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Biodegradable Plastic Can't Take the Heat

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naperlou
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Inappropriate materials
naperlou   12/19/2013 9:17:33 AM
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Bill, I grew up with small British sports cars (MG, Austin Healey, Triumph).  We often had problems with hoses and seals (among many other problems).  It turns out that the British were still using natural rubber and that it did not hold up as well as synthetic rubber.

Turbineman
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Gold
Re: Inappropriate materials
Turbineman   12/19/2013 10:53:34 AM
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I have a 2003 Ford F350 with 24,500 miles (I don't drive it much).  Several times a year, I have to hunt down and repair/replace wires that were chewed through by rodents.  Talking to my mechanic who had just finished replacing the HP fuel pump, he explained that the insulation used by Ford in that era was regarded by the critters as strawberry short cake.  Now when it's not driven, it has several baited traps under the hood.  So far they like peanut butter better than the insulation.

bigpaws
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Re: Inappropriate materials
bigpaws   12/19/2013 1:51:13 PM
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Natural rubber!?  Sounds intuitively obvious that that would be a bad idea nowadays.  Hindisght and all being 20/20 so to speak.

 

Cheers

 

 

naperlou
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Re: Inappropriate materials
naperlou   12/19/2013 2:20:52 PM
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The main reason they used it was the colonial legacy.  They had plantations in southeast Asia from colonial times and still used them.  Henry Ford, in the late 1920s through the mid-1940s had rubber plantations in Brazil because the plantations in southeast Asia were closed. 

a.saji
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Re: Inappropriate materials
a.saji   12/19/2013 11:04:09 PM
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@naperlou: Yes that is the cycle. When there are new opportunities the existing ones do close. If not the market will be competitive. 

Pubudu
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Re: Inappropriate materials
Pubudu   12/25/2013 12:09:57 AM
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True a.saji, Sometimes this is the main issue when repairing the old vehicles or the antiques vehicles. 

Mydesign
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Re: Inappropriate materials
Mydesign   12/20/2013 12:24:09 AM
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"We often had problems with hoses and seals (among many other problems).  It turns out that the British were still using natural rubber and that it did not hold up as well as synthetic rubber."

Naperlou, I understood that heat bearing capacity of natural rubbers is very low. We have rubber plantation and during drying process, some of them get melted. By adding other components to make synthetic rubber can increase their thermal withstand levl.

Pubudu
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Platinum
Re: Inappropriate materials
Pubudu   12/24/2013 11:12:06 PM
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Bill this is a known issue in the history, I know some agents replace this parts for the all the cars that they have sold to the customers under there expenses. 

Mydesign
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Biodegradable Plastic
Mydesign   12/20/2013 12:20:21 AM
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"all cars made in Germany had to have biodegradable plastics for all plastic parts. It worked out fine everywhere else, except in the engine compartment where the heat caused the wiring insulation to break down."

Bill, why it's only happened to the plastic content in engine compartment? Am not an automobile engineer, but assume that engine is the most hottest part in a car. I my car I found that radiator and nearby areas are the hottest places.

bigpaws
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Iron
Re: Biodegradable Plastic
bigpaws   12/20/2013 1:23:57 PM
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Yup.  Youre intuition is correct.  All of the plastic will biodegrade at some point, but, it's accelerated in the engine compartment due to heat.  In the case of the Mercedes, they had one minor flash of forethought in that the engine harness is a sub-harness of the whole system - connected to the main harness via connectors. You still have to dig all throught the thing to replace it, but, at least there's no soldering needed.

 

Bill

 

Mydesign
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Re: Biodegradable Plastic
Mydesign   12/31/2013 2:48:14 AM
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"Youre intuition is correct.  All of the plastic will biodegrade at some point, but, it's accelerated in the engine compartment due to heat. "

Bigpaws, you are right. But plastics will have more durability in terms of degradation, when compare with other materials.

a.saji
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Re: Biodegradable Plastic
a.saji   12/31/2013 10:17:39 AM
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@MyDesign: How do you plan to make plastic re-usable in the future ?        

Mydesign
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Re: Biodegradable Plastic
Mydesign   1/2/2014 4:59:28 AM
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"How do you plan to make plastic re-usable in the future ?  "

Saji, that's a big question and most of the companies are still in R&D for the right answer.

Ann R. Thryft
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Re: Biodegradable Plastic
Ann R. Thryft   1/3/2014 1:04:19 PM
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How weird that biodegradable plastics would be used in under-hood applications. Plastics designed for those apps require a very different set of specs from those achievable with biodegradable materials, as DN has reported on several times.

zeeglen
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Gold
Re: Biodegradable Plastic
zeeglen   1/8/2014 10:45:07 PM
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This is what happens when politicians masquerade as design engineers.

jacknoble
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Re: Biodegradable Plastic
jacknoble   1/9/2014 12:44:47 PM
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The only wiring in the car that matches your symptoms would be the high voltage ignition wires.  Sounds to me like new plugs and spark plug wires would probably have fixed this vehicle.  It's really a shame so spend $2000 on a fix and then dump the car when a $200 fix would do, but I guess that's what keeps the American economy humming.

GDC
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Re: Biodegradable Plastic
GDC   1/9/2014 1:40:29 PM
The Mercedes of that era do not use spark plug wires in the sense that any sane engine does, at least the E series with the 3.2  L straight 6.   On the two I had, 1993 300E and 1994 E320 There were only 3 very short High tension leads.  There was one coil pack for every 2 cylinders.  The coilpack sat directly on top of one plug and a short lead attatched to the second one.  The primary side of each coil was hard wired into the wiring harness.  Mercedes used a wasted spark system in these engines.

The biodegradable insulation was a problem on the E series all the way back to late 1992.  I wound up rebuilding the wiring harnesses on both cars using less problematic insulation because I refused to pay for "new" harnesses with the a manufacturing date between 1993 and 1996 (the problem years).  The wire for the repair cost $35.00 for both cars, New Mercedes ECM boots were another $20.00 and the coil connecters were $11.00 and change.  In addition to the engine harness, the electronic throttle wiring had the same problem and will cause exactly the problems described in the OP.  I wound up rebuilding those as well.  The total for both cars was under $100 and one weekend of soldering beat the heck out of paying $1500 each to the dealership.

Because these were among the first cars with a digital CAN and multiple signals running over the same wires, any faults or noisy connections caused signifigant problems, usually leaving you on the side of the road.

In my case, the insulation problem didnt crop up until ~2008 or so and both cars failed close to each other.  My kids drove them through college and up until last year when the both bought more modern wheels.  Other than the issue with wiring, these cars were built like tanks.

Bryan Goss
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Gold
My 94 Toyota truck has been biodegrading since I bought it.
Bryan Goss   12/20/2013 11:57:36 AM
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My truck has been parked outside in the sun for most of it's 19 years in Los Angeles. It started degrading within a couple years of the time I bought it new, and at this point I have replaced most of the hard plastic parts in the cab at least once. The plastic just crumbles away. Thankfully it does not include the insulation of the wires, but does include door handles, door latches, trans linkage, window knobs, dash board, dome light, etc. Just more planned obsolescence as far as I can see.

bigpaws
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Iron
Re: My 94 Toyota truck has been biodegrading since I bought it.
bigpaws   12/20/2013 1:41:18 PM
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I wonder about the provenance of your plastic parts considering their behavior and the time-frame of the build.

 

Cheers

 

Bill

 

Bryan Goss
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Gold
Re: My 94 Toyota truck has been biodegrading since I bought it.
Bryan Goss   12/20/2013 2:01:39 PM
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Well for sure the parts that came with it when I bought it new were from Toyota, and all the replacement parts have been from the Toyota dealers. Granted they may be old stock at this point that was made back when the truck was made. I hope they keep them in a cold storage facility!

wbswenberg
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Re: My 94 Toyota truck has been biodegrading since I bought it.
wbswenberg   12/20/2013 11:14:45 PM
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A couple of years ago I finished breaking apart the interior of my '84 HiLux 4X4.  The arm rests and door panels are ok but the sides and back of the cab of hard molded plastic was removed.  I have almost as many miles on the second engine as the first 175K vs 265K.  

Had problems with a plastic keeper on my '95 K2500 for the clutch.  Turns out that it was failing cause the clutch was worn out.  Next time it will be a tow truck clutch as I haul a camper around 100% of the time.

I'm partly rebuilding the K2500 350cid engine.  Cylinders #6 & 8 have exhaust valve pitting in the seating area.  #6 had no compression.  #8 had 100 psi increasing to 145 with oil.  The right bank still had swirl marks from honing.  And #6 intake valve head was smaller than #8 guess the wrong part got into the assembly.  Made by monkeys I guess.  Lost my train of thought.  The valve stem seals broke off and the valve stem seals were hard.  Different kinds between intake and better sealing exhuast.  Interesting change.

 

Pubudu
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Re: My 94 Toyota truck has been biodegrading since I bought it.
Pubudu   12/25/2013 12:29:07 AM
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Bryan If so Toyota will not be able to export the vehicles to the Middle East countries due to heat............................

 

Bryan Goss
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Gold
Re: My 94 Toyota truck has been biodegrading since I bought it.
Bryan Goss   12/25/2013 10:47:49 AM
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Well based on what my Toyota has done, and a 99 that we bought and sold because it was showing signs of doing the same thing, it would seem they do not take climate into consideration when building cars, or they miss estimated the heat here in Southern California.

Pubudu
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Platinum
Re: My 94 Toyota truck has been biodegrading since I bought it.
Pubudu   12/25/2013 12:17:53 AM
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Bryan As I know most of the German vehicles do the country specialization where the veridical design for specifically for some country. Isn't it address those issues? 

engineerBob
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Iron
that explains it
engineerBob   12/20/2013 4:00:57 PM
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That explains all the gremlins in my Mercedes! 

Hilly-Billy-13
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Iron
Re: that explains it
Hilly-Billy-13   12/20/2013 5:04:31 PM
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the"biodegradable"plasticsaffectedalloftheeuropeancarsfromthe80'son,volvo240softhaterahavemoreissuesbecausethecoolingfanisdrivenbytheenginesothetempsbuildupaftertheengineshutsdown.vw'sbyusinganelectriccoolingfandon'thavetheissueasbad,butit'sstillpresent.howevertheelectrical&electronicsophisticationofmy1980vwrabbitwithi'sdieselengineissuchthatit'sanoneissue.
 
havingowned2englishsportscars,andworkedonothers,i'llskipthelucaselectricjokesfornow.
billhigdon

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