Wiring to Replace or Not, While the engine is out Options

[DennisV]

How problematic is the now 50 year old wiring? Some existing threads seem to suggest they're pretty vulnerable, yet I don't see wiring harness included on most "while the engine is out" todo lists.

Are there any that are consistently so troublesome that they should get proactively replaced even if they appear good? On the 914-6 it appears there are two for the engine bay (complete engine and alternator). That's $500 USD right there.

For reference, I'm not attempting a complete restoration. Just trying to get our car safely and reliably back on the road. The engine, transmission, and suspension components are out of the car. I've found a couple previous owner wiring additions, but they have been easy to remove.

My impression has been that if the wiring, insulation and connectors look good they probably are good. It's not like the copper wears out. Perhaps this is naive.

P.S. New plug wires are already obtained. I have no intention of removing the main harness.

[Superhawk996]

My impression has been that if the wiring, insulation and connectors look good they probably are good. It's not like the copper wears out. Perhaps this is naive.

Not 100% true.

Corrosion can spread up into the stranded wire - looks good but can be high resistance.

This is usually what happens in the yellow starter solenoid wire that runs from the ignition switch to the solenoid on /4’s. Everyone thinks it’s fine but resistance is too high and it begins dropping voltage across it when cranking. Honestly, that start issue is one that plagues way too many teeners because very few take the time to address the root cause (high resistance).

The thing the /6 has going for it is carbs and a whole lot less wiring than the /4 has to/from fuel injection sensors and actuators. Likewise it doesn’t have as many ground points that mater to reliability.

You can check resistance end to end. Should generally be very near 0 ohms. Resistance per foot is published for various wire gages. If you end up with something that reads high measuring resistance, or looks suspicious look up resistance per foot and do the rough calculation.

Flexibility of the insulation is critical. If it’s getting stiff and seems prone to cracking when bent tightly, replace it.

[windforfun]

My impression has been that if the wiring, insulation and connectors look good they probably are good. It's not like the copper wears out. Perhaps this is naive.

Not 100% true.

Corrosion can spread up into the stranded wire - looks good but can be high resistance.

This is usually what happens in the yellow starter solenoid wire that runs from the ignition switch to the solenoid on /4’s. Everyone thinks it’s fine but resistance is too high and it begins dropping voltage across it when cranking. Honestly, that start issue is one that plagues way too many teeners because very few take the time to address the root cause (high resistance).

The thing the /6 has going for it is carbs and a whole lot less wiring than the /4 has to/from fuel injection sensors and actuators. Likewise it doesn’t have as many ground points that mater to reliability.

You can check resistance end to end. Should generally be very near 0 ohms. Resistance per foot is published for various wire gages. If you end up with something that reads high measuring resistance, or looks suspicious look up resistance per foot and do the rough calculation.

Flexibility of the insulation is critical. If it’s getting stiff and seems prone to cracking when bent tightly, replace it.

(IMG:style_emoticons/default/agree.gif)

I actually had a section of Monster Cable for loudspeakers go bad on me inside the house. It corroded internally & turned green.