Hey, Electrical Gurus! Need Some Wire Loom Advice.

69hurstolds

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Jan 2, 2006
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Piddling around under the hood of the 85 yesterday, I ran across the wire loom that was getting a bit stiff in areas and in fact, brittle and cracking. Obviously mostly due to age, but also some heat over the years.

Question for the electrical gurus: I'm assuming the gray stripe on the loom indicates it as nylon loom? Assuming electrical ID markings have remained the same over the years? Looking at new split loom, there's all sorts of material and UV/Heat "levels" from polyethelene on up for protective attribute. Since I'm going to go back to what is most like original, I found that the gray stripe means it's nylon and good for automotive underhood use and should hold up for the rest of my life. I do not know if the other ones under the hood are nylon, but the spread that covers the engine seems to be as it has the gray stripe. I cannot see any stripes on the looms not going over the valve covers, nor any stripes on the smaller looms. I'll look again closer, but it's just something I noticed I need to replace, if not for simple peace of mind. If so, I'm going nylon with all the loom near the engine or radiator. Polyethelene seems like it's the cheapest stuff on the market with nylon just a step above that.

The bigger issue is that most of the time, to get the "good stuff" you have to buy 2 miles of the junk. There's one place I've found that's "reasonable" with only needing to buy 50 feet of each size. Unless someone knows where to buy good stuff by the foot. I hate to go to an electrical shop and have them f** me over by selling me cheap crap for lots of $$.

elecDirect.com sells the stuff in more reasonable lengths (50 ft bags) if you don't need a truckload. Apparently, from what I can find out, it's a Techspan product, apparently made and sold predominately in Canada. So if it indeed is actually made in Canada, it's better than Chinesium. As long as it's not imported from the far east. At first blush, for $127.08 plus tax, and free shipping and I can get all 6 sizes in 50 foot lengths. Might not need all the different sizes though. I'll find them and measure to get a better feel for what I need.

Opinions?

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69hurstolds

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I failed to mention I personally HATE split loom running all over the engine compartment. But to make it right, it's got to look like 1985 under the hood.
 
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69hurstolds

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GM still sells wire loom conduit in 15' lengths. But for around 4 to 5 bucks per foot list price, I'm pretty sure I can find a suitable match elsewhere with the same performance specifications and appearance.
 

84 W40

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Dec 9, 2009
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You must have been reading my mind. There's one section of loom that I want to replace same situation your having. It's the loom that has wires for the M/C , Temp Sensor and what other wires are in that loom. The stripe color is not white but like a light green/blue. I do have other loom that does have a white stripe on it. Some of the loom out there is junk, too thin or soft you want the thick stuff. What we use at work is made by Panduit
 

69hurstolds

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Jan 2, 2006
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You must have been reading my mind. There's one section of loom that I want to replace same situation your having. It's the loom that has wires for the M/C , Temp Sensor and what other wires are in that loom. The stripe color is not white but like a light green/blue. I do have other loom that does have a white stripe on it. Some of the loom out there is junk, too thin or soft you want the thick stuff. What we use at work is made by Panduit
You can keep that Panduit. At 229.09 per 100' roll at Mouser.com, 1) I don't need THAT much, and 2) different sizes would run me a boatload of cash.

I think the blue stripe is high temperature and the red stripe is UV protection. I'll go out and look again.

My worst one is the 1" one going from the passenger side harness across the passenger valve cover and branching out to the rear and across the engine. Houses the test lead and TPS wiring. It has a gray stripe on it.

Like this (this is a GM parts loom):

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The techspan meets UL ratings and GM/Delphi specs, but isn't technically UL certified yet. Although it has been tested to meet those specs.

Here's the Panduit spec sheet. What's a bit concerning is even the nylon says it's rated for 230 deg F. That's 70 deg lower than the Techspan.

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84 W40

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Anything from Mouser your going to pay an arm and leg. My company buys direct from Panduit so prices will be lower. We stock other types of wire loom that are Mil spec but not the type you and I are looking for. That is interesting about the heat rating between both manufacturers. Need to ask one of engineers about that.
 

69hurstolds

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Yeah, it's weird.

I went out and looked at the 85 again. It appears MOST all the wiring looms have gray stripe that come close or over the engine. Even the tiny 1/4" one for the VIN 9 carb Idle Speed Solenoid. Also, the distributor wire loom going across the back of the firewall behind the booster has a gray stripe. However, the headlamp loom (1/2") doesn't have any markings. It goes along just inside driver fender and to the front of the car and across in front of the condensor.

Noted the positive battery cable loom coming off the battery has the gray stripe as well. Interestingly, I saw no other color striping.

Never thought to look at the 84 for some stupid reason.
 

oldsofb

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Maryland
Here's a spec I found on Waytek Wire:

Nylon Loom - Temp rating: -40°F (-40°C) to 257°F (125°C) (Up to 300 for short periods of time)

Polyethylene - Temp rating: -40°F (-40°C) to 200°F (93°C)

I had this site in my favorites from gathering supplies for my harness rebuild. Here's their loom (it looks like the smallest box is 50' though)
https://www.waytekwire.com/catalog/wire-coverings-and-protection/corrugated-loom

They have what looks like the correct style Tee Fittings, Loom End Fittings, and Loom Clips if that's needed too.
https://www.waytekwire.com/catalog/wire-coverings-and-protection/loom-fittings-and-clips

Hutch
 
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69hurstolds

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Jan 2, 2006
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Here's a spec I found on Waytek Wire:

Nylon Loom - Temp rating: -40°F (-40°C) to 257°F (125°C) (Up to 300 for short periods of time)

Polyethylene - Temp rating: -40°F (-40°C) to 200°F (93°C)

I had this site in my favorites from gathering supplies for my harness rebuild. Here's their loom (it looks like the smallest box is 50' though)
https://www.waytekwire.com/catalog/wire-coverings-and-protection/corrugated-loom

They have what looks like the correct style Tee Fittings, Loom End Fittings, and Loom Clips if that's needed too.
https://www.waytekwire.com/catalog/wire-coverings-and-protection/loom-fittings-and-clips

Hutch
That waytek site looks like they have a good assortment of loom, and they have a bunch of aptiv Tees and clips, which basically used to be Delphi/GM stuff anyway. Thanks for the lead. The prices aren't horrible either for some of their junk.

The Polyethylene looks ok to use on the headlamp harness, but around the engine, it's going to be nylon (gray stripe).

I checked my stash and lo and behold, I DO happen to have a couple of packages of the junk, the 5/16" and 1/2" stuff. I honestly didn't even realize I had them. Now I just gotta dig them out and see what's what.
 
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84 W40

G-Body Guru
Dec 9, 2009
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Well I spoke with an engineer 4 total about heat range between manufacturers, they were in the same room lucky me. It was like being on that Big Bang Theory show, what they said is Nylon loom can take more heat in a short period, the tests that they have done. They also said some manufacturers will give you those short period higher heat range and some will not. This is why they do there own tests. That's why they like using Panduit.
 

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