Fuel Pipe - what is best replacement material?

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Stew-Em
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Hi,
With a leak in fuel pipe have opted to replace entire length(s) in my '87 lwb 300D. What is the best replacement material? Possible 8mm options include (and approximate prices as found from quick web search):
Copper (£2-£3/metre fully annealed coil)
Nitrile (internally braided, £2-£3/metre)
Rubber (black cotton overbraid, £3.50)
Mercedes own £4.80/metre (material?)

Any suggestions where to buy very gratefully received! Any other advice also welcome - is 6m enough or play safe with 7m?
Thanks
Stewart

Pistonhead
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Re: Fuel Pipe - what is best replacement material?

Hello Stewart,

If you are talking of replacing the entire system, then it is fuel pipe you want for the most of the circuit, rather than fuel hose.

The fuel pipe can be bought at any good motor factor.  Is the leak on the pipe or fuel hose?

Pipe leaks occur through pitting due to corrosion and usually checked at MOT tests.

Cheers,

Stew-Em
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Re: Fuel Pipe - what is best replacement material?

Rakesh,
Thanks once again for the rapid response. Leak is 'somewhere' on pipe - have not been able to locate. Possible to repair if found but consider replacing all to have 'peace of mind'. Drips appear along chassis where it drops from the front (between gearbox and transfer box). Symptons are however;
When parked:
1. Point car downhill - leaks quicker
2. Point uphill - little leakage but G then difficult to start (air in system suspected problem)
When driving:
Stop at uphill junction G liable to stall.
Reverse (and stop) G liable to stall.

Would you suggest copper piping as suitable?
Cheers,
Stewart

Stew-Em
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Re: Fuel Pipe - what is best replacement material?

Re leak location - number of mechanics have also failed to identify leak location. Originally difficult as also leak from hydraulic pipe in same area (now fixed - feeding rear diff lock). Have tried on many occasions but...?!?

mgrays
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Re: Fuel Pipe - what is best replacement material?

Leak location.. hot pressure washer the whole area and then let it dry.. the oily stain of diesel will become apparent.

Best material is actually Cupro-nickel .. but copper will do. Copper can work harden if vibrating/moving so is hence is not as perfect. Cupro-nickel has higher burst pressure (for brake pipes especially) but is about twice as hard as copper to bend., plus does not work harden with vibrations but more expensive and hard to bend so mechanics do not like it. It resist corrosion as well as Copper. Why it is not law to fit them to fuel/brake lines along with SS braided flexi lines? Cost per vehicle about £30 extra and would last a lifetime.. but owners sell in 3 years so they don't care about this safety critical item.

http://www.google.co.uk/#q=cupro+nickel+brake+pipe&hl=en&prmd=imvns&source=univ&tbm=shop&tbo=u&sa=X&ei=AWfHT9rEMsaX8gPklK3bDQ&sqi=2&ved=0CJ4BEK0E&bav=on.2,or.r_gc.r_pw.r_qf.,cf.osb&fp=a77b59150c6a0b9a&biw=1280&bih=872&safe=active

Pistonhead
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Re: Fuel Pipe - what is best replacement material?

Hello Stewart,

mgray's thread, refers to the copper pipe as prefrence, but the brake pipe's internal diameter is not large enough to accommodate the flow of fuel you need; should you opt copper pipe for your installation, you could find at high revs, symptoms of fuel starvation.  

A full reel of copper tubing is some 30m, which you do not need.  The pipe length you need, runs from approximately,  half of the rear wheel arch, along the top of the near-side chassis frame and coming up to the half of engine length, I, estimate, no more than 2.5m.  These can be bought from the motor factor or parts accessory shop by the meter.

Alternative repair would be, once, the leak area has been detected, cut a short effected part out and insert that cut out section, with a rubber fuel hose.

Cheers,

mjkirk
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Re: Fuel Pipe - what is best replacement material?

I always use semi rigid plastic tubing, readily available from anyone supplying lorry spares, or, for instance, my local hydraulic hose man keeps it. This is air pipe on lorries etc, and is the same as the stuff mercedes use between the fuel filter housing and the injector pump. Won't rust or crack, and it looks right. You can warm it up with hot water to push it onto fittings and to bend it, or connect to it with short lengths of quality fuel hose and clips.

mgrays
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Re: Fuel Pipe - what is best replacement material?

Cupro-Nickel is available in all the same sizes as copper; it is preferable to copper because of work hardening issues. TBH you are unlikely to get work hardening so it is "gold plating" unless you want to go 200-400k miles more without looking at it. Yes you do need to buy a 25'/7.5m reel.. but it will do about 2 cars for about the same cost as buying enough per meter to do 1 car; being Scottish I always go for more for less even if it does mean storing it for 10 years..

Here is a "cupro nickel pipe" search instead of a "cupro nickel brake pipe"
http://www.google.co.uk/#hl=en&safe=active&tbm=shop&sclient=psy-ab&q=cupro+nickel+pipe&oq=cupro+nickel+pipe&aq=f&aqi=&aql=&gs_l=serp.3...123873.123873.0.124561.1.1.0.0.0.0.172.172.0j1.1.0...0.0.QewqLBxJZ-I&pbx=1&bav=on.2,or.r_gc.r_pw.r_qf.,cf.osb&fp=69f36ca917fe470b&biw=1280&bih=872

Not sure on sizes but 10mm for supply fuel line and about 6mm for return is a guess but please measure first..

Cupro-nickel 10mm x 7.5m is £36 delivered
Cupro-nickel 6mm x 7.5m is £21 delivered
Copper 10mm x 10m is £20 delivered or £3/metre
Copper 6mm x 10m about £17 or £2/metre

Anyway.. not a lot in it but Copper will do just fine for next 70,000 miles.. and you only need to buy about 4-5m of each (use a bit of string to measure insitu before you buy..)

Plastic works it seems and is a whole lot easier to work with; fitting is the pain in this case but is more a "bronze plating" solution.. fit for purpose compared to the "silver plating" copper solution. Making it pretty with copper will be hard, with cupro-nickel will be really hard as there is not much room for fingers above the chassis. Saying that I have a "repair" length of rubber in my supply line from the previous owner so I should definitely not be doing any preaching! :(

Stew-Em
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Re: Fuel Pipe - what is best replacement material?

Thanks all for advice. Having done my research I have opted to purchase some 8mm Kunifer (cupro-nickel, as specified for brake pipes). Measured my pipes, both 8mm outside diameter (OD) - the kunifer has wall thickness of 0.071mm, thinner I suspect than the originals and copper at typically 1mm. In the past I have owned cars and regretted shorter term solutions (usually exhausts by not choosing stainless steel) - Ideally I hope to keep this car long term (as long as I don't need it for a daily commute and other things permitting) so for the sake of an extra £20 for 7.5 metres not to concerned - never know when I might need some for the brakes either! Also means can make mistakes (or should I say 'amendments'?) when bending to fit as no fear of work hardening.

As a quick extra - what clips are available to fix the pipes to the chassis? How is this best done, chassis still has grey paint underneath grease and grime and would rather not rub down for welding...?

Thanks, Stewart

stig
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Re: Fuel Pipe - what is best replacement material?

 Hi Stewart, you should be able to clip the pipes back into their original mountings, you just need to pry open the steel 'ovals' and remove the rubber that contains all the pipes, then replace in reverse. Beers Scott