'71 240z - that old melted fuse box question - with a small twist . . .

[Madeline Larson]

So, I'm new to restoring vehicles, and I'm getting ready to start working on my dad's '71 240z. Lo and behold, one of those problems is a fuse box that is melting due to corrosion on the contacts. My question is this:

- What exactly is causing the corrosion? I have a replacement box, but I don't want to drop it in and then have the same issue occur all over again because I never took care of the actual problem.

I've seen that many people are going through and replacing the wiring harness. Is the original wiring still ok, should I be looking into replacing it simply because it is 37 years old? For what reasons would I need to replace the existing harness?

--- Madeline

 

[Zed2k]

I think a combination of age related corrosion in the loom etc, and the heavy current loads that these boxes carry especially the headlamp feeds, might be worth doing a headlamp sub loom mods with twin relays to remove the current loading from the box and then upgrading to a new blade type box from Motorsport Auto these look quite good thinking of doing it myself.
Hope this helps.

 

[abas]

Welcome to the club Madeline

I second zed2k about the headlight sub loom and the MSA replacement fusebox, although both are expensive, but cure a known weakspot and give some peace of mind

Usually the melting fusebox is caused by corrosion in the contacts on the back of the fusebox. The design is very bad, as the fuse holders are riveted to the wires, which of course you can't disconnect and clean. damp/corrosion gets in and the connection goes bad and it gets hot and then your plastic fusebox melts, usually round fuse number 2 down on the right hand side, which takes most of the load through it. I have heard suggestions of dunking the damaged fusebox in vinegar for a few hours until the connectors all go shiny, and that this cleans the corrosion out of the contacts.

In a money no object situation I think we would all like a new wiring loom. My experience is that getting the original connectors to make a new loom is difficult, unless you replace all the connectors with new type. If the loom on your car has already been badly 'interfered with' might have to replace it anyway, as it could be dangerous as well as old. I unwrapped the engine and dash loom on mine and had to replace some wires where the insulation had hardened and cracked, as these were heavy load carrying wires. I opted to leave the rest alone as it only carries small loads.