# "Dissing" Dissimiliar Metals **URL:** \ **Category:** Maintenance/Repairs\ **Created:** [August 10, 2013, 11:09am UTC](https://community.cartalk.com/t/dissing-dissimiliar-metals/80820 "2013-08-10T11:09:40Z")\ **Posts on this page:** 17\ **Page:** 1
**Author:** ![gudenteit](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/gudenteit/32/3004_2.png) [@gudenteit](https://community.cartalk.com/u/gudenteit)\ **Post date:** [August 10, 2013, 11:09am UTC](https://community.cartalk.com/t/dissing-dissimiliar-metals/80820/1 "2013-08-10T11:09:40Z")
I want to replace my rusting fuel and evap cannister steel lines with non rusting, copper refrigeration tubing. CUNI would be rather pricey, I’m told. But to avoid the dissimiliar metal oxidation that occurs with readily available steel flare nuts, I would have to try and find the brass flare fittings I’d need to splice into non rusted ends of tubings. Don’t know if this would be a difficult search or not, finding the 5/16" brass flare nuts I’d need, and the fuel filter fitting would be a very common 3/8" size, but the male flare nut threads would have to be metric. But I was wondering what chance I’d have to insulate copper tubing from steel flare fittings if I had to use steel flare nuts, using removeable grade thread lock between copper tubing and flare nut? ---
**Author:** ![meanjoe75fan](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/meanjoe75fan/32/552_2.png) [@meanjoe75fan](https://community.cartalk.com/u/meanjoe75fan)\ **Post date:** [August 10, 2013, 3:09pm UTC](https://community.cartalk.com/t/dissing-dissimiliar-metals/80820/2 "2013-08-10T15:09:34Z")
I wouldn’t trust copper to withstand the pressure and vibration of a modern, high-pressure EFI setup: it’s a much softer metal than steel. Other than having a ready supply, is there a reason you don’t want to replace with like metal? I’m all for “redneck repairs,” just not on fuel and brake lines. ---
**Author:** ![Barkydog](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/barkydog/32/2470_2.png) [@Barkydog](https://community.cartalk.com/u/Barkydog)\ **Post date:** [August 10, 2013, 5:06pm UTC](https://community.cartalk.com/t/dissing-dissimiliar-metals/80820/3 "2013-08-10T17:06:53Z")
Water lines use a dielectric coupling when joining dissimilar metals, I doubt it is worth the risk. Go with standard technology, imho. ---
**Author:** ![jtsanders](https://avatars.discourse-cdn.com/v4/letter/j/c2a13f/32.png) [@jtsanders](https://community.cartalk.com/u/jtsanders)\ **Post date:** [August 10, 2013, 6:23pm UTC](https://community.cartalk.com/t/dissing-dissimiliar-metals/80820/4 "2013-08-10T18:23:12Z")
You could use stainless steel instead of carbon steel. ---
**Author:** ![gudenteit](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/gudenteit/32/3004_2.png) [@gudenteit](https://community.cartalk.com/u/gudenteit)\ **Post date:** [August 10, 2013, 9:23pm UTC](https://community.cartalk.com/t/dissing-dissimiliar-metals/80820/5 "2013-08-10T21:23:36Z")
thanks for advice, i should plan to use stainless or CUNI even at high cost. ---
**Author:** ![texases](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/texases/32/862_2.png) [@texases](https://community.cartalk.com/u/texases)\ **Post date:** [August 10, 2013, 10:43pm UTC](https://community.cartalk.com/t/dissing-dissimiliar-metals/80820/6 "2013-08-10T22:43:22Z")
I’d just replace it with exactly stock materials. The corrosion that occurs with dissimilar metals can be quite rapid. I’d rather have to replace it again in a few years, and I might try protecting it with paint. How long did the original lines last? ---
**Author:** ![db4690](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/db4690/32/2583_2.png) [@db4690](https://community.cartalk.com/u/db4690)\ **Post date:** [August 10, 2013, 11:12pm UTC](https://community.cartalk.com/t/dissing-dissimiliar-metals/80820/7 "2013-08-10T23:12:51Z")
@gudenteit You’re messing with the fuel and emissions systems If the smog technician sees what you did, you will very likely fail the visual portion of the test These will be the reasons Emissions device removed/altered Emissions device shows evidence of tampering etc. Personally, I think you’re overthinking this Replace the evap components with the correct parts and crack open another beer . . . Afterwards, of course ---
**Author:** ![gudenteit](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/gudenteit/32/3004_2.png) [@gudenteit](https://community.cartalk.com/u/gudenteit)\ **Post date:** [August 11, 2013, 8:59am UTC](https://community.cartalk.com/t/dissing-dissimiliar-metals/80820/8 "2013-08-11T08:59:08Z")
texases, the fuel supply, return, and evap cannister purge line are original and have been in 13 years, it’s a 2000 Century ---
**Author:** ![gudenteit](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/gudenteit/32/3004_2.png) [@gudenteit](https://community.cartalk.com/u/gudenteit)\ **Post date:** [August 11, 2013, 8:59am UTC](https://community.cartalk.com/t/dissing-dissimiliar-metals/80820/9 "2013-08-11T08:59:38Z")
again, thanks for all replies ---
**Author:** ![kmccune](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/kmccune/32/1237_2.png) [@kmccune](https://community.cartalk.com/u/kmccune)\ **Post date:** [August 11, 2013, 3:54pm UTC](https://community.cartalk.com/t/dissing-dissimiliar-metals/80820/10 "2013-08-11T15:54:14Z")
Some of these auto repair stores sell a composite type of corrosion resistant high pressure metallic line now-Kevin ---
**Author:** ![texases](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/texases/32/862_2.png) [@texases](https://community.cartalk.com/u/texases)\ **Post date:** [August 11, 2013, 9:00pm UTC](https://community.cartalk.com/t/dissing-dissimiliar-metals/80820/11 "2013-08-11T21:00:13Z")
If the original lines lasted 13 years, I’d just replace them with stock materials. If you’re lucky, you’ll have to replace them in another 13 years. Odds are the car won’t last that long. ---
**Author:** ![gudenteit](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/gudenteit/32/3004_2.png) [@gudenteit](https://community.cartalk.com/u/gudenteit)\ **Post date:** [August 12, 2013, 2:32am UTC](https://community.cartalk.com/t/dissing-dissimiliar-metals/80820/12 "2013-08-12T02:32:44Z")
makes sense, texases, thanks. Kevin, are you referring to CUNI tubing? ---
**Author:** ![kmccune](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/kmccune/32/1237_2.png) [@kmccune](https://community.cartalk.com/u/kmccune)\ **Post date:** [August 12, 2013, 1:05pm UTC](https://community.cartalk.com/t/dissing-dissimiliar-metals/80820/13 "2013-08-12T13:05:18Z")
Dont know what they call it,just happened to see it at a parts store the other week-Kevin ---
**Author:** ![gudenteit](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/gudenteit/32/3004_2.png) [@gudenteit](https://community.cartalk.com/u/gudenteit)\ **Post date:** [August 13, 2013, 11:53pm UTC](https://community.cartalk.com/t/dissing-dissimiliar-metals/80820/14 "2013-08-13T23:53:17Z")
Kevin, CUNI=Copper Nickel ---
**Author:** ![Honda-Blackbird](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/honda-blackbird/32/3159_2.png) [@Honda-Blackbird](https://community.cartalk.com/u/Honda-Blackbird)\ **Post date:** [August 14, 2013, 6:35am UTC](https://community.cartalk.com/t/dissing-dissimiliar-metals/80820/15 "2013-08-14T06:35:05Z")
Why are you looking to over complicate a system that has been working near trouble free for decades on vehicles of all types. If you are dying for something to repair…take an icepick and poke some holes in your tires and then locate the holes and plug them up…sit back and enjoy the satisfaction of a job well done. ---
**Author:** ![George\_San\_Jose1](https://avatars.discourse-cdn.com/v4/letter/g/e5b9ba/32.png) [@George\_San\_Jose1](https://community.cartalk.com/u/George_San_Jose1)\ **Post date:** [August 14, 2013, 6:39am UTC](https://community.cartalk.com/t/dissing-dissimiliar-metals/80820/16 "2013-08-14T06:39:37Z")
One other consideration why copper may not be the ideal solution. Copper has a unique failure mode, to develop pinhole leaks. This is more likely to happen when running water in copper tubing probably, but one thing you definitely don’t want is a fine spray of gasoline in a hot engine compartment. ---
**Author:** ![kmccune](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/kmccune/32/1237_2.png) [@kmccune](https://community.cartalk.com/u/kmccune)\ **Post date:** [August 15, 2013, 1:03pm UTC](https://community.cartalk.com/t/dissing-dissimiliar-metals/80820/17 "2013-08-15T13:03:03Z")
Thanks,Gudenteit-Kevin