybe not hundreds of times but certainly tens with no issues.

In addition, be extremely careful that there are no leaks when the engine is running because the diesel is under extremely high pressure , allegedly capable of penetrating skin.:shocked:

Many many on here have reused the existing pipes with no issues whatsoever and that's what I would choose to do if I was doing it BUT it's up to you to decide.

Just ensure everything is done up properly to minimise possibility of leaks if you do decide to go that way.

I refitted the high pressure diesel lines on my similar vintage Accord (Bosch common rail system running at 1600bar) and, despite instructions in the official Honda workshop manual to fit new ones, there were no leaks.

My thoughts were to try it, then replace them if there was any subsequent leaks. A garage would have to get it right first time.

The pressure in the common rail diesel system is considerable when the engine is running.... but the volume of diesel being pumped is very low. Whilst it could easily penetrate skin at full pressure, it would need to be sprayed from a pin hole type nozzle. If the pipes were to leak, the diesel would have to work its way out of the hose union or through the threads by which point it would have lost all pressure and be a "seep". If there was a really bad leak (e.g. open pipe) then the pressure would be very low as the leak volume would be way above the volume the pump is capable of.

So provided you are sensible and methodical, it is safe for home mechanics to work on the high pressure side of the fuel system.

Thanks everybody for your replies. This give me more confidence to reuse the lines.

Just another question...are the lines supposed to be tightened to a specific torque setting or just do them up as tight as you can?

I think there is a torque listed for them but it's tricky to do that with a spanner.....

They don't want to be too tight either, I would try to replicate how tight they were when you undid them. You do not want to be stripping threads on your injectors...

Ok I'll give it a go and let you all know how I go.

Thank you for your help.

I have reused them many times on Mondeo TDCI just keep them clean (IPA, carb cleaner etc) and don't wrench the hell out of them you'll be fine.

Just keep an eye on the threads.