One Dim Headlight and Hot-fuse fixed.

[cygnusx1]

Upon restoring my 72, I noticed a little melted spot on the fuse box cover. I don't like to see anything inside the car getting that hot so I investigated. I also had a dim right front headlight and figured it might be related. Well not really, as it turns out.

HOT FUSE:

The metal clips that hold the fuses are fabricated in two parts. There is a lower parts I call the plate, that is riveted to the upper part, I call the forks. The plate is crimped onto the wire, under the fuse box, and the forks are riveted to the plate. The forks are what stick up and hold the fuse. What happens is one of two things. Either you get some corrosion at the wire crimp or you get some corrosion in between the plate, and the fork, at the rivet point. This corrosion turns the connections into a resistor. A resistor passes electrical current and converts some of it to heat! Thus the fuse holder was getting very hot.

FIX:

I removed the bad holder from the fuse box by pushing back the tabs and sliding it back out of the plastic, which was already loose from being partially melted. I cleaned the metal by soaking it in vinegar for an hour. I rinsed it well, heated it up with a little torch and was able to feed solder into the crimp, and the riveted parts. I pplaced the clip back into the fuse box and secured it with a dab of epoxy. Upon testing, the temperature was no longer hot at all. It was now barely warm to the touch. This was the fuse for the marker lights.

ONE DIM HEADLIGHT:

I discovered that if one of the two headlight fuses are pulled, you don't fully lose that headlight. For example, pull the left fuse and the left light will only go dim, not off. Same applies for the right side.

FIX:

But both my fuses were good, as were the holder in the fuse box? As it turns out, simply unplugging the fuse box connectors, and re attaching them fixed the intermittent dim headlight issue. So this time, I re assembled with dielectric grease, after cleaning the contacts with vinegar, and a WD40 rinse. The contacts all appeared clean but they were obviously still in need of attention. The connectors up by the radiator support had already been addressed with a cleaning and greasing.

I hope this helps someone out in the future. :classic:

[TomoHawk]

)The DeOxit products (D-5 and D-100) are made specifically to remove the oxidation and lubricate electrical contacts, and work better than WD-40. WD-40 was designed to displace water.

[cygnusx1]

UPDATE: The park/tail/dash lights began to fail again occasionally, and would return by wiggling the fuse. The fuse was getting very, very, hot. It turned out to be that the metal fuse clip itself had become annealed from the heat over the years, and my re-soldering of the lower wire connection. There was no spring tension left in it to bear down on the fuse. It could no longer hold the fuse tightly. I cut two lengths of silicon vacuum hose about 1/4"+ in diameter, and as long as the fuse. I wedged them on either side of the fuse clip, parallel to the fuse. The pressure from the silicon tubing, presses the clip tangs tightly into the fuse for a great connection. No more heat, and reliable lights!

I see it as a great temporary solution until I can get a new fuse box.

Edited October 31, 2010 by cygnusx1

[Darrel]

msa fuse block and zsondabrain headlight and parking light harnesses should take care of everything, at least for the 240z.

[Zs-ondabrain]

Thanks for the Plug Darrel.

Dave, It is, as you say, only a temperary fix. Even the new fusebox will overheat, seen it a few times on the new MSA box already. Not saying you have to buy my upgrade, but I am saying that you need a relay in your Parking light circuit. Or this will keep you busy for a long time.

Plug my PLH in and never worry about it again. Not to mention you won't even have to replace your fusebox because the PLH only uses a 12 volt signal at 0.30 amps. That means you won't have 15 amps going thru the fusebox or combo switch anymore. The relay will handle that current from now on.

Think of it this way, $60 for the PLH at MSA Versus the $200 fusebox also at MSA. your choice. once again, not pushing my product, pushing the idea that a relay is what you really need, whether it's home made or store bought.

Dave

[cygnusx1]

Yup another Winter project. I have seen yours and it's a nice piece. I'll keep it in mind for when I pull the trigger.