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 Post subject: Dreaded fuel lines need changing
PostPosted: Wed Nov 25, 2020 2:39 pm 
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My 944S had a couple of rubber pipes pieced in when I first acquired the car around 4 years ago and earlier this year the feed pipe sprung a leak just before I was taking the car to the Alps for some ice driving, luckily it failed before I left and not on the trip, I again bodged it with a rubber fuel pipe kit from Halfords.

So to current times and a week or so a go I could smell fuel but couldn't see a leak but checking the other day with the engine running I have fuel spraying up around the back end but too high to see where from just yet but its dripping off everything below it. So this seems like a good time to change the original pipes for new, I had a quote from OPC for pipes and it comes to silly money, there are 4 pipes now, I assume so that you don't need to drop the subframe?

I've been looking at copper fuel pipe and have measured my pipes at 8 and 10mm outside diameter and I already have a bending and flaring tool for the job and I've come across some lengths over 3m to make sure I have enough to do both supply and return which seems a reasonably priced but I am wondering what pitfalls I may come across doing this, I have read the threaded end are of a weird type but I am hoping that a hydraulics workshop may be able to do this for me? I've had a search for more info but I can't find an awful lot about DIYing these, has anyone used copper pipe before??


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 Post subject: Re: Dreaded fuel lines need changing
PostPosted: Wed Nov 25, 2020 6:08 pm 
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Hey infrasilver - pretty sure this has been covered either on here or on the PCGB forum, did you say you are getting fuel spraying at the rear? from the return line? I believe this goes up and over the rear axle to return to the tank and is quite awkward to get to with the axle in place...

Also think there is some information on this on rennlist, will see if I can find anything :)


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 Post subject: Re: Dreaded fuel lines need changing
PostPosted: Wed Nov 25, 2020 6:19 pm 
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Hi, there seems to be a fair bit of info but mostly from fitting genuine fuel lines and not many DIY jobs with copper pipe? I could probably just muddle through it but as this will have to be done outside on the drive I don't want to spent to much time under the car with trial and error in this weather so a tried and tested procedure would be helpful.


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 Post subject: Re: Dreaded fuel lines need changing
PostPosted: Wed Nov 25, 2020 7:00 pm 
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The only way to make your own is to remove what you have, to do this you will need to lower the offside of the rear beam by about 3-4 inches

This is quite possible on the drive as I have done 3 now

You need to mirror copy the pipes once removed, leaving a few mm extra at each end, then cut the fittings off your old lines and the fit then to the new lines and create the flares

I would not use copper, I would use kunifer pipe

It will take a bit of time, I can almost guarantee the brake lines in that area will also need replacing, once done you will never have to do it again

I really don’t like rubber hoses in exposed places under a car, I know modern cars have plastic lines, but they are always behind covers

You should be able to buy all you need from car builder solutions

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 Post subject: Re: Dreaded fuel lines need changing
PostPosted: Thu Nov 26, 2020 1:22 pm 
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Thanks Waylander,

It was kunifer I had in my mind, same as what I have for making brake pipes but I wrote copper!

Luckily the rubber sections are over the rear subframe and behind the wheel arch liner so are both out of the way but I think if I put more rubber in, there would be more of that than metal.

It was the end joints that worried me most as I couldn't think if they were fixed or they could be reused, if that is the case and I can reuse them I think I am sorted? I'm probably getting my wires crossed, now I think about it, the flex lines that go over the engine are the joints I need to worry about, I will probably have these replaced at the same time though.


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 Post subject: Re: Dreaded fuel lines need changing
PostPosted: Thu Nov 26, 2020 5:28 pm 
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I have seen some braided stainless covered for under the bonnet

As the ends of those are crimped on, if you get hold of a spare set, cut the pipe off by cutting the ferrules, then get a set made by Pirtek or similar

They will just crimp a new bit of pipe on for you, then get some of that nice silver heat shield wrap

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 Post subject: Re: Dreaded fuel lines need changing
PostPosted: Thu Nov 26, 2020 7:22 pm 
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I'm in the process of replacing mine the pressure line above the torsion bar snapped completely. I'm using braided PTFE all thought with metric fittings from Atec. Engine hose will have heat sheilding sleeve on. Id of hose is near enough same as the steel original feed, return will be the same, so slightly bigger. Tilting the beam is the only way to get the old hose and clamp out, done it didn't enjoy it.
After much searching Atec appear to be one of the few sources of metric fittings, a lot use AN plus an adapter in the States. I considered o/e pipes but they are a bit pricey and the flexies are NLA.
Original pipe mounts (plastic now) will be used with the rubber block trimmed for the wider braided hose. Feed will run from the filter via a 90 degree fitting to fuel rail and the return to a clamped fitting just before the existing union. It was available as a kit but I can't find the source anymore, it could have been Type911.

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 Post subject: Re: Dreaded fuel lines need changing
PostPosted: Thu Nov 26, 2020 9:17 pm 
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I'll just need to take a brave pill with regard to the weather and get on with this, I'll report back with any pitfalls I come across.


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 Post subject: Re: Dreaded fuel lines need changing
PostPosted: Thu Nov 26, 2020 10:33 pm 
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A few pointers....

I fully expect the rear beam rubber mount to be completely delaminated unless it’s been replaced

You will need to release the rear flexi out of its mount, and you may well need a jack to push the beam down out of its mounting point, oh and you will need to undo the bottom shock mount

The bolt is very very tight

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 Post subject: Re: Dreaded fuel lines need changing
PostPosted: Fri Nov 27, 2020 1:49 pm 
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https://youtu.be/tA3FwJPWszQ


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 Post subject: Re: Dreaded fuel lines need changing
PostPosted: Fri Nov 27, 2020 2:42 pm 
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well if you follow that video, I hope your fire insurance is up to date, the pipes are metal with crimped end for a reason, 5 Bar fuel pressure, the filter is not fitted with a cable tie from the factory, the bracket is missing, you can even see the mounting holes,

I personally cannot see the point of doing a half job.

for the effort of making half a pipe you might as well of made it all.....

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 Post subject: Re: Dreaded fuel lines need changing
PostPosted: Fri Nov 27, 2020 5:06 pm 
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I sort of except the point about cable ties, not entirely tho because although not original it was cable tied before and I suspect for a very long time. They are substantial cable ties which I think will last the distance but I may look into buying the original mounting bracket. The exposed pipes beneath the car floor are Kunifer hard lines (just as good as Porsche original) and even with fuel injection it’s quite acceptable to use twine fuel pipe clips providing there is a nipple at the end of the hard line to stop the flexible fuel pipe sliding off and one uses properly sized fuel hose.
I note you’ve done it three times on the drive. Very impressive. I don’t think I would have had the time or patience to lower the transaxle as well as do the fuel pipes. Sometimes doing enough is acceptable.
I think I’m happy with the safety aspect of it and it’s considerably better than it was before with the rubber fuel line inserts as repairs and rusty steel fuel pipe. I do carry a fire extinguisher but only because of the fires that have occurred due to the Porsche original fuel lines going over the top of the exhaust manifold, now remedied by the current arrangement.


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 Post subject: Re: Dreaded fuel lines need changing
PostPosted: Fri Nov 27, 2020 6:29 pm 
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When I had mine a previous owner had replaced the metal tank end with a long length of high pressure rubber. Both feed & return, all double clipped. I was a bit twitchy at first but in 38K & 4 + years it never gave any trouble.

One issue I did have was one of the tank straps rotted through. They are pretty expensive around £70 for one from memory but I made up a replacement using the ends rivetted to a length of aluminium. Worth check whilst you are under there as well is the exhaust shield & also the fuel pump cover which on mine was like a cobweb held together by rust.

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 Post subject: Re: Dreaded fuel lines need changing
PostPosted: Fri Nov 27, 2020 11:15 pm 
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Will keep an eye on this thread - I should be dropping my rear suspension at some point over the winter, plan is to refurb everything so I'm probably going to replace the brake and fuel lines even though I had them done by Promax a few years back.

Spotted the Sykes Pickavant bench mount flaring tool for about £150, is that the best one to go for?


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 Post subject: Re: Dreaded fuel lines need changing
PostPosted: Sat Nov 28, 2020 2:23 pm 
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I've ordered the required 8 and 10mm kunifer so I'll get on with this over the next week or so, had to order 7.5m of each so I will have a load left over at the end.

I did lose my tank shield a few months ago, had a terrible rattle from under the car and when I stopped I spotted the strap had snapped. I only noticed the cover was missing when I saw it lying in the road when I walked back to where I had driven.

Image

Welded the old ends onto a new metal strip I had cut and it all went back together nicely.

Image

Image

And the internal bracket had turned to dust so had to fab a new piece in and I cleaned up the whole thing.

Image

Image

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