Fuel system question

[Soulbrotha]

The fuel hard lines are rusted real bad. Real OEM will give me a part number but no size for the diameter of the inside or outside of the fuel hard line. Ive read a lot about how easy it is to replace but size of tubing is never mentioned. Also read that the flow and return lines are different size.. Came to the conclusion that 1/4 inch tubing MIGHT work but i cant pull the trigger on it yet. Could there be bad side affects if there truly is different sizing and i just roll with one size throughout

[Side Quest]
I threw in a picture of a break line intersection. Anyone know the size for this?

[varg]

Fuel hardline is 8mm OD, 5/16" will work if you can't get metric hardline but might have to 5/16" hose with it, the 8mm hose might fit a little loose. The difference is only 0.062mm though. The return and supply are the same size, the small one is the evap line. Brake lines are 3/16" bubble flare, M10x1 thread on the fittings.

[crash n' burn]

I'm going to be that guy and ask why you just don't order new lines, they're cheap and pre-bent. took me 15 minutes to replace them with new clips while i was doing the filter.

[Soulbrotha]

Fuel hardline is 8mm OD, 5/16" will work if you can't get metric hardline but might have to 5/16" hose with it, the 8mm hose might fit a little loose. The difference is only 0.062mm though. The return and supply are the same size, the small one is the evap line. Brake lines are 3/16" bubble flare, M10x1 thread on the fittings.

thank you sir

I'm going to be that guy and ask why you just don't order new lines, they're cheap and pre-bent. took me 15 minutes to replace them with new clips while i was doing the filter.

I did the google thing and couldn't find any hard lines. When did you replace yours? read that pre bent hard lines are scarce these days.

[rmdashrf]

My new lines weren't pre-bent.

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[dnguyen1963]

Useful link...

http://www.rtsauto.com/fuel-brake-line-fabrication/

[digger]

depending which ones youre after and if youre an early or late car these are prebent

https://www.ecstuning.com/b-genuine-bmw-parts/8-return-pipe/16121179682/

https://www.ecstuning.com/b-genuine-bmw-parts/8-inlet-pipe/16121179681/

[101]

I replaced the metal lines on my IX two years ago. The fuel lines came pre-bent from BMW. The brake lines do not.

I used "cunifer" metal lines for the brakes. Much easier to fabricate and bend than the BMW steel brake lines, and they will not rust - ever.