944 Fuel lines

[Dave Rolls]

I need to replace the fuellines due to rust.

Several internet forums mention using Nylon12 fuel lines (as used on later models, 911, 968 etc) in place of the solid metal lines.
(Has the advantage that the rear suspension beam doesn't have to be dropped)

Is this a good idea?

(The data sheet for the material seems ok,ie suitable for carrying fuel)

 

[ed325i]

I would also like to know this as my metal pipes have been replaced with rubber hose. Ed

 

[Paul 290T]

Dave, In 2002 my local indy changed the fuel lines on my 944 turbo for nylon. Cost was £200. I've had no trouble since. Modern plastic fuel tanks are made from nylon. Often the tanks are multilayer, with a PTFE insert, but the inner and outer shells are still nylon. Paul

 

[Dave Rolls]

Thanks, just the news I was waiting to hear! Cheers

 

[Hilux]

Their only disadvantage is heat and the need for more fixings if slung underneath. They are fine as long as fitted away from a heat source. Check PSI rating before buying.

 

[Dave Rolls]

Thanks for the input. Material comes with a data sheet that states: Temp range -30 to +70 C (occaisional use up to 120 C) Burst pressure is 1025 psi for 10mm supply line and 830psi for 8mm return line. Agree with you about extra support. Data sheet is from company called Colex, material is Estraflexible Altylon. They have a UK number, I will ring them on Monday to get their recommendation.

 

[chrisg]

Generally the consensus seems to be that the section of the fuel pipes that rusts is the part that goes up over the axle. When I redid my lines last winter I dropped the complete pair of lines off and took them to my Hydraulic specialist in High Wycombe. He inspected the pipes - with the exception of the corroded section they were fine - using the old corroded sections as a template he provided me with 4 x Stainless steel flexible sections (two for each end, over the axle and into the engine bay) which connected onto the fixed hard line with pressure couplings and olives. I asked about leakage and pressure etc - he smiled and explained that the fitments and pipes were designed for ~ 50bar, the fuel runs at a max of ~ 5bar....... Total cost for the pipes = £100 ! As an aside he had to do some brazing on one section to fit a new end for the pressure pipe - apparently the lines are pure steel but content an anti-corrosion agent. Spectrum Hoses, High Wycombe

 

[Dave Rolls]

Thanks, that sounds a good option. One problem with the plastic material is you have to buy a minimum 30m coil of 10mm and 30mm coil of 8mm tube which equals £100. Add some fittings/adaptors, say £50, then we have total £150. Your solution is cheaper. I'd heard that the OEM Porsche lines were ~£400. Out of interest i've just rung AFN Bournemouth. Their price is £287 for a fullset of lines (which includes the 2 flexibles to the engine).

 

[chrisg]

Dave Irrespective of which route you go down (new OPC lines, new SS flexi's etc) the biggest hassle and potential cost is dropping the axle. If you're at the stage that you have to change the lines due to corrosion, undoubtedly, unless it's been removed recently e.g. last 4yrs or so, the axle will be well wedged in and take some shifting from it's mounts - as I found ! By using the flexi hoses you should be able to get away without removing the axle, whilst retaining originality with the majority of the standard part. There does seem to be an approach with old 944's that only Porsche parts will do. Yes they're useful and important but neither old Porsches nor any other old car from the mid 80's uses fuel lines/ technology that can't be replicated very easily by an experience hydraulic hose fabricator

 

[Dave Rolls]

Chris, many good points to consider from everyone. The OEM parts come in 2 sections so you don't have to drop the back suspension. but your option sounds very tempting! I do not look forward to having to drop the back axle/suspension.

 

[jwindwood]

And there really isn't anything wrong with using rubber injection hose to replace damaged sections as long as they are properly clipped and supported. (And you remember that they don't last for ever! )

 

[George Elliott]

Dave, I replaced my fuel lines over the Beam with the correct fuel grade and pressure rated rubber hose in 8mm and 10mm, with two fuel line clips each on each end. It worked fine, it was easy to do relatively speaking, and did not add 20% to the cost of the car. The metal lines are old tech and very nice when new, but modern plastics are another possibility for some, - but others apply nuclear safety standards and MUST not chance anything on a high pressure [8|] fuel line. What I would also add though, is that IMO the two flexi lines from the OSF Arch into the engine bay are more dangerous by far. I had a real scare when I fitted a new down-pipe, following the reassembly of the intake manifold, fuel rail etc, I ran the engine with the bonnet open in the garage just to see everything was working. It started immediately, settled on tick over, and after 30 seconds watching the dash lights, I got out to a strong smell of fuel, quick glance under the bonnet, and I see a very fine mist of petrol over the rocker cover area, - so I dive to kill the ignition. The problem was the original (1989) flexi has a minute pin-hole 1 inch from the end, and the fuel is leaking in a fine mist, one spark......... I was really lucky as the front was in the air on stands. I do have an extinguisher, but Petrol would be a tough opponent. Good luck with whatever you do, but think about the flex's under the bonnet. They have destroyed many 944's. George 944t

 

[Mike_Pollock]

The front end flexies were / are the subject of a recall. My car had the recall but the engine was subsequently swapped and the pipe failed spraying the exhaust manifold with 1/4" wide jet of petrol!

 

[robdimond]

There is also the kit from RPM which I fitted over xmas. Its braided stainless steel and flexible so you don't have to drop the suspension. More expensive than most of the diy options discussed but it comes with all the fittings to go right from the filter to the fuel rail and also the 968 style plastic underbody clips. For me it made sense as I wanted to do it in one shot without faffing to get the right fittings. The hard part was threading the return line up past the fuel tank to the sender unit. Its a tight right angle.

 

[ed325i]

Have you link to RPM? Ed

 

[robdimond]

ORIGINAL: ed325i Have you link to RPM? Ed

http://www.rpmtechnik.co.uk/upgrades/engine/ They were very helpful on the phone, ask for a club discount.

 

[ed325i]

Thanks [] Ed

 

[os951]

Original fuel & brake lines are covered with some sort of polymer coating. I suppose the only place where they usually are in bad shape is near of right rear wheels, where lines goes over torsion bar carrier. I have tried to locate suitable replacement tubing (metal) with same greenish color coating to replace some brake lines. Need to fabricate a custom made tubing for Boxster/951 ABS combo system. We would not like to use plain copper or copper/metal material tube.

 

[grodob]

Has anyone used 10mm copper for the high pressure line? Seems a possible good route to go

 

[Hilux]

Yup, 8mm on my Golf Relatively cheap from e-bay with 2000psi burst pressure. Easy peasy BUT ensure you put a flare on the end when connecting to the flex pipes and use proper fuel pipe clips NOT jubilee clips as its (I believe a nominal 45psi pressure) You can use Kunifer or Copper kunifer is not much harder to bend. A flaring tool is cheap and allows you make yer own brake pipes too ( loverly jubbley )