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.

vettdvr

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

csumt76

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.

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

csumt76

Yes, I agree with that. The harness for a 92 should be easily available, although it may not be cheap.

Moviela

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

MBTECH2003

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.

CalifSLK

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.