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308 F.I. plastic lines to injectors - Weak design?

Discussion in 'Technical Q&A' started by dave80gtsi, Mar 31, 2004.

  1. dave80gtsi

    dave80gtsi Formula 3
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    Nov 3, 2003
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    Ohio
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    Dave Meredith
    Greetings to all - I am in the process of replacing all of the various fuel, coolant, and vacuum neoprene hoses on my 308, many of which are original and are in dire need of renewal.

    I have a question about the series of small diameter plastic tubes which lead from the fuel distributor to each of the various injectors. These bundled tubes on my car appear to be in good shape, in that they are still a bit flexible, and there are no obvious signs of problems with any of them. However, imagining a 'worst case scenario', if one of these small fuel lines were to fracture, the result could easily be the spraying of gasoline onto the hot header area, and somehow I think this could ruin my day if it were to occur.

    In general terms, is there any history of these small diameter lines frequently fracturing or splitting? Have these OEM tubes shown themselves to be pretty much bulletproof, or are they a ticking time bomb?

    Thanks for all of your opinions and thoughts - DM / Ohio
     
  2. Mark 328

    Mark 328 Formula Junior

    Nov 6, 2003
    510
    Orange, Ca
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    Mark Foley
    I have heard that replacements for these lines are unavailable.
    I have checked at several places and it appears that they are unavailable.
    In fact, I was told that the manuafacturer came into the stores and collected the remaining stock.
    Some cars used this type of tubing for vacuum lines.
    VW uses a braided stainless line for this purpose.
    I would be interested in hearing about repacements.

    Mark
     
  3. lou staller

    lou staller Formula Junior

    Dec 21, 2002
    371
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    Lou Staller
    I would also like to know if there is an alternative to plastic lines. Mine were so dry and brittle they actually cracked and broke apart. How about some type of braided line? Any ideas?
     
  4. dwil

    dwil Karting

    Nov 8, 2003
    108
    ozarks
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    Dave Wilson
    The old 911s use the cis system similar to the gtbi/si. I had bought the
    replacement nylon tubing in the correct metric size to replace the fi
    tubing on my 77 911s but haven't got around to it yet. The tubing
    and installation collars were very inexpensive from www.mcmaster.com.
    You could find more info on this by searching fellow fchatter Wayne
    Dempsey's Pelican parts website for info about "cis tubing" or "fi tubing"
    good luck!
     
  5. Verell

    Verell F1 Veteran
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    May 5, 2001
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    Verell Boaen
    The PelicanParts link you want is:
    http://forums.pelicanparts.com/showthread.php?s=&threadid=56968&highlight=Fuel+AND+line

    It reads:
     
  6. Birdman

    Birdman F1 Veteran

    Jun 20, 2003
    6,683
    North shore, MA
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    THE Birdman
    Anyone done this yet? I have a bad fuel line between the fuel distributor and injector (the plastic part) and need to replace it. Is the above info the best way to go?

    Thanks

    Birdman
     
  7. Birdman

    Birdman F1 Veteran

    Jun 20, 2003
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    This is the stuff for the Mondial/308 injectors (between the fuel distributor and injector hard lines) based on the measurements of my car:

    3mm ID x 5mm OD: stk number 50405K12@$0.26/ft by the ft.

    However that part number is discontinued. The new one is: 50405K24
     
  8. Verell

    Verell F1 Veteran
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    May 5, 2001
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    I've been poking around the CIS threads on the 911 forum. The 911 guys have found that that McMaster 6mm OD x 3mm ID line isn't rigid enough, it damps the oscillation of the little needle in the injectors, resulting in miss-firing & running lean!!!

    You need a 6mm x 2 mm line (2mm wall thickness) - See quote below.

    D&S Sales has the correct line, along with banjo fittings, etc:

    http://www.dssales.net/CIS.html

    Here are some relevant links on the 911 forum, including tools & tips on inserting the barbs into the CIS tubing:

    Pressing nylon fuel lines onto barb fittings
    http://forums.pelicanparts.com/showthread.php?t=184617

    CIS Fuel Lines http://forums.pelicanparts.com/showthread.php?t=338156

    Alternate CIS fuel injector hose/tubing?
    http://forums.pelicanparts.com/showthread.php?s=&threadid=185323

    CIS misfire
    http://forums.pelicanparts.com/showthread.php?s=&threadid=236328

    Bottom line from the preceding thread:

    Sorry to bring up a P-word car, but you gotta give credit where it's due...
     
  9. Birdman

    Birdman F1 Veteran

    Jun 20, 2003
    6,683
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    Hey Verell,
    Thanks for the links. I gave it a read. The only thing that is confusing me is that the Mondial fuel line is on my car 5mm OD and 3 mm ID, so it has 1 mm wall thickness. This is the same as the McMaster. Are the Porsche guys using the same line size? 6x2 is a mm larger on OD and a mm smaller on ID. I can't imagine how you would get it installed on the hard line without destroying something. The dssales website talks about needing to use a speacial reamer to make the end large enough to get on the hard line, but there is no link to that tool. Sounds sketchy....

    This all sounds logical, but why can't I just buy the CORRECT line...in the right rigidity to prevent pulsing? It must be available somewhere.

    Birdman
     
  10. Birdman

    Birdman F1 Veteran

    Jun 20, 2003
    6,683
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    In This thread they discuss Boxer fuel line and the proper size is listed as 6x2. I just checked my car again with a caliper. My car has 5x3 on the rear injectors and 6x3 on the front. So it looks like they replaced the rears at some point with the wrong thing. I think 6x3 is the right thing to find. It sounds like dssales is selling 6x2 and making people modify it to work.

    Birdman
     
  11. Ken

    Ken F1 World Champ

    Oct 19, 2001
    16,078
    Arlington Heights IL
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    Kenneth
    Back in the day (1970's) some fuel lines were plastic. My Lotus had all plastic fuel lines in fact. It is well known that modern fuel additives will make this plastic get brittle and crack over time. I have replaced all mine with modern stuff as well as changing the two plastic "T"s to brass. I don't know what Ferrari used in the 1980's but if it's the same kind of plastic I would be VERY worried about fuel leaks.

    Ken
     
  12. Verell

    Verell F1 Veteran
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    May 5, 2001
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    Just measured my Euro QV's injector lines, OD=6mm unfortunately there were no markings.

    IF 6mm OD, 3mm ID are the correct dimensions, then Newman's 1/4"(6.35mm) OD, 0.0625"(1.58mm) wall thickness -->0.125"(3.175mm) ID tubing is close enough, & has a thicker wall.

    The 50405K24 is Nylon 11, with a hardness of Shore D70. That's pretty hard(think plastic hard hat material) for a plastic, the harder the wall, the less it will pulse.

    Note that nylon tubing comes in several types, each with a range of hardness. (eg: Nylon 6(96A-112A/46D-81D (Hard)
    R 112), Nylon 11(57D | 70D ), & Nylon 12(50D | 63D )).


    I just searched McMaster & they' don't have 1/4" OD x 0.062 wall nylon line. But I did find 5437K111: 6mm OD x 3mm ID (1.5mm wall) line, Nylon 12 , 50D hardness & flame retardant. Rated for 175psi.

    MSC has a 65095481: 1/4" OD x 0.062 wall nylon line rated for 500psi, but they don't spec hardness tho.

    I suspect the D&S Sales reamer is just a simple taper reamer, probably matches the barb's profile except maybe 1mm undersize. It's the sort of thing that BOSCH would do. Certainly wouldn't be hard to make a tapered reamer out of 1/4" steel rod, hour or so with a lathe & mill. Nylon's soft enough so wouldn't need any hardening.
     
  13. Birdman

    Birdman F1 Veteran

    Jun 20, 2003
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    Hey Verell,
    Thanks for the help. I'm getting there. I just called Bel-metric right in MA and they have in stock the 5x3 stuff made by Cohline that is on the rear bank of my car. He is going to check the catalog to see if they make a 6x3. If so, we can order it, but he needs to order a big roll.

    Group buy!?

    Birdman
     
  14. Martin308GTB

    Martin308GTB F1 Rookie
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    Jan 22, 2003
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    Martin N.
    Hello from Germany,

    maybe you Bosch FI-owners are interested in contacting the classic car division, Bosch founded around three years ago.

    http://www.automotive-tradition.de/en/start/index.htm

    You can not only download several Bosch documents, spare parts lists, etc., but also send them your individual inquiries via e-Mail or a phone hotline.
    They are very helpful and I'm sure they will answer your questions regarding the FI fuel lines thoroughly. Maybe there's a procedure for replacement of the old clear plastic lines with the more reliable steel braided lines, VW, for example, used on their GTIs.

    I had a similar problem some time ago with the fuel injectors of a Bosch L-Jetronic and with the help of Bosch's Automotive Tradition department I quickly solved it.

    Best Regards

    Martin
     
  15. blkprlz

    blkprlz Formula 3

    Mar 24, 2007
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    Bruce
    I'm sure some of you are already on this, so rather than 50 guys contacting Bosch, I'll wait for your posted results........in the meantime,

    In the event that Bosch does not come thru w/replacement lines, count me in for some of that 5X3mm stuff (though my lines look in great condition but should stock up on it for the future). I'll get back to you w/a # after I do a take-off if this is the only route to take.
     
  16. RGigante

    RGigante F1 Rookie
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    Nov 1, 2006
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    Please count me in if you do get that 5X3mm stuff. My 328 is now 19 years old ....

    Thanks,
    Rui
     
  17. Birdman

    Birdman F1 Veteran

    Jun 20, 2003
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    Guys,
    The 5x3 is easily obtainable at a place near me. Unfortunately, Verell and I are pretty sure that while it clearly will get the job done, it is NOT the same spec as OEM, which I believe is 6x3. I am looking into finding the correct 6x3. Stand by.

    Birdman
     
  18. Birdman

    Birdman F1 Veteran

    Jun 20, 2003
    6,683
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    THE Birdman
    I searched that Bosch website and they list nothing for this fuel line. They do list most of the other CIS parts though. Might be a source for people looking for warm up regulators, etc.

    I have some tips from Brian Crall to follow up on. Dave Helms....you out there? Brian says you will know the part number and where to get this stuff.

    Birdman
     
  19. Verell

    Verell F1 Veteran
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    May 5, 2001
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    Just spoke with Larry Fletcher (CIS repair source) He said that the line to use is German polyamide(Nylon(tm)) line made by Cohline as Carmine mentioned in the other thread. Larry's pretty sure that the correct size is 5mm OD x 3 mm ID. That's definitely what he uses in his CIS test equipment, he read the dimension off of his roll of line while we were on the phone.

    BTW: "Polyamide: Polymer formed by the reaction of a diamine and a diacid. Nylons are commercial polyamides"

    Larry gave me a contact to call to double-check on. Will call tomorrow AM & post what I find.
     
  20. rizzo308

    rizzo308 Formula 3
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    Sep 12, 2004
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    riggio
    keep up the great work guys.............. forza......... i'll stay tuned
     
  21. Birdman

    Birdman F1 Veteran

    Jun 20, 2003
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    If I can use that and not have problems, that's great, because that stuff is easy to come by locally for us!! Maybe the OEM-sized 6mm/3mm stuff just isn't available anymore?

    Birdman
     
  22. Verell

    Verell F1 Veteran
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    My suspicion is that plastics technology has improved to the point where today's 5x3 meets the specs of the OEM 6mm OD tubing.

    BTW Birdman, did you actually go & cut one of your good 6mm lines to verify that it's 3mm ID?

    I did a reverse lookup on the phone # Larry gave me. It's NEWCO products in CA:
    http://www.newcoproducts.com/

    Browsing NEWCOs online catalog revealed that COHLINE makes a 6 mm x 3.15 mm line with 1.4 mm wall thickness, p/n 3011.3106-20

    I suspect that the -20 is the length as every p/n in the table ended in -20 & 20 meters is the std order size. Does say that 5 meter lines are available tho.

    I'll make that phone call tomorrow AM to check with NEWCO's Cohline guy.
     
  23. Birdman

    Birdman F1 Veteran

    Jun 20, 2003
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    I have to admit that I have not....I am hesitant to destroy any of the "good" lines until I know that I can fix them!
     
  24. Birdman

    Birdman F1 Veteran

    Jun 20, 2003
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    Hey Verell,
    OK, I have found the same page in the catalog. Let me e-mail the belmetric guy and see if he can get that stuff. I'm betting that is the stuff!!!

    I'll also bet that the 5x3 works just as well though.

    Jonathan
     
  25. dave80gtsi

    dave80gtsi Formula 3
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    Nov 3, 2003
    1,262
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    Glad to see this old thread that I started years ago is getting some new attention!

    How about we go in a slightly different direction - rather than new plastic tubing, what about a SS braided product?

    I've heard mention from time to time that this SS product exists, and can be used instead (a VW application??), but I've never seen any documentation, nor any B.T.D.T. testimonials from those who have upgraded away from the bare plastic tubing.

    Anyone?

    Cheers - DM
     

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