brianrheffron

Hi Paul,
I haven't done this job myself yet. I am only passing on
information I have gleaned from others with most help
coming from Brett plus some research on my own.
Look at any moden car and you will see Nylon 12 pipes.

The link shows Chrysler/ Mercedes approval.

http://www.arkema-inc.com/pdf/techpoly/machrysler.pdf

jmartins

I have a similar problem with my car at return line, some small holes. I made a sleeve covering all holes, but I'll order a new return line soon.

jpitman2

If by 'retunr line' you mean the steel line from front to rear, to fit in one piece will require dropping the rear suspension, as its laced between the body and the cross member. I suggest you splice in a new piece and seal with compression fittings.
jp 83 Euro S AT 53k

Maybach_Man

Hi Paul

Let me know if you decide to go with the flexable lines and fittings, as i would be interested for my cars

Geoff

UKKid35

Big Thank You to Geoff for the copper pipe.

Not going to win any prizes, but it doesn't leak

finally!

I personally would not cut and splice. Too likely getting gook, rust, etc. in the line...

UKKid35

No cut and splice involved, I've replaced 928 356 057 00 which is 3 foot pipe with bubble flares on each end and a couple of bends. It costs $220 for the original item. The copper was a gift and the flare nuts were a few $.

Even so I was careful because it is down stream of the fuel filter. However, I ran the pump for some minutes to check for leaks using a relay jumper, this probably would have returned any debris to the tank rather than get anywhere near the injectors.

jpitman2

I cut and spliced a genuine pressure line because I could not lace it through from rear to front in one piece. Did it several years ago now, no issues whatever. Made the cut with proper tool (no internal debris produced) off the car, fitted in place, joind, tested, no problems.
YMMV
jp 83 Euro S AT 53k.

Brett928S2

Hi

I would replace that with the new nylon stuff, the reason we never use copper pipe in Nitrous systems is that it flexes and eventually cracks...and leaks...

All the best Brett

UKKid35

I would have much preferred to use Nylon, but I couldn't work out how the fittings worked, and it would have cost me a fortune in comparison, nearly as much as the genuine part.

brianrheffron

The topic of materials for fuel lines has been covered before
but some facts arew worht repeating.
Don't use copper or stainless steel for fuel lines.
Both of these materials work harden which means that
the normal vibrations on a car cause them to embrittle
and eventually fail. The material of choice is Cunifer pipe.
This is a Copper/ Nickel/ Iron alloy which doesn't corrode and
doesn't work harden. It is more difficult to work than copper
but not beyond DIY bending and flaring. I've used it myself
for fuel and brake pipes with normal bending and flaring tools.
Coper is OK as a short term "work around" but in the long run
it is just not safe.

UKKid35

Brian, do you know if the original pipe is Kunifer? Presumably not since it corrodes. What about the replacement OEM pipe, is that Kunifer - if not why not? I reckon the copper pipe is probably the safest section of my fuel system relative to every other peice of fuel pipe. Finally, do you know the failure mode of copper pipe - catastrophic or weaping? Thanks

Brett928S2

Hi Paul

I have seen copper pipe (around a year old) on a Nitrous system "crack".. which was basically a longtitudinal line around a bend in the pipe, caused by vibration plus a 90 degree bend.

But Nitrous systems run at around 1000 psi where our fuel systems run at 40 to 50 psi...having said that I suspect it was the vibration that caused the crack (plus the bend) and not the pressure, although that would not have helped once the crack started...

Hope this helps...

All the best Brett

brianrheffron

Hi Paul.
Sorry, I don't know the failure mode of copper
or how long it would last but I do know that it is not
recommended for use on cars.
Having said that I have seen other folk use it on classics
probably because it is easy to buy, easy to form and does not corrode.
The original fuel hard lines were steel as are the replacement parts.

One of the reasons I went for a 928 was because they don't suffer
badly from corrosion but it beats me why Porsche went to the
trouble of an alloy and Galvanized steel body and non corroding
brake lines and then spoiled the job by making the fuel lines and
tank support spider out of mild steel. My fuel lines are weeping
and the tank spider is badly rusted out. I bought a stainless
steel tank spider from Paul Anderson which I will fit when I get
round to replacing the fuel hard lines.

I sometimes envy 928 owners based in places like Arizona
but at least in our cooler, damper and less sunny climate
the interior of my car has stayed in super condition.
I think that it's a lot cheaper and easier to replace the odd
rusted out item than it is to replace a bleached, dried out
interiorso maybe wi shouldn't complain about rust.

Maybach_Man

to work harden copper it needs to move, if the peice of fuel line is clamped to the underside of the car it is ridgid, unless there is a flexible hose at one end even then i will need to mve quite alot for the workhardening to take place. Obviously if the line were to, say, go between the body and the engine(constant movement and viabration) then i would agree