Notices
Mercedes Tech Talk Discuss general technical questions and issues about your Mercedes-Benz. Moderated by a certified MB Tech.
Sponsored by:
Sponsored by:

Wiring harness repair

Thread Tools
 
Search this Thread
 
Rate Thread
 
Old Sep 15, 2006 | 03:58 AM
  #1  
everlyne's Avatar
Thread Starter
Newbie
 
Joined: Dec 2004
Posts: 5
Likes: 0
Wiring harness repair

My 1992 W140 wiring harness insulation has gone brittle. I would like to replace the wire. The engine compartment is pretty hot. What sort of wire should i used? I believe i need wire which is resistance to heat, chemical, oil, etc. Please advise what type of wire should i used.
Thanks in advance guys. Appreciate your help.
Reply
Old Sep 15, 2006 | 09:00 AM
  #2  
vettdvr's Avatar
MBWorld Fanatic!
 
Joined: Mar 2006
Posts: 3,254
Likes: 15
From: Louisiana
03 E500 and Corvette
Originally Posted by everlyne
My 1992 W140 wiring harness insulation has gone brittle. I would like to replace the wire. The engine compartment is pretty hot. What sort of wire should i used? I believe i need wire which is resistance to heat, chemical, oil, etc. Please advise what type of wire should i used.
Thanks in advance guys. Appreciate your help.

Off the cuff I can't answer, but I have been experienced in management decisions on wire for hot papermachine applications (210 F+) and we used special covered wires. Unfortunately I don't remember which ones. I'll check to see if I can find anything. I would consider off the shelf wire from an (electronic supply house) not electrical contractor construction. They might be able to give you the temp ratings on the insulation which is what you really need. Give them they might be able to give direct local help.

Also try http://nepp.nasa.gov/npsl/Wire/insulation_guide.htm For wire specs. This should help also Jim

Last edited by vettdvr; Sep 15, 2006 at 09:52 AM.
Reply
Old Sep 15, 2006 | 08:51 PM
  #3  
csumt76's Avatar
Super Member
 
Joined: May 2004
Posts: 755
Likes: 2
From: USA
LS7 powered Corvette
Buy a new harness.. I wouldn't reccomend repairing it solely because of resale value. I would never buy a car that had a harness repaired by the owner. Just my $.02.
Reply
Old Sep 16, 2006 | 09:05 AM
  #4  
vettdvr's Avatar
MBWorld Fanatic!
 
Joined: Mar 2006
Posts: 3,254
Likes: 15
From: Louisiana
03 E500 and Corvette
Originally Posted by [MB]CRS
Buy a new harness.. I wouldn't reccomend repairing it solely because of resale value. I would never buy a car that had a harness repaired by the owner. Just my $.02.
I can agree on this to a point.

I have tried to buy a new harness in the past from the dealer to find it was not available and only option to repair, rebuild or buy from junk car. My preference has always been to build a new harness given connectors available. When connectors aren't available I buy new connectors for that application (weather sealed) when possible. I do agree that a chopped hacked harness is a good place for a fire and would hurt resale of a car, but given the repair is done properly a repaired harness should work as well as a new one. Jim
Reply
Old Sep 17, 2006 | 12:58 AM
  #5  
csumt76's Avatar
Super Member
 
Joined: May 2004
Posts: 755
Likes: 2
From: USA
LS7 powered Corvette
Originally Posted by vettdvr
I can agree on this to a point.

I have tried to buy a new harness in the past from the dealer to find it was not available and only option to repair, rebuild or buy from junk car. My preference has always been to build a new harness given connectors available. When connectors aren't available I buy new connectors for that application (weather sealed) when possible. I do agree that a chopped hacked harness is a good place for a fire and would hurt resale of a car, but given the repair is done properly a repaired harness should work as well as a new one. Jim
Yes, I agree with that. The harness for a 92 should be easily available, although it may not be cheap.
Reply
Old Sep 17, 2006 | 04:31 AM
  #6  
Moviela's Avatar
MBWorld Fanatic!
20 Year Member
Photogenic
Photoriffic
 
Joined: Jan 2005
Posts: 2,848
Likes: 15
From: Orange County
2005 C Wagon (No snickering please!)
It might be more economical to replace the harness from the factory, if the insulation is failing all over, even given the initial high price. If just a single wire or breakout has failed, and the balance of the loom is fresh and supple, I would use a silver plated copper wire with teflon insulation. Then you will need connector housings, terminals, and a very expensive crimper to terminate the wires correctly. I have used this wire to harness vintage Porsche cars.

http://www.weicowire.com/specpage.asp?nGroupID=150
Reply
Old Sep 22, 2006 | 08:53 PM
  #7  
MBTECH2003's Avatar
Member
 
Joined: Jun 2005
Posts: 75
Likes: 1
From: Chicago, IL
2000 ML 320, 2003 CBR600F4i, 99 Eclipse GSX
Definitely get the harness. Unless you have all new terminals for all of the connectors you will never get all the corrosion out of the harness and it will fail anyways. And yes the dealer's have these harnesses... in face our dealer stocks them for all of those cars due to the frequency of replacement.
Reply
Old Sep 22, 2006 | 10:33 PM
  #8  
CalifSLK's Avatar
Almost a Member!
 
Joined: Dec 2005
Posts: 62
Likes: 0
From: San Jose
SLK 350
Originally Posted by everlyne
My 1992 W140 wiring harness insulation has gone brittle. I would like to replace the wire. The engine compartment is pretty hot. What sort of wire should i used? I believe i need wire which is resistance to heat, chemical, oil, etc. Please advise what type of wire should i used.
Thanks in advance guys. Appreciate your help.
Except in the door jam, I have really never seen a wire failure. Even in a door jam, I have only seen the passenger side fail. This is because it was seldom used and the insulation took a set, then it cracked when someone got in the passenger side. The only real moving points on an engine wiring harness is where the bundle goes from the car body to the engine. These points are usually carefully designed for longevity. The most prong to breakage is the large gauge wires. Wires used in moving assemblies (e.g. floppy disk drive read/write heads) have very fine individual strand inside and they can work millions of cycles.

Even owning a diesel for 20 years, where the engine vibrated much worst than a gas car, no wire breakage on that engine in the time that I had it.

Insulation may look bad, but that doesn't mean the wire strands inside will break. Just leave it.
Reply
MB World Stories

The Best of Mercedes & AMG

story-0

7 Craziest Things AMG Gas Ever Built

 Verdad Gallardo
story-1

New Electric Mercedes-AMG GT 4-Door Coupe Unveiled: 10 Things You Need to Know

 Verdad Gallardo
story-2

6 Mercedes Models That Did NOT Age Well (But Are Somehow Still Cool)

 Verdad Gallardo
story-3

Manual Mercedes? 6 Times Sindelfingen Let Drivers Have All The Fun

 Verdad Gallardo
story-4

Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren

 Verdad Gallardo
story-5

8 Classic Boxy Mercedes Designs That Have Aged Like Fine Wine

 Verdad Gallardo
story-6

Flawlessly Restored Mercedes 190E Evo II Heads to Auction

 Verdad Gallardo
story-7

Electric Mercedes C-Class Unveiled: 11 Things You Need to Know

 Verdad Gallardo
story-8

Mercedes EQS Gets A Major Update: Everything You Need to Know

 Verdad Gallardo
story-9

5 Underrated Mercedes-Benz Models That Don't Get the Love They Deserve

 Verdad Gallardo

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 


You have already rated this thread Rating: Thread Rating: 1 votes, 5.00 average.


All times are GMT -4. The time now is 08:00 PM.

story-0
7 Craziest Things AMG Gas Ever Built

Slideshow: Sometimes AMG builds fast sedans. Other times, it builds twin-turbo V12 land missiles and six-wheeled off-road monsters.

By Verdad Gallardo | 2026-05-26 17:59:58


VIEW MORE
story-1
New Electric Mercedes-AMG GT 4-Door Coupe Unveiled: 10 Things You Need to Know

Slideshow: Mercedes-AMG's new electric GT 4-Door Coupe trades combustion for software, synthetic noise, and more than 1,100 horsepower.

By Verdad Gallardo | 2026-05-20 20:08:15


VIEW MORE
story-2
6 Mercedes Models That Did NOT Age Well (But Are Somehow Still Cool)

Slideshow: Not every Mercedes design becomes timeless, some feel stuck in the era they came from.

By Verdad Gallardo | 2026-05-12 18:09:07


VIEW MORE
story-3
Manual Mercedes? 6 Times Sindelfingen Let Drivers Have All The Fun

Slideshow: Yes, Mercedes built manual cars, and some of them are far more interesting than you'd expect.

By Verdad Gallardo | 2026-05-02 12:36:58


VIEW MORE
story-4
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren

Slideshow: A one-of-one U.S.-spec Mercedes-Benz SLR McLaren Roadster became even rarer after a factory-backed transformation at McLaren's headquarters.

By Verdad Gallardo | 2026-04-29 11:19:28


VIEW MORE
story-5
8 Classic Boxy Mercedes Designs That Have Aged Like Fine Wine

Slideshow: Before curves took over, Mercedes mastered the art of the straight line, and some of those shapes still look right today.

By Verdad Gallardo | 2026-04-25 12:05:49


VIEW MORE
story-6
Flawlessly Restored Mercedes 190E Evo II Heads to Auction

Slideshow: The 190E Evolution II shows how a homologation necessity became a six-figure collector icon.

By Verdad Gallardo | 2026-04-22 17:53:47


VIEW MORE
story-7
Electric Mercedes C-Class Unveiled: 11 Things You Need to Know

Slideshow: Mercedes is turning one of its core nameplates electric, and the details show just how serious this shift is.

By Verdad Gallardo | 2026-04-21 13:58:06


VIEW MORE
story-8
Mercedes EQS Gets A Major Update: Everything You Need to Know

Slideshow: Faster charging, longer range, and a controversial steer-by-wire system define the latest evolution of Mercedes-Benz EQS.

By Verdad Gallardo | 2026-04-15 10:35:34


VIEW MORE
story-9
5 Underrated Mercedes-Benz Models That Don't Get the Love They Deserve

Slideshow: These overlooked Mercedes-Benz models never got the spotlight, but they quietly delivered more than most remember.

By Verdad Gallardo | 2026-04-13 19:35:45


VIEW MORE