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fuse box melting!

Dale B.

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I have a '73 240Z that I picked up a little over a week ago. While driving at night I noticed a burning smell coming from the car and my tail lights went out. upon further inspection of the fuse I found that the the inside terminal for the PArking/tail lights had melted a hole in the base and cover of the fuse box! Doh! that terminal is now basically free floating. The fuse was cracked and had a white powdery look to it. Also it was broken in half. I replaced the fuse and every thing worked until I had to use the lights again yesterday for a 20 min trip. Same thing started to happen but I got to it before the fuse disintegrated.

I'm thinking that somehow that terminal is grounding out right there since it is not blowing the fuse but baking it instead. Could a short somewhere else cause it to heat up at the fuse box, or is that gonna be the source of the trouble? Any ideas would be most appreciated!


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Dale, that is a known problem with the early Z's. In fact, even my '68 Datsun Roadster had the same issue.

Replace the whole unit. It's going to be your best option. I don't know how long I fooled around re-wiring, clamps, soldering, etc... before I just gave up and bought a new fuse box.

If I remember correctly, that unit isn't cheap (around $100 or so). Check with Les or Dennis at Classic Datsun Motorsports.

Get a new one. Don't mess around with used stuff because you'll be in the same boat again.

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  • 3 weeks later...

I have the same problem as Dale. Same fuse block also.

I've seen somewhere on the net where some body describes a way to "rebuild" the fuse box. Something to do with making new solder connections. Anybody know where this is at? A link?

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Temporarily, yes.

I know it's kind of the cheap way out right now, but that is all I can afford. All I'm looking for is links to information where some have soldered up the fuse block to help overcome the melting problem. I've seen it before, I just can't find it. Once I find it, then I'll make an informed decision about whether I can trust that sort of fix or I need to buy new.

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Dale and Kmack - If you want a quick cheap fix you can simply take out the fuse box to access the wiring and splice an in-line fuse holder into the parking light circuit. It can be done fairly easy and cost you almost nothing. Make sure the new wire is of adequte gauge and the fuse no more than the 20 amps for that circuit. You may find that the heat has melted or burned up some of the wiring, so you may have to go back a few inches to get to good wire. This will work, but getting a new fuse box is the cleanest and real fix. If you look at any old Z you will find the taillight fuse holder has melted the plastic box on most of the cars. Many of them have a inline fuse already spliced into this curcuit.

It is caused by corrision forming between the connections on the back of the box where the wire lugs are riveted to the holders. The tailight circuit draws a fairly good amount of juice so this connection gets the hottest and melts out the box. High resistance generates the heat. Load the curcuits and use the finger test to see if any of the other fuse holders have also had it. If they are too hot for your finger, they are also corroded.

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The Achilles Heel of the Datsun Z.

Along with it's notorious propensity to rust due to thin sheet metal, you'd think that people would shun this car. But like a gorgeous woman that you know is HIGH $ Maintenance, people keep at it.

The fuse box problem has had write ups in bunches of posts. The following are but a small sampling and I'm sure there are others I've missed and others could add to:





Addressing the topic briefly and succintly.

General repair and restoration of the fuse box is as follows:

If the fuse box is still generally intact, i.e. no melt through, or damage, then remove from the car and clean all the contacts. Get a small wire brush, the type that looks like a small pipe cleaner or like a miniature toilet bowl brush and remove all corrosion from the clips that hold the fuses. You can also use a small piece of sandpaper rolled up into a tube and insert it as you would a fuse and rotate it.

Carefully bend all the clips so that they hold the fuse firmly. Check the rivet that holds the fuse clip. You can solder the back of these, but be careful as too much heat will melt the plastic that holds the fuse clip in place. I personally prefer to put the fuse block on a small anvil and using a nail punch, hammer the rivet so that it will make better contact with the wire below.

Check ALL the fuses for CONTINUITY. Don't just visually inspect them. Too many times the fuse appears intact, only to be the cause of electrical failures. Preferably, get new fuses. The time and effort to clean up and ensure that a 30 year old fuse is useful is way too much considering that you can usually find the fuses available at any auto parts store. Heck in some supermarkets and drug stores, the automotive section has the fuses.

Lastly, check the connectors for the fuse box. Any corrosion or discoloration of the metal should be removed. Remember, corrosion first appears as discoloration, then as it progresses, looks like a weird texture. This causes RESISTANCE. Resistance causes HEAT. Heat causes meltdown and problems.

In the situation where the fuse box has already melted, you CAN find replacements.

MotorSports, Victoria British, ZParts, ZBarn, are but just a few of the places that have them available. Yes, they are spendy but then again not as expensive as watching your Z car burn.

And regarding upping the fuse to a higher amperage? DON'T. If you have a problem with a circuit, check out the circuit, don't just put a 20 amp fuse in place of a 10 amp. The fuse is your SAFETY, and it's designed to blow if the current exceeds it's rating. If a fuse continues to blow, it's a sure sign of something NOT being right.

When a fuse blows in your house, do you automatically go out and replace the fuse with a higher amperage one? or do you first try to find out what caused it?

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  • 1 month later...

I am dealing with the same problem on my 1970 model 240Z.

My advice to anyone having this problem on a 1972 or later model Z is to get a new fusebox as soon as possible. Unfortunately, you just can't get a new one for a 1970 model Z.

I did the recommended fix several years ago on that car by soldering the rivets. Maybe I didn't do a good enough job, but the fix lasted about 5 years, then the fusebox melted beyond my ability to repair.

It has taken me a year and a half to actually locate a suitable replacement fusebox. (This one has very minimal melt damage. and looks salvagable).

While looking for a replacement, I ended up having to build a replacement fusebox using parts from Radio Shack. Not the best solution, but hey, it worked in the interim.

Had I just bought a new fusebox in the first place (They were available at the time, but I was a poor college student) I'd be a whole lot better off today.

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