True about the replacement, the heat and oil cause the insulation to become brittle with time. Some cars have disintegrated and become unreliable due to wiring insulation problems. I have experienced it on a few early and mid 80s Volvo 240s, they used environmentally friendly insulation expecting the cars to last and the wiring to last but they missed the mark by a decade or so as cars 10 years to 15 years old (nothing for the 240 in areas not heavily salted) would start to see electrical gremlins. I rebuilt a lot of an engine harness on a '82 240 in the dead of a winter snow storm after a wire shorted to the intake, I had failed to get the connector block secured back on the firewall and it flaked the insulation off due to being too green when being green wasn't the in thing to be...
Live and learn...was a frustrating and maddening experience but a good one in hindsight...
If you need to clean the wire of enamel coating (for the magnet wire) use an aspirin (don't breath in the stuff) and melt the aspirin on the wire with a soldering iron or torch. The aspirin will remove the coating from the wire and then all you have to do is wipe your wires with a damp cloth and your iron tip clean with damp sponge or cloth, flux your connections, tin them and splice in your new wire (if going the soldering route... ) Either mechanical ratcheting crimper or the soldering of new wire is going to have to have clean wire to make it work.
I have seen black wire rot as well as green wire rot where the insulation became permeable but the harness sheathing did not and the wires sat in water eventually causing them to short out with one another or fail due to the rot. In those cases it was best not to be moving the harness around if working on the car or bad things could result. My '82 torched a lot of the harness and it was a 3 day job putting it back together. I still have the Wavetek Multimeter I bought to do that job, it was $100 in 1992.
David
