Melting contact in fusebox

Just don't use a real hot iron. A soldering station like this, about 50 watts, is all you need.

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There is a bit of skill involved with soldering. If you've never done it at least practice on something before you take the iron to your fuse blocks. The key points are to clean and prepare the surface and to get the soldering iron tinned properly. If you use some flux that will also help. Those brass brillo-like tip cleaners work very well but you can also use a damp sponge to prep the iron. When done properly the heat of the iron will instantly transfer to the copper lug and rivet, the solder will flow and you'll be off before it has any effect on the plastic.

 

@Erol Based on your pictures, you've got one (or a combination) of four issues:
- Poor contact at the spade terminal: This is highly likely as this is where you're seeing the damage (both housing and the wire terminal itself). Cleaning the contact and crimping a new faston connector would help a lot. You could move the wire connector to the open spade (as suggested by @Steve Magnusson ), but I don't think the spade is the issue--it's more likely that faston wire connector. Also, it's better to have that wire (feed supply) right where it's currently located (vs to the right) to spread the current more evenly to the three fuses.
- Poor connection at rivets: This is also a strong suspect. As has been mentioned by many others, this is a common failure point with soft metal and years of vibration. In this case, the heat generated at that rivet would be flowing to the wire contact and discoloring the connector/melting the housing. In this case, however, I would expect to see a bit of damage in the black fuse block plastic housing. While the temperature reflow threshold for the black housing is slightly higher than the silicon wire housing, the black housing abuts the rivet and will experience a higher temp relative to the wire housing. Tightening the rivets and/or soldering them would help here.
- Poor connection at bullet fuse interface: This is a possibility as well. The long lever arm of the fuse holder does not provide a lot of spring force against the fuse and experiences considerable fatigue over time (soft metal). This allows corrosion at the contact interface, which in turn results in more heat generation. However, the heat generated at this point benefits from better air transfer (it's not pushed up against the plastic housing) as well as dissipating against the black plastic housing before the wire contact housing. Cleaning the contacts and *gentle* bending of the fuse holder arms to provide more spring force will help.
- Additional load: As @Steve Magnusson pointed out, you've got an extra load in that terminal to the left. This will increase the current draw coming from the red supply line. Tracing this load and understanding the current draw will help make an informed decision on if this is a problem and how best to resolve.

In all likelihood, you're experiencing all four of these issues. The combination of all these heat sources results in temperatures high enough to discolor the wire terminal and melt the wire housing. Cleaning all the contacts, replacing the faston wire terminal, and tightening (or soldering) the rivet will reduce the heat sources.

As indicated, there are also replacement fuse block solutions that will eliminate this problem: Sam's (no-longer-avail), Birdman's, & Turtlefarmer's (mine). All of these use better materials (e.g. glass filled resin housing in Birdman's), better routing connections (e.g. PCB soldered in Sam's / Turtlefarmer's), and better fuses (e.g. blade fuses in Sam's / Turtlefarmer's). Any of these solutions will result in lower resistance (and, hence, lower heat + higher voltages) compared to anything you can do with the stock block. However, as mentioned by @johnk... , cleaning + modifying the stock components can improve the resistance significantly and provide years of service. Like everything else on your car, it comes down you how best you want to fix it (e.g. spend $$'s vs spend time and "DIY" vs "professional").

Hope this helps.

Also, thanks to @absostone for pointing me to this thread. I've had a crazy last few months with family medical issues and kinda fell off the fchat lurking. Hopefully I'm able to get back to my lurking soon...

 

"Any need to use a little dielectric grease on the contacts when reconnecting the wires?"

Always a good idea - reduces the possibility of corrosion/increased resistance at the terminal joint.

 

Dont mess with those things....just buy yourself new fuseblocks. Saving you some major trouble !!

 

Thanks @Erol ! Already replied

On the dielectric grease, it's a fairly hot/contested topic in the automotive EE world. While the grease will somewhat prevent oxidation on the exposed metal, the argument against is that the metal-to-metal mating surface shouldn't oxidize in the first place (both due to no chance of air penetration and slight vibrations in the vehicle). Personally, I don't think it hurts nor helps very much -- so my advice would be to just go with what makes you feel comfortable . Just don't overdo it if you decide to put it on there.

 

Nice work. I would address all of them and call it done. As for dielectric grease, you can do without it unless your car is stored in a lousy environment and the fuse cover isn't on when in use or in storage.

 

When I had my GT4, I simply removed those bullet type fuse blocks and installed glass-tube type fuse holders. They were not 100% same size to the old ones but fit well enough. They worked much better.

 

I don't believe the grease to be necessary at that point in the car. But it doesn't hurt anything.

 

1978 GTS. I had problems with the original fuse blocks losing contact at the rivets. So I soldered the upper and lower rivet connections on both blocks. I removed each block before soldering as I soldered both the front and back rivet connections. If you decide to do this be sure an take pictures as it's easy to install the plugs on the wrong connector. And yes I did melt the plastic a little as I had to use fairly high amps to get the things hot enough to solder but no harm no foul. I also found that cheap Ebay torpedo fuses for the high amp circuits are useless. I thought after 40+ years I should change the original fuses with pretty new ones. The fan circuits actually melted the plastic part of the fuse so I put the originals back in. Real nice! If you decide to change to more modern fuses either Birdman's or Turtlefarmers work great, however at least with Birdman's the labeled plastic covers don't fit.

Barry

 

Pretty sure that that's a self-resetting circuit breaker that someone added (and quite ballsy if it was just in there loose with those bare studs exposed ). Try an internet search using:

Fasco Type 1110 circuit breaker

and have a look at some of those pictures. Here's its brother (Fasco Type 4110):

https://www.ebay.com/itm/143568401134?epid=568104880&hash=item216d57f2ee:g:A3AAAOSw~eRgEG2-

and a more modern version (with a cover):

https://www.amazon.com/dp/B08Z7QF6L5/ref=redir_mobile_desktop?_encoding=UTF8&aaxitk=bf307028631e5e33e1106d1edfdcf753&hsa_cr_id=9370701370901&pd_rd_plhdr=t&pd_rd_r=7db84474-8380-4dd5-9f8b-462d90ae8bae&pd_rd_w=wA5so&pd_rd_wg=S4zjj&ref_=sbx_be_s_sparkle_td_asin_0_title&th=1

Can you determine what the wires are for, or where they go?

 

One of the most difficult things to diagnose/sort out is a previous owner's wiring "misadventures." Adding aftermarket components is often accompanied by really poor electrical work with no indication or written "log" of what was done or why.

I don't know anything about XDI ignitions but I doubt the installation instructions include adding a "hanging circuit breaker!" The best way to troubleshoot, unfortunately, is with the stock wiring diagram in hand, going through the various circuits. Often the best thing that can be done to a recalcitrant electrical system is to toss all the aftermarket stuff and restore the wiring to stock.

If you are comfortable doing so, get a copy of the XDI installation instructions and check out the circuitry/components involved. Or have a shop you trust do so.

 

Was the XDI indicator light green, red, or off? I'm inferring OFF, but want to confirm. If so, this means the XDI unit itself has no power.

Erol, is your XDI unit a silver case, or black? Also, what's the serial number (you'll find it printed on the side of the case). I'm asking because the wiring diagram for each is slightly different, so not posting a diagram in this reply because I don't want to confuse things further.

It may help if you can post a picture of the XDI, so that we can get a look at the wires/harness splicing.

It doesn't, no.

The XDI does need the installer to include additional circuit protection, but it's not normally done in the manner. The circuit should have two inline 10-amp fuses from the main 12V to the DFU relays (each relay gets a 10amp fused feed.) The wiring also suggests a 2A fuse from 12V to XDI (to protect the unit). So in any case, a single 10A breaker isn't satisfying anything in the correct way.

Looking at the 3 wires that were on the breaker, I can't really determine HOW it was wired because it makes no sense. I think that the YELLOW wire on the breaker might be the 12V feed to the XDI, but I've no idea how the black and white wires got invited to the party.