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Thread: Upgrading fuel lines engine bay M70

  1. #1
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    Upgrading fuel lines engine bay M70

    I am considering converting rubber hoses and clamps to stainless lines with twist on AN fittings.
    All of our engine bay hoses are prone to leaks and sometimes cause fires. I am tired of tightening up a bunch of clamps only to discover there is another fuel leak somewhere else!
    For example, on my 750 twin turbo I can smell a fuel leak under boost, most likely coming from drivers side firewall hoses that there is no way in the world i can possibly get to without either removing brake booster or intake manifolds.
    Has anyone eliminated rubber lines and clamps? Any input?
    I was thinking of doing this then adding stainless lines, any thoughts on this? :
    https://www.youtube.com/watch?v=l_Iw1kk_7jQ


    Note: this thread was copied from the 8 forum to the E32 forum, as it also refers to the M70 engine of the 750. shogun.
    Last edited by shogun; 02-27-2016 at 11:28 PM. Reason: see note, copied from 8 forum

  2. #2
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    Seems like a needless expense to me. I purchased about 3m of BMW fuel hose + a few pre-bent pieces and replaced every fuel line on the car. Should be good for another 15yrs or so now. Most of the hoses were original (25yrs old)! But the stainless lines do look nice.

  3. #3
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    I have changed fuel hoses on at least 7 or 8 M70 engines and most of them still experienced some sort of the leak down the line and needed clamp to be re tightened.
    My TT750 is another story, turbo is very close to those firewall fuel lines, so they experience too much thermal expansion and contraction.
    Are those BMW metal hard lines copper by any chance? Can they be easily cut and converted to AN type fitting?

  4. #4
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    What sort of clamp are you using? The poorly made but very available ones at most auto stores? Or the nice euro BMW/Benz style with the flared up edges? I know they are probably not euro style, but thats what I call em. They are nice, hold up well and dont cut the lines like the poorly made ones do.
    ______________________________
    1992 750iL

  5. #5
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    Somewhere must be a rubber (flexible) hose, the BMW engineers for sure thought about this. The engine is moving on the engine mounts clockwise and anti-clockwise a bit or more when engine mounts are bad, you need something in between the moving engine and the chassis.
    Same is with the coolant hoses from engine to the radiator and from engine to heater valves.
    Shogun tricks and tips for the E32 series are HERE!

  6. #6
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    use proper clamps and new hose and you won't have such problems....
    The SS route is a total nightmare, you'll see.....

  7. #7
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    AN fittings are great and I have been considering this as well, but stainless hose is such a pain in the ass. I am going to try to find quality hose clamps and give rubber hose another chance.
    Desecrator of all things Sacred

  8. #8
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    OP:If you do go SS, Contact 8Tech, He has a kit already to just mount up. No rubber only compares to Russell or Earl's HP Fuel line kits.

  9. #9
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    Somewhere over the yardarm I think you can get high pressure silicone fuel hoses. Might be a viable alternative. Silicone is very heat resistant, and also looks good. Pick your favorite color. The slotted worm screw style clamps are not the best for rubber hoses. Check out AutohausAZ for all the right stuff.

  10. #10
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    Used BMW clapms even the newer style ones with plastic with over tighten protection, eventually they all leak and need to be continually tightened especially true on FI
    Why negative sentiment on ss lines? Every single performance car, hot rod or exotic uses them. Why not use them on our cars, just trying to understand..
    Taking existing bmw hard lines and converting them to AN fitting is the only challenge I can see, why would bolting up SS lines with AN fittings to that be a nightmare?
    Even my cayenne TT has ss lines from factory, 80k miles later 0 fuel leaks.
    I checked phenix motorsport, did not see any ss lines, I will try contacting 8Tech through forum. Sounds like a great option!

  11. #11
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    OK, decided to give the rubber lines another try. Purchased gates Barricade high strength 5/16 fuel injection line 220psi. Swedish steel ABA fuel line clamps.
    Will attempt to access driver's side firewall lines via the wheel well.
    I remember coming across a thread where a 750 owner eliminated #16 junction in the pic below at the same time eliminating 4 connections and reducing leaking possibility down the road.
    Anyone else done this? Would I run into any unforeseen problems?

  12. #12
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    You need to use fuel injection hose clamps. If you insist on using worm clamps, you're going to have problems... There is a huge difference

  13. #13
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    Quote Originally Posted by cartoonz View Post
    You need to use fuel injection hose clamps. If you insist on using worm clamps, you're going to have problems... There is a huge difference
    Yep Aba stainless clamps are injection clamps. Not worm type.

  14. #14
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    Quote Originally Posted by dragon850 View Post
    Yep Aba stainless clamps are injection clamps. Not worm type.
    When you get them - I would like to see them so I can decide if I want to do the same.
    84 E31 cylinders - 72 Running

  15. #15
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    Quote Originally Posted by fursideup View Post
    When you get them - I would like to see them so I can decide if I want to do the same.
    I should be getting them by the end of the week.
    Here is the pic, these are 4 times more expensive than regular non stainless clamp sold in most parts stores. Will see if they are worth it.


    - - - Updated - - -

    Still would like to hear opinions on elimination of #16 fuel junction above.
    Shogun?
    If I remember correctly owner had to use heat/abrasive resistant sleeve on both hoses after eliminating that junction.

    - - - Updated - - -

    Answered my own question, dug up the old thread from shogun, so I think I will go the same route , eliminate the multi section and add sleeves to the hoses.
    Here is the old thread:
    http://www.bimmerboard.com/forums/posts/567886

  16. #16
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    Quick update, recieved clamps and abraisive/heat shield today. ABA Clamps are made in Sweeden, and are kick ass quality!
    Heat shield fits perfectly, will use it to eliminate the multi clamp junction at firewall.
    Pics of the clamps fitting over 13mm OD hose. Will update further when this is installed this weekend!


    ForumRunner_20160219_213542.png



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    ForumRunner_20160219_213634.png



    ForumRunner_20160219_213648.png

  17. #17
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    Good idea with the heat shield for the fuel hoses. Just checked with the part number I saw on your pic, spec:
    HEATSHIELD PRODUCTS (204012) 1/2" ID X 10' HOT ROD SLEEVE ROLL Price: US $28.01
    Hot Rod Sleeve is thermal sleeving capable of withstanding 1100 degree Fahrenheit continuous. This non-flammable sleeve has a special weave that allows it to expand and contract over fittings. In addition, it has that old school sleeve look with modern heat shield technology. Ideal for shielding fuel lines - helping to stop vapor lock, protect sensitive wire looms from close proximity heat, shield brake lines and hoses, and stop clutch cables from melting. This enables you to fit things into those tight places, and Heatshield Products know custom builds have lots of tight places. Available in 10 feet and 100 feet rolls. Continuous operating temperature of 1100 degree Fahrenheit, 2000 degree Fahrenheit intermittent, Capable of reducing up to 60 percent of radiant heat. Special weave that allows it to expand and contract over fittings, terminals and more, Helps to prevent vapor lock, protects wires from melting, shields oil and brake lines
    Manufacturer: Heatshield Products, Shipping Weight: 35, Product Dimensions: width: 2.70, length: 7.10, depth: 1.10

    There is even colored heat shield available
    http://www.amazon.com/Heatshield-Pro...4FPMY3251WGARM
    Last edited by shogun; 02-27-2016 at 11:35 PM.
    Shogun tricks and tips for the E32 series are HERE!

  18. #18
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    Here is the link for this heat shield for $20: https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
    I will post an update after this upgrade is done.

  19. #19
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    ...ordering 1, Great idea, Thanks!

  20. #20
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    I think this will especially benefit your FI 8s.
    Drivers side turbo on my 7 is so close to that fuel junction I can't imagine the heat it must be taking at boost! No wonder it keeps leaking, consistent extreme thermal expansion and contraction.
    Planning to knock this out tomorrow.
    Alex840 is coming over for some rebuilt DK motors, maybe he'll give me a hand with this

    Quote Originally Posted by 8eights View Post
    ...ordering 1, Great idea, Thanks!

  21. #21
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    Is the hose 8mm inside diameter and 13mm outside diameter?
    what length of hose do I need and how many clamps?
    i am replacing from the tank to the motor.
    time to replace both pumps and filters and hoses.

  22. #22
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    Yes, you got it. Id 8mm od 13mm.
    I have not done the upgrade yet, hoping to knock it out this weekend and update the thread. BTW only use hi pressure fi hose. I just received gates barricade 225psi hose, looks like a quality very tough hose!

  23. #23
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    Thanks got the reply
    I wish to order the Aba clamps but don't now how many to order???

  24. #24
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    +1 just ordered hose, clamps 10 pack and heat shield from amazon $68 doing this with the rocker cover gaskets etc.etc.... $$$$$$$
    "91 850i diamantschwarz"

  25. #25
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    Just finished upgrading fuel lines with spectacular results.
    Replaced 3 multi junction hose sections, 2 at drivers firewall and 1 at passengers.
    Used 225 PSI Gates Barricade FI hose 5/16, ABA stainless steel clamps and heat shield.
    First you have to remove the wheel and plastic cover at the driver's side wheel well.
    Attachment 565057

    7 anchors securing fuel lines to the frame have to be dropped.
    Attachment 565058

    Undo clamps from the top of the engine, mark hoses and metal lines going to fuel rail so you can identify which fuel pump goes to what bank.
    Attachment 565059

    Remove one line at a time so you can also mark the lines at the wheel well to match the lines at the top of the engine.
    It took some time to pull the line out through the wheel well mainly due to the clamp hitting the frame, I had to actually make the opening slightly larger, the metal is thin.
    Here is the first junction I pulled out, then pulled the second one.
    Attachment 565060Attachment 565061
    Attached Images Attached Images

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