Park Tail fuse melting box?

[Linda]

You will be able to see the stuff come off in 30 min or so. I would cut the plastic off the wire and clean it or if too bad, strip it back to clean wire with a new ring terminal. Once done it should last a long time.
Linda

[svwilbur]

Have you seen these drawings I did?

http://www.kendo-usa.org/datsun/datsun_ ... _69_70.pdf

http://www.kendo-usa.org/datsun/datsun_ ... _69_70.pdf

Curtis, thanks for the pointer. I also looked at some of the other files you have in that same directory location. they are all helpful.

I would love to see a schematic laid out over a top shot of a roadster diagram that showed where all the connectors are located and path of each wire. what a project that would be!

it would also be nice if some vendor offered new wiring harnesses so we could easily replace all the wiring and connectors that have gotten worn over the years. but there was not enough roadsters sold and still existing to be practicle. not like my 57 Chevy truck which you can pretty much build from reproduced parts. finding an exact wiring harness for that was a breeze. and it all fit and worked.

I guess that may be what motivated you to layout the schematic to help yourself and others in patching and fixing worn harnesses and chasing down problems. actually it looks like you made your own harnesses by the looks of someof your pics in the images directory. nice work.

I have a couple of chewed up connectors by the clutch pedal I need to replace sometime but I am affriad the wires may break trying to remove them. that is a project for a later time when I get some new connectors and removal tools.

I also have another connector on the engine side of the firewall that has a broken wire off the connector block. it looks like someone patched around it with an inline fuse. looks like it goes to the starter. to fix that I would have to splice the existing wire and add on to it for length and with an appropriate connector to fit back into the connection block.

[Curtis]

Have you seen these drawings I did?

http://www.kendo-usa.org/datsun/datsun_ ... _69_70.pdf

http://www.kendo-usa.org/datsun/datsun_ ... _69_70.pdf

Curtis, thanks for the pointer. I also looked at some of the other files you have in that same directory location. they are all helpful.

I would love to see a schematic laid out over a top shot of a roadster diagram that showed where all the connectors are located and path of each wire. what a project that would be!

it would also be nice if some vendor offered new wiring harnesses so we could easily replace all the wiring and connectors that have gotten worn over the years. but there was not enough roadsters sold and still existing to be practicle. not like my 57 Chevy truck which you can pretty much build from reproduced parts. finding an exact wiring harness for that was a breeze. and it all fit and worked.

I guess that may be what motivated you to layout the schematic to help yourself and others in patching and fixing worn harnesses and chasing down problems. actually it looks like you made your own harnesses by the looks of someof your pics in the images directory. nice work.

I have a couple of chewed up connectors by the clutch pedal I need to replace sometime but I am affriad the wires may break trying to remove them. that is a project for a later time when I get some new connectors and removal tools.

I also have another connector on the engine side of the firewall that has a broken wire off the connector block. it looks like someone patched around it with an inline fuse. looks like it goes to the starter. to fix that I would have to splice the existing wire and add on to it for length and with an appropriate connector to fit back into the connection block.

You're welcome. I make new harnesses but right now I have more work than I can handle with my little bit of spare time. Chores are not getting done around my house at the moment. Finished a couple pieces yesterday.

[svwilbur]

Curtis and Phil and others,

I have it back together. testing connections and fuse box.

if I leave the park lights on for 5 minutes they do warm up. I was having a hard time using just my fingers.

I have a infra red thermometer that shows with all power off they are at 82-84, that is the temp outside today.

if I turn the park lights on it evetuually goes to 108 after 5 minutes. since power is flowing should I expect some heat?

how warm hot is a bad connection or worse?
where do you think it should stabilize at if I left them on while driving an hour or more?

should they be ambient temp or higher?

is 50 or 75 degrees higher normal?

so far I only let it get to 108 which is 25 degrees Fahrenheit more than ambient temp.

I did not try to clean the front connectors by the radiator as they look kind of short and may break if I try to remove them. these may be a poor connection. the rear lights have newer wires from the lights. those look ok.

also the connectors on the driver fender have not been cleaned. again I am kind of affraid to mess with them this close to trying to drive to solvang meet.

one problem is I have to drive at night 30 minutes on friday and saturday to get back to hotel. the rest of the time I dont think I need the lights.

so I am wondering how hot they can get before melting or causing issues. what is the normal range?

[Linda]

Stacy,
You should be able to disconnect the neg battery cable and then just spray liberally with electronic contact cleaner those connectors you mentioned. Don't even disconnect them if you are worried about them crumbling. The spray can still clean and potentially dislodge crud. Make sure to let everything dry before you reconnect the battery cable.Spray into the back of each connector and the liquid will make it down to the tabs.
Sounds like you are making progress.

Linda

[svwilbur]

yes , some progress. it was really kind of intense turning the circuits on the first time, waiting for unexpected fireworks......

I have some electrical skills but you never know what you might have missed or screwed up without knowing it, pushing some wire, whatever.

in general should the fuse area for a curcuit warm up some when juice is flowing?
like the headlights or parklights fuses?
how much heat would be "normal"?

[svwilbur]

I guess I could let it get warm a bit and then check the parking light connections to see if any of them get warm. maybe that would point me to a given connection with issues?

[Linda]

In electrical, doesn't resistance=heat, and so any dirt, corrosion, broken wires etc would increase the resistance---> heat, and if so with enough resistance, a melt scenario can occur.....
You could pull the park bulbs and spray into the socket as well
Linda

[svwilbur]

I already pulled all bulbs on exterior and cleaned and sprayed. only one was a bit corroded the front passenger sidelight. all the rest, park in front, headlights, sidelights front and back, back tail and brake lights all were clean. sprayed anyways.

I sanded, cleaned, sprayed two frame grounds in front and one on frame in rear by tail pipe. and put more electrical tape on places that might rub in the tail,park wiring including rear corners Linda recommended.

so are you saying that there should be no rise at all in temperature around the fuses when a circuit is in use cor for long enough? not even 25- 50 degrees or so?

[Linda]

I don't know the answer to that one, I only know general principles Have to get a guru to weigh in.

Linda

[Curtis]

Movement of electrons through the copper will equal some heat. The wire has a maximum capacity for voltage and amperes it can carry. We have a couple EE's on here that can explain this I'm sure.

So add to the maximum capacity of the wire any other problems of resistance and corrosion, bad connections, too much load for the wire gauge to carry, broken strands, shorts and many other things and you can get warm or hot wires and melting insulation.

IF you want to be really nerdy you can look at stuff like this.

https://en.wikipedia.org/wiki/Joule_heating

[svwilbur]

im just wondering in practice does everyones park tail curcuit warm up a bit when they are on for 10 minutes or an hour or is it expected that no heat is generated at the fuse since the curcuit was built heavy enough to have no resistance. and in practice no heat is generated on most peoples roadsters park,tail fuses?

it appears that my fuse gets warm and that heats up the brass connector.

it was kind of hard to tell as I noticed that pointing my infra red thermometer laser at my finger displayed 80 degrees but 1/2 inch above it displayed 96 degrees. prior to discovering that the fuse above the park tail fuse was reading as warmer and that curcuit was not even on as it was a head light but I only had parking lights on!

once I figured that I could see what the temp was going up on the park temp fuse. it was also showing the fuse was hottest not the holder, but maybe that is off by 1/2 inch laterally. I did not check that.

I was just upset that it was still getting warm. I did not see how warm it would get. it raised from 82 ambient to 108 Fahrenheit in 5 minutes or so.

I started by just using my fingers to test for warmth but after a while it was hard to tell as my fingers got desensitized what with heat and pointy brass fuse holders, so I switched to the infrared thermometer.


but if a fuse is rated for 20 amps then does it blow at 21 or 25?
is it magically cool to 20 amps and superheats at 21 or 25 and blows the fuse?

it seems that it would get warm at some lesser current and proportionately get warmer as you approached the fuses max capacity...

or is that just not how it works?

[msampsel]

im just wondering in practice does everyones park tail curcuit warm up a bit when they are on for 10 minutes or an hour or is it expected that no heat is generated at the fuse since the curcuit was built heavy enough to have no resistance. and in practice no heat is generated on most peoples roadsters park,tail fuses?

it appears that my fuse gets warm and that heats up the brass connector.



but if a fuse is rated for 20 amps then does it blow at 21 or 25?
is it magically cool to 20 amps and superheats at 21 or 25 and blows the fuse?

it seems that it would get warm at some lesser current and proportionately get warmer as you approached the fuses max capacity...

or is that just not how it works?

I am not the worlds expert on fuses but I do know V=IR and Maxwell's equations etc el ...

I'm sure all fuses will heat up some when the current flows they have too.
Electrons in motion in wire is some heat, which is why there is no 100% transfer of power in even the best
power lines. Infinite resistance is no heat (stick a piece of wood very large R in the V=IR between the battery posts for example (no heat)).

The fuse must get hot to melt and blow. So a 20 ampere fuse at 20 amps is going to be warmer than
ambient temp so that when it gets to the breaking point it will blow (melt).
A fuse is there to protect items, wires, E motors etc. And skinny wire's insulation melts (smokes don't ask me how I know this ) at too much current (and they are
copper very low resistance the R in V=IR!)

If you are not blowing fuses I would not worry about it.

When you get a lose connect then you get melting as the gap jumping from
spark across the electric potential gap creates more heat dissipation ...

Sleep well drive on and carry extra fuses is my humble (LOL) advice

PS If you want to know when they blow run an experiment with various fuses.
E.G. measure your current in line with an ammeter at the 20 amp fuse position,
and step down to below the current level you measure with fuses and see where it blows.
I would not go this though LOL. Possible I'm overthinking here

[redroadster]

It seems you dont buy that arcing is causing the fuse box melting

As I understand the fuse is not blowing but melting the fuse box
Which suggest there is not a overload on that circuit but a loose arcing connection
Have you started this car up in the night ? ,with no light ,you can see the arcing easily . Might have to tap the box slightly

[Curtis]

The wire gauge that Datsun used for the circuits is quite small. People will say that it has worked for 40 or 50 years. My opinion is yes and no based on all the problems people have on here.

I have been using this calculator to check on some of the circuits I build.

http://www.gtsparkplugs.com/WireSizeCalc.html

Based on the amps for a turn/stop bulb rated at 2.1 amps and tail/park bulb .59 amps and the length of the run to the rear from the firewall the wire is undersized. The rear harness has wires up to 15 feet long and then you have to add in wire in the dash as well.

It seems that if everything is new and clean and in the case of the fuse box tight the whole thing works fine. Add 40 or 50 years and it doesn't work so well anymore based on what people are saying.

I upgrade the wire one gauge for the lights. 2 reasons for this, I can't get the right color wire for all the circuits at the smaller size and second based on the calculator it should be.

I'm not an EE but do have a background in electronics and people have created these cool tools to use like the calculator. The first harness I built for my car was way overbuilt. I've learned to scale it back to a reasonable level now.

As to the fuse getting warm some warming is apparently normal. I switch to ato fuses and have never bothered to check mine for heat. But then my wire is kind of over sized too.