Results 1 to 16 of 16

Thread: Upgrading plastic coolant lines to braided lines?

  1. #1
    Join Date
    Nov 2016
    Location
    Oklahoma City, OK
    Posts
    309
    My Cars
    2000 BMW Z3 2.3

    Upgrading plastic coolant lines to braided lines?

    I'm hopefully going to do the full coolant system overhaul this winter, and I'm thinking about some of the inherent weaknesses in the system. The water pump is a well-known weak point (though to what extent is debated), and there is an easy upgrade for this. There is extensive talk about the weakness of the BMW plastics used in certain coolant pipes, but is there at all an upgrade for those?

    Stainless steel braided radiator hoses comes to mind, even though the hoses to the radiator are probably of least concern. Has anyone tried building a custom solution to replace the plastic pipes as well? What are some considerations that would prevent a person from switching all the lines, especially the plastic ones, to a system with braided flex lines and AN fittings?

    I can see how most would think it's not worth it, given the volume of available standard coolant parts for the engine, the lifespan of those parts, the relative ease of installation, and its priority compared to other repairs or upgrades. Still wondering if anyone has thought about or done this sort of thing.

  2. #2
    Join Date
    Feb 2012
    Location
    UK
    Posts
    1,847
    My Cars
    1998 Z3 1.9 5 speed
    The plastic parts are where the hoses interface with the engine block/head, not the hoses themselves.

  3. #3
    Join Date
    Nov 2016
    Location
    Oklahoma City, OK
    Posts
    309
    My Cars
    2000 BMW Z3 2.3
    Quote Originally Posted by BladeRunner919 View Post
    The plastic parts are where the hoses interface with the engine block/head, not the hoses themselves.
    So in order to eliminate the plastic being used there, you'd pretty much have to weld in some kind of metal connector or nipple to replace the block/head to plastic interface?

  4. #4
    Join Date
    Feb 2012
    Location
    UK
    Posts
    1,847
    My Cars
    1998 Z3 1.9 5 speed
    The plastic parts are fine for at least ten years. Definitely not worth the cost or effort effort of creating something bespoke.

  5. #5
    Join Date
    Aug 2015
    Location
    Denver, CO
    Posts
    3,444
    My Cars
    1999 Z3M, 1999 2.8 Coupe
    Quote Originally Posted by BladeRunner919 View Post
    The plastic parts are where the hoses interface with the engine block/head, not the hoses themselves.
    The coolant pipes interface with the engine block/head, not the hoses. The plastic fittings on the ends of the rubber hoses interface with the pipes. Those pipes are also entirely plastic and a real hoot to replace. The hoses also interface with the thermostat housing, heater core, etc. and are also plastic interfaces.
    Last edited by s8ilver; 11-08-2018 at 01:30 PM.
    Nathan in Denver

    1999 M Roadster, VFE V3 S/C, Randy Forbes Reinforced, Hardtop, H&R/Bilstein, Apex PS-7, Supersprint
    1999 Z3 2.8 Coupe, Headers, 3.46, Manual Swap, H&R/Koni, M Geometry/Brakes, M54B30 Manifold, Style 42

  6. #6
    Join Date
    Sep 2006
    Location
    Los Gatos CA
    Posts
    4,246
    My Cars
    1987 325is, e34, Z3, e39
    The flexible hoses aren't the problem, they are often in very good shape. The specific formulation of the PA 6/6 resin used in the rigid plastic pipes and hose end fittings is the problem.

    'Braided stainless' parts are often simply a decorative covering over a regular hose. They might keep an already-failed hose from bulging, or protect against abrasion. Or they can be a negative trapping grit where vibration causes it to grind away the hose.

    There is a good application for stainless braided coverings -- for custom applications where you can't do proper testing or design to avoid hose rubbing. But for stock replacement they are just decorative, not an improvement.
    Last edited by djb2; 11-08-2018 at 01:42 PM.

  7. #7
    Join Date
    Oct 2012
    Location
    Louisville, KY
    Posts
    4,503
    My Cars
    1997 BMW Z3 1.9L 5MT
    Quote Originally Posted by Schreier View Post
    ... Upgrading plastic coolant lines to braided lines?...
    There is no upgrade of the plastic coolant parts -- the pipe under the manifold of the 6 and 4 and the Y on the head of the 4. They are specific BMW parts, and are connectors to the heater valve.
    I have not seen pre-formed braided hoses from the radiator to the engine, though you might find such. However the rubber hoses are not a problem. The problem is the upper spigot on the plastic radiator where the hose connects. A braided hose is not going to help that.
    BMW MOA 696, BMW CCA 1405

  8. #8
    Join Date
    Jun 2011
    Location
    Springfield, Ohio, USA
    Posts
    1,233
    My Cars
    1998 Z3 Roadster
    I've actually never heard of a hose failing, only plastic parts: nipples, reservoirs, radiators, thermostat housings, and water pumps.

  9. #9
    Join Date
    Jun 2016
    Location
    Odessa, TX
    Posts
    880
    My Cars
    2000 BMW Z3 2.8 Roadster
    Don't forget the plastic pipes underneath the intake manifold (at least on the M54 and M52TU, I don't remember which other engines have similar), those are a hoot as well. I think for those, you could do custom designs for where they connect to the block, but you'd probably want to include parts that can flex and deal with thermal expansion? I'm not an engineer, and I don't remember a lot of detail about those pipes beyond how fun it was fishing the pipe nipples out of the holes in the block when they immediately separated during removal.

  10. #10
    Join Date
    Aug 2015
    Location
    Denver, CO
    Posts
    3,444
    My Cars
    1999 Z3M, 1999 2.8 Coupe
    Quote Originally Posted by LannVouivre View Post
    Don't forget the plastic pipes underneath the intake manifold (at least on the M54 and M52TU, I don't remember which other engines have similar), those are a hoot as well. I think for those, you could do custom designs for where they connect to the block, but you'd probably want to include parts that can flex and deal with thermal expansion? I'm not an engineer, and I don't remember a lot of detail about those pipes beyond how fun it was fishing the pipe nipples out of the holes in the block when they immediately separated during removal.
    Unfortunately I remember all too well, and I actually am an engineer. Not worth a custom design though; they last well over 100k miles. I replaced them at around 150k.

    20161220_160009.jpg20161220_132052.jpg

    If you are replacing the pipes on the M52TU, it's a great time to upgrade to an M54 manifold!
    Last edited by s8ilver; 11-12-2018 at 03:01 PM.
    Nathan in Denver

    1999 M Roadster, VFE V3 S/C, Randy Forbes Reinforced, Hardtop, H&R/Bilstein, Apex PS-7, Supersprint
    1999 Z3 2.8 Coupe, Headers, 3.46, Manual Swap, H&R/Koni, M Geometry/Brakes, M54B30 Manifold, Style 42

  11. #11
    Join Date
    Nov 2016
    Location
    Oklahoma City, OK
    Posts
    309
    My Cars
    2000 BMW Z3 2.3
    Quote Originally Posted by s8ilver View Post
    Unfortunately I remember all too well, and I actually am an engineer. Not worth a custom design though; they last well over 100k miles. I replaced them at around 150k.

    20161220_160009.jpg20161220_132052.jpg

    If you are replacing the pipes on the M52TU, it's a great time to upgrade to an M54 manifold!
    Wow! Glad they last 100K, but it's still annoying knowing that crappy plastic is under there. Thank you for sharing photos.

    I guess I'll concentrate on more pressing matters... like improving that manifold!

  12. #12
    Join Date
    Aug 2006
    Location
    Massachusetts
    Posts
    43
    My Cars
    e90 with Cobb, H&R, more
    I recently replaced the radiator overflow hose in my 335Xi because it had cracked/deteriorated from age. The last foot was ok where it connected to the overflow tank since that was thick, rubber hose with nylon reinforcement, but the rest of the hose had various issues. Unfortunately, the hose barb on the driver's side where the overflow hose attached to a plastic fitting broke off when I barely moved the hose. That hose barb is a molded part of the fitting, which also attaches to a 90 degree plastic fitting that comes out of the top, driver's side of the radiator, then at the other end it attaches to a reinforced hose that connects to the top of the engine by the oil filter. So the order of parts is:
    top of radiator (driver's side) -> 90 degree plastic elbow -> plastic fitting -> rubber hose -> engine block.

    The plastic fitting has the hose barb molded into the top of it and it broke right at the base. I've read/heard a lot about the plastic fittings deteriorating over time, as well as the plastic hoses where they attach to the fittings. I would strongly discourage anyone from replacing any hose or fitting unless absolutely necessary, and encourage them to do a DIY fix of some sort if at all possible. If you start taking apart pieces of the cooling system, I'd bet dollars to donuts you'll end up breaking more parts and opening up a can of worms.

    To fix my overflow pipe problem, I drilled and tapped the plastic fitting where the hose barb broke off with a 1/4" plumbing tap (the hole left by the hose barb was too small and needed a little widening). I then inserted a 2" piece of male/male brass plumbing into the hole, put a 90 degree brass female/male elbow on that, then put a piece of ~3 foot 1/2" ID reinforced fuel line (had it hanging around) onto the male side of the elbow and hose clamped it. I then put another 1.5" piece of brass male/male plumbing tube into the other end of the fuel line and hose clamped it, then put the other 3/4" of the male/male plumbing tube into the existing braided hose attached to the overflow tank. I trimmed the hose attached to the overflow tank by about 3/4" to get rid of the piece which had a piece of the cracked factory line inside of it. So, the order of parts is:
    plastic fitting, driver's side, with broken hose barb hole drilled out and tapped for 1/4" plumbing -> 1/4" ID 2" L male/male brass tube inserted into the tapped hole -> 90 degree female/male brass elbow -> 1/2" ID fuel line hose clamped over the male side of the elbow -> 1/4" ID 1.5" L male/male brass tube inserted into fuel line 3/4" and hose clamped -> other 3/4" of same brass tube inserted into existing braided hose coming from overflow tank and hose clamped.

    Make sure you are very careful tapping any plastic fitting. I'd highly recommend using a socket and 1/4" nut driver to hold the 1/4" plumbing tap rather than the standard jig in the tap kit that has the hole in the middle for the tap and two handles on it. It works WAY WAY better to use the nut driver so you can push directly down very hard while turning the tap. I put teflon plumbing tape on any joints where both pieces are threaded. If it's a joint with a hose clamp, no tape is needed. It's very important to use the 2" brass male/male tube to screw into the hole you tapped because it has about 3 extra turns of thread more than the 1.5" pieces, and you need those extra threads. Use zip ties to hold the hose in place. I ended up pointing the elbow towards the fender and then coming back down and towards the passenger side because the air intake plastic tube is in the way otherwise.

    I'll try and get a picture of this posted when I have a few minutes.
    Scott
    fast = good
    slow = bad
    See my old Porsche here...

  13. #13
    Join Date
    Jun 2016
    Location
    Odessa, TX
    Posts
    880
    My Cars
    2000 BMW Z3 2.8 Roadster
    If you need to replace one cooling system part, you probably need to replace all of them because they are all the same material and exposed to the same conditions. That should be the expectation. If a plastic part is starting to leak coolant, it's better to replace all of it ASAP than it is to risk a catastrophic failure, particularly since the plastic pipes underneath the intake manifold are so difficult to inspect. The good news is, once you replace the parts, they will probably last just as long as the ones that they're replacing (unless you go cheap).

  14. #14
    Join Date
    Aug 2006
    Location
    Massachusetts
    Posts
    43
    My Cars
    e90 with Cobb, H&R, more
    Quote Originally Posted by LannVouivre View Post
    If you need to replace one cooling system part, you probably need to replace all of them because they are all the same material and exposed to the same conditions. That should be the expectation. If a plastic part is starting to leak coolant, it's better to replace all of it ASAP than it is to risk a catastrophic failure, particularly since the plastic pipes underneath the intake manifold are so difficult to inspect. The good news is, once you replace the parts, they will probably last just as long as the ones that they're replacing (unless you go cheap).
    They aren't at all the same materials, nor are they exposed to the same conditions. There are both hard plastic fittings and hoses, two things that are entirely different materials. Then the hoses aren't all the same materials either. Then there's all of the metal parts that can be steel or aluminum. Beyond all of this, the rubber and plastic can interact with each other in ways the rubbers or plastic does NOT with metal parts.

    They're also exposed to vastly different conditions, starting with the fact that the closer to the engine things are, the greater the temperature fluctuations. I could go on with a lot more things such as parts right in the grille that are exposed to ambient, winter air that can be -40 degrees F all the way up to ambient, summer air temps over 100 degrees F depending on where you live.
    Scott
    fast = good
    slow = bad
    See my old Porsche here...

  15. #15
    Join Date
    May 2013
    Location
    USA
    Posts
    445
    My Cars
    2001 Z3 3.0/5 roadster
    Not to forget the effects of acidic engine oil coatings from leaking OFHG or VCG.

  16. #16
    Join Date
    Jan 2008
    Location
    Arida Zona
    Posts
    30,107
    My Cars
    z3
    Our cars dont have those barbs and stuff so almost that entire post about the 335i is irrelevant

    And yeah cooling systems should be replaced as a system. Ambient temps are largely irrelevant. The cooling system is under pressure with hot coolant flowing in it, THAT is what wears the components
    Last edited by BimmerBreaker; 11-15-2018 at 11:45 AM.

    Going into my TENTH YEAR of providing high quality reproduction BMW fabrics!

    PRICE CUT on ALL FABRICS
    Offering the best prices on the best quality reproduction fabrics!

Similar Threads

  1. 528i M52 Engine - Plastic Coolant Lines Under Intake Manifold
    By Bimmer Ese in forum 1996 - 2003 (E39)
    Replies: 26
    Last Post: 01-20-2022, 11:11 AM
  2. Clutch problems after braided line install
    By Green318is in forum 1991 - 1999 (E36)
    Replies: 11
    Last Post: 07-05-2006, 09:43 PM
  3. Braided Lines
    By markesq in forum Forced Induction
    Replies: 10
    Last Post: 03-16-2005, 06:04 PM
  4. Fitting for junction of hard fuel line and braided line.
    By Specter325 in forum Track, Auto-X & Drag Racing sponsored by Bimmerparts.com
    Replies: 3
    Last Post: 02-04-2005, 03:12 AM
  5. Upgrade plans .. need better jump off line damn manual
    By Truman325i in forum 1991 - 1999 (E36)
    Replies: 3
    Last Post: 09-13-2004, 02:57 AM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •