510, Apparent soft short, expertise, and gerenal thoughts please

[datzenmike]

15 hours ago, BZT8FS said:

Have you seen those go bad?

 

Not on a 510. They are special plastic that allows the wire inside to melt and break as a fuse should, but it doesn't catch fire. Sometimes the outside looks crispy/melted, sometimes you can's see anything wrong but the wire inside is fried. If it's damaged it may not be letting everything through.

 

I think the only fusible link is at the starter, can't see having one in the car.

 

Found 08 '71 and on 24022-89905 This might mean the earlier 510s didn't have one??? It was also used in the '74.5 through '76 240Z and 280Z.

 

 

Nissan uses their own code for fusible link rating in amps. Simply buy a foot of matching color OR what ever the rating is at any auto supply and trim to the same length. I don't know what the rating is, one manual I have says 200 amps but this is wildly high for a 38 amp alternator system back then. I would guess around 50 amp?

[banzai510(hainz)]

I dont think its a fusable link

 

whorn key switch during ON position? Or start vise versa

 

510s are pretty simple elelctrical

 

corrossion on connectors

Edited January 22 by banzai510(hainz)

[BZT8FS]

banzai510(hainz), I need to investigate further. I installed a higher capacity alternator, as I recall, it's from a B610, 80 amp output (foggy memory from decades ago) and I did find that I needed to replace the voltage regulator when I first started to get this project underway in the summer with my son. The white fusible link on the starter solenoid is looking very brown. I haven't been able to use my ohm meter on it yet but will soon.
I have ohm'd out the ignition switch with the connector off and it doesn't jump around and seems solid. No noticeable corrosion (car has less than 50,000 miles and always garaged) but it is definitely worth further investigation, I'll be scrutinizing everything closely now.

datzenmike Thank you for the table, very helpful. I can buy fusible from several sources. On my '73, I have a green fusible link connecting to the fuse box right in front of the headlamp relay, it's show on '73 schematic (wish I could post images....).

My fusible link at the alternator is white - it's not in the table above, any clues on what current level it's rated for (maybe it was originally pink, I'll get a bright light on it)? Regardless, I'm suspicious that it may be low for the higher capacity alternator I'm using.
Many thanks once again!!!

More soon.
 

[BZT8FS]

Correction, the fusible link on the starter solenoid is trying to be pink, it's faded and has some brown spots.
This is puzzling in that the alternator has to go through that link to power the car and charge the battery. I'm pretty sure the original alternator was more that 30 amps (pink) & even more puzzling is that the fusible link to the fuse box is 40 amps (green).

Seems backwards, have to think about this some more.

Pushing 80 amps through that 30 amp link is definitely gonna make it hot and fade the color.

[datzenmike]

Yeah I was thinking of the 521. The 510 was 33 and 35 amp and 50 amp from '71.

 

Yes I found the other fusible link.

 

Pink is probably a faded RED which is 50 amp.

 

 My 510 wiring diagram does show a White/Red going to the fusible link but there is a White wire from the alternator that by passes the link and goes directly to the battery. 

[BZT8FS]

Ah, good point I didn't think of that, make sense red becomes pink over time. Then the question is should I upgrade to the black 80 amp version?

Actually the folks that sell fusible link wire don't rate it by amperage, just by wire gauge and say that the correct choice is 4 wire gauges below the main wire, for instance, if the main wire is 14 gauge, the fusible link should be 18 gauge, etc. However, I'm not certain of the gauge of that wire from the starter solenoid.

[datzenmike]

No. That would be the sane as replacing a 10 amp fuse with a nail. The wiring would melt and catch fire before the nail would melt.

[banzai510(hainz)]

white fusible link on the starter solenoid is looking very brown. ?????????????????????

when one upgrades the alternator that much one needs to up size the feed wire. At least I know on Jeeps and Toyotas.Stoffregen Motorsports would know for sure.

 

You sure a 610s has 80amp??????  I seen 50/60amps atmost

Edited January 23 by banzai510(hainz)

[datzenmike]

North American 1200 and early 510 were 30 and 35 amp with the 510 changing to 50 amp for '72.  B-210, 610, 710, S10 and A10 alternators were 50 amp. Optionally there were 60 amp output on the 610, 710, S10 and the later A10 with Z20 engine and often these 60 amp were standard equipment in Canada.

 

It's very likely that the 60 amp alternator would easily fit the early 510/1200.

 

All alternators prior to '78 were externally regulated, all '78 and up were internally regulated. The internally regulated alternators can be used on earlier external regulated cars with a few minor wiring changes.

 

520/521 trucks used a physically smaller 25, 33 and 35 amp alternators, 620 trucks were 33 and 35 amp with a 38 amp on air conditioned models. The car 50/60 amp can be fitted to the 620 but it's very tight having the lower rad hose, frame rail and the idler arm close below it when tensioning the belt.

[BZT8FS]

No, not sure of the amperage rating, it's been several decades....I'll have to look closer.  It's an external regulator and was sourced in 1975, no later than 1976. Probably the 60 amp as datzenmike suggests. It's a bolt in with no mods.

 

Any ideas about fusible link ratings? https://www.wiringdepot.com/store/c/101-Fusible-Link-Wire.aspx

"A Fusible Link is NOT intended to be used in place of a fuse - only where a standard fuse cannot be used. When placing a fusible link, use a wire gauge 4 gauges smaller than the existing wiring circuit. If it is a 14 gauge system, use 18 gauge fusible link wire."

 

I've not found any of the factory ones anywhere. Ones advertised are "out of stock" - so I'm not certain that I even need one as banzai510(hainz)'s corrosion comment got me thinking, but in the instance that I do, I'm not sure which wire size to use, as indicated wiring depot is just one place but they all sell by wire gauge, not by amperage carrying capability. P/N 24022-89905 is the only one I find a reference to and appears to be the green one by the fuse box, I've not been able to locate the part number for the one on the starter solenoid.

[BZT8FS]

Although I do find several for the period 240Z, 71-73 like this one https://www.thezstore.com/product/3683/fusible-link-71-73-240z

No one seems to have any crossover numbers between the 240Z & 510 that I can find.

[datzenmike]

 

40 amp 0.5mm² is 20 gauge

50 amp 0.69mm² is 19 gauge

*

80 amp 1.25mm² is 16 gauge

 

*I would assume that a 60 amp is closer to above 50 than below 80 so 18 gauge?

 

il_1588xN.4835541188_aj40.avif il_1588xN.4835541188_aj40.avif

[BZT8FS]

Thank you!

Do you know the gauge of the white wire that the fusible link is attached to?
I haven't looked closely recently but aren't more of the wire runs in the harness the same gauge?

[banzai510(hainz)]

I dont think the fusable link is bad.

My 510 would on a few strans of wire. till I hit the Highbeams then bam all Black melted byt the connecter(bad)

[datzenmike]

The alternative is "could be anything" whereas you can jumper around the fusible link easily and for free to eliminate it. If not it could be the ignition switch.

[BZT8FS]

Point taken! I don't have much time to actually touch the hardware during the week - but I can think about all sorts of things.....

I'll diagnose.

[Rustbin]

I was looking for something else when I found this chart and remembered this thread. It is the fusible links locations and may be helpful for someone.

 

[BZT8FS]

Thank you Rustbin!

[BZT8FS]

 Alright, you all are correct, the fusible links are fine.

I've started buzzing wire branches, starting under the hood, which all appear fine, voltages what it should be (running on battery only)  and resistances, when I can measure them are less than 0.10 Ohm. Which is well outside of the accuracy of my various multi-meters.

 

I've uncovered on anomaly I cannot explain;

1) Key in "ACC"

2) Multi-meter between the + side of the coil and ground (another on the battery)
3) All fuses in place and wires connected (except the BY wire to the starter solenoid)

4) + coil is at 0V

5) pull lights to parking or to headlights

6) 0.15V appears at the + coil with parking lights on, 0.25V appears when headlights are pulled on

7) Remove the fuse for the flashers "F" and the voltage goes to zero
This is where I'd really like to be able to post images, in any event, I cannot trace any wiring that would put voltage onto the coil under these conditions.

 

Looks like more next weekend.

[datzenmike]

Doesn't look like it really matters much.

 

Make sure there is a solid ground from the negative terminal on the battery to the mounting bolt on the voltage regulator. By now the original cable has been replaced with one that does not have the ground wire for this. Any ground from the engine block to the body sheet metal will do. I run one from an engine bracket around the rubber isolator to the mount bolt but from an exhaust manifokd bolt to the firewall will also work. 

[BZT8FS]

Let's see now.

I failed to mention what happens in "Run" or "Start".

In Run with nothing else on, the voltage at the coil is about 1V less than the battery (11.6 v.s 12.6 for instance).

If anything is turned on (flashers, wipers, parking lights, turn signals, headlights, horn, etc.) voltage at the coil drops to ~8.5V.

Likewise with nothing else on but operating just the starter solenoid & starter, voltage drops to 8.5V.

Voltage at the battery never drops by more than 0.05V, it's pretty steady.

 

The negative terminal on my battery does have a separate line running directly to the voltage regulator ground.

Like you, I'm beginning to suspect a faulty or corroded ground somewhere, just haven't been able to locate it yet.

The hunt goes on.

[datzenmike]

As this is a points ignition in the run position the power to the coil positive should first flow through the ballast resistor which should drop the voltage to about 8v.

 

In the start position you should see battery volts on the positive terminal.

[banzai510(hainz)]

does the car run???????????

 

soft short.

I would clean and reset all connectors.

when you run a long wire its adding resistance.so from the fuse box to the coil I guess it could drop.

 

when you put the lights on with the HIGHS Im sure your going to be loosing more if not running

[datzenmike]

16 hours ago, BZT8FS said:

Let's see now.

I failed to mention what happens in "Run" or "Start".

In Run with nothing else on, the voltage at the coil is about 1V less than the battery (11.6 v.s 12.6 for instance).

If anything is turned on (flashers, wipers, parking lights, turn signals, headlights, horn, etc.) voltage at the coil drops to ~8.5V.

Likewise with nothing else on but operating just the starter solenoid & starter, voltage drops to 8.5V.

Voltage at the battery never drops by more than 0.05V, it's pretty steady.

 

The negative terminal on my battery does have a separate line running directly to the voltage regulator ground.

Like you, I'm beginning to suspect a faulty or corroded ground somewhere, just haven't been able to locate it yet.

The hunt goes on.

 

Tighten that regulator bolt. Nothing can be trusted simply by looking at it. And tighten the ground on the head and the positive cable where it mounts on the starter.

 

You should have about 8v on the coil positive in run or on and battery 12v in start.

 

 

[banzai510(hainz)]

you sure your battery is good?