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Marios280Z

Recommendation for new radiator and elctrical fan for 280Z

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One thing that's not often mentioned with the electric fans is the extra draw on an already weak electrical system.  The 60 amp stock alternator typically can barely handle the lights on at idle.  Those fans can draw some amps.

I have been thinking about it a lot. Perhaps stupid question, but how would I know that my alternator is struggling to keep up with power demands when i have my lights on and the fans are spinning (dimmed lights? slower fan operation?engine problems due to less charge capability of the system, including undercharged battery? blown fuse?)? One of the things I have been thinking about doing to offset the power demand is to replace light bulbs with LED bulbs. All for marker lights, and rear lights. What would be left are the head lights, which frankly draw the most. But I think if I was able to find replacements for the side markers and rear that would help some.

 

Alternatively, what do we have as an option for a replacement, more powerful alternator that is drop in replacement? I hate to go this route because that sounds like an expensive rote and i have already spend more than planned on the radiator project.

 

On the other note, there is a progress. This car will race this Sunday!!

 

Did some wiring 

post-30354-0-93266000-1443798374_thumb.j

 

Fits nicely now. Still quite a bit room left

post-30354-0-65876700-1443798393_thumb.j

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The dash voltmeter is a good indicator of whether or not your alternator is keeping up.  Note where it sits with everything off.  That's your base battery charge reading.  Then, after the engine is started and running at higher RPM you'll see it jump up to some high limit.  That's the alternator regulator limit.  As RPM drop toward idle speed you'll probably see the needle drop toward the normal battery charge state.  When it hits the number, that's equilibrium, power out = power in.  If it drops lower your battery is discharging.

 

The gauge isn't very precise so you'll probably just see it sitting on the everything off state.  You'll feel good when you're driving and worried when you're idling.

 

Many people have used the early 90's Maxims alternator.  It's a 90 amp output and will bolt in.  But it needs a pulley change and rewiring.  Simple in concept, but the pulley bolt needs an impact wrench and some grinding of the housing might be needed to get the pulley aligned.  I have one sitting in my garage, completed, but I've found that the small improvements here and there, relays and connection cleaning, have put my stock ZX alternator to where it can keep up, with my stock electrical parts, no fans.

 

I've also found that the cheap parts store alternators vary in their output.  The first one I used was weak.  The factory issued, old, grimy, wrecking yard ZX alternator was much better than the shiny "new" parts store reman.

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Well folks, it has happened.At autocross this morning. It was only 8pm last night when I filled the rad with coolant.Here is the final productpost-30354-0-66841400-1443975573_thumb.j

post-30354-0-14914100-1443975516_thumb.j

post-30354-0-00996500-1443975593_thumb.j

And here she is this morning

post-30354-0-88970200-1443975671_thumb.j

Still few small things left to do but I will write about it later.Time to race...

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She did well yesterday. Didn't even brake a sweat. Now I need to find a way to bring in a wire form the engine bay to inside for my manual switch. Any good that will not cause me disassemble half of the dash?

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Awesome. I don't know much about racing... Were you in a stock class with (hopefully) similarly performing cars?

 

And as for your wire back into the interior from the engine bay, I don't have any silver bullet for that. Unless there's some function that you have stopped using such that you could repurpose an old wire for a new application, I don't have any great suggestions. Push a wire through the existing grommet?

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CO, I'm new to the aturox racing as well, so I'm not really competitive, yet. I participate to have a little bit of fun and learn fine car handling skills in a controlled environment. Because my car has some modifications done compared with stock version (springs, shocks, bigger and wider tires and brakes) I  cannot compete in a stock class and therefore I get put in a more competitive one. The 280 is not super competitive car in its class unless you really heavily modify it. For example where I am right now SCCA rules put me along side with BMW Z3 M coupe with famous S54 engine. That car easily makes twice as much horse and torque and handles better :) So, as I said I don't go for trophy, I go for an experience. If I want to win a trophy I sit on my race bicycle:)

 

Back to the wire, pushing through the grommet was one of the options I was thinking off. just need to find one that will lead to the cabin and I can find it without dissembling the dash. 

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I think there are only two electrical grommets that go through the bulkhead wall. The big one on the driver's side (for the EFI) and the big one on the passenger side (for everything else). I'll take a look at the wiring diagram and see if I can come up with any bright ideas on a wire you could repurpose.

 

This is for a wire that goes hot when you hit your override switch, right? Connects to green on your control relay?

 

You done any other mods like a headlight relay upgrade?

 

 

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Yes,  It is the green wire form the relay that I wanted to hook up to a switch. The other side of the switch would have to go to a low current 12V source. I was thinking about utilizing one of the mystery  wires you have mentioned reside under the the glove box area.

 

I have not done any other electrical work yet, no head light relay. Should I? I have been thinking about upgrading the stock lights with something modern that MSA or blackdragon guys offer.  I believe at least one of the stores offers HD wiring harness that would should be put on with the new lights. But that's' a different topic :)

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I was asking about mods like a headlight relay upgrade because if you would have done that mod, you would probably have an unused wire going through the grommet on the passenger side that could have been re-purposed for your fan override.

 

Independent of your fan controls though. Yes, I would recommend a headlight relay upgrade. The original switching system is overtaxed by the headlight current and I'm continually surprised they didn't use relays in the original design. They used a relay for the fricken horns, but they didn't use any for the headlights???

 

You've got a 78 right? Already has an internally regulated alternator.... Just musing ideas.

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just a thought on your wire path - my 78 has a double blank-off rubber plug for the holes in the firewall that were for choke cables in previous model years. it's on the drivers side above the pedals/below the throttle linkage. i know this because i pulled my efi and installed carbs, using this rubber blank to route the choke cables.

you can poke a hole through the rubber (it's thick) and pull a wire (or choke cable) through with an air/water-tight seal.

easy-peasy and no messing w/the dash.

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just a thought on your wire path - my 78 has a double blank-off rubber plug for the holes in the firewall that were for choke cables in previous model years. it's on the drivers side above the pedals/below the throttle linkage. i know this because i pulled my efi and installed carbs, using this rubber blank to route the choke cables.

you can poke a hole through the rubber (it's thick) and pull a wire (or choke cable) through with an air/water-tight seal.

easy-peasy and no messing w/the dash.

Ahh, I don't believe I have seen them, but I will take a second look this evening. Thanks!

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I have found those two rubber plugs. In my car they are used to wring in AC pipes inside the cabin.But I did see that there was plenty of rubber left to poke a hole and feed a small wire.

On a different note, I had a bit of a malfunction happen to me on my way to work this morning. I don't want to highjack this post, but I'm going to mention it here since we have been talking about alternator here. As I was driving down the ride all of the sadden my lights went off. My dash went dark, and my head lights went dark. Radio worked, engine was spinning and electric fans were ON at that point. I turn the head light switch back and forth,but there was nothing. I continued driving down the streets for few more minutes, came to the intersection, and turn the blinker on, it worked. I then attempted to run the head lights on again, and this time they came ON,but still no dash lights. Few minutes later I pulled into my work parking lot, left the car running and got outside. My had lights were still on, but my marker lights as well as my rear lights were off. My front orang lights that are normally on and go brighter with blinker on were off, but turning the blinker on would make them flash. My rear blinker lights would flash as well. This far I have not had any other problem with my lights after dual Dan install. It did not seem like alternator was struggling a lot with fans on. Dash voltage gage would drop just a bit when idle and fans on, but probably less than if I turn the head lights by themselve.I also tested at idle with headlights and fans on, and again you could tell that fans slowed down a bit when lights went on, but I was still showing way over 12V on the dash volt gage. All that's test were done week and a half ago when I finished my fans install. Throughout the week Ice been paying attention to the volt gauge when fans kicked in and I did not see anything abnormal. What could be happening here? So you think my fans have anything to do with my light malfunction or is it coincident? I have not checked any fuses yet, but I will later today when I come back home.

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 I think I'd go looking for a  poor or bad ground. I have used a  2'-3' piece of elec. wire with alligator clips on each end to add a ground to suspect circuits. Quick & easy way to complete a circuit, then find the bad ground or add a new one.

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I have found those two rubber plugs. In my car they are used to wring in AC pipes inside the cabin.But I did see that there was plenty of rubber left to poke a hole and feed a small wire.

On a different note, I had a bit of a malfunction happen to me on my way to work this morning. I don't want to highjack this post, but I'm going to mention it here since we have been talking about alternator here. As I was driving down the ride all of the sadden my lights went off. My dash went dark, and my head lights went dark. Radio worked, engine was spinning and electric fans were ON at that point. I turn the head light switch back and forth,but there was nothing. I continued driving down the streets for few more minutes, came to the intersection, and turn the blinker on, it worked. I then attempted to run the head lights on again, and this time they came ON,but still no dash lights. 

The headlights are on a separate fusible link.  Maybe it came loose.  Not sure what else is on the circuit.  

 

The dash lights on my car will go off when the tail light fuse blows.  Same circuit.  So if you don't have dash lights, you may not have tail lights either.

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The 78 fusible link for the headlights does headlights only. Nothing else is on that circuit.

 

What's the state of the issues now? Is everything back to normal, or are there still lights that aren't working?

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Still have the problem. I know why the lights are not on:post-30354-0-40577800-1444702313_thumb.j

post-30354-0-35854600-1444702334_thumb.j

15A fuse totally disintegrated. Also melted the fuse box cover. Took replacement fuse and tested with only marker lights on and dash lights on.Them turned the head lights on and all still looked OK. Car was off when I was doing this. The biggest question I have is what could have possibly caused it??

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A simple shorted tail light bulb socket could blow the fuse.  I had one of those.  But the fuse destruction and high heat under the cover shouldn't have happened.  Have you had the fuse box assembly out?  Maybe you shorted some wires behind the that fuse.

 

You said it happened all of a sudden.  Implying that something moved and shorted while you were driving.  I would check all of the things that you've worked on recently.  I didn't catch where you wired in your fans and relays.

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I have never disassemble the fuse box. The fuse broke in half as I was trying to pull it out,  I did not find it this way. Either way it got hot over there. I  was driving in  a straight line when things went dark on me. I have installed the fan relay and the fuse at the very front of the car, to the left of the RH headlamp and to the right of the coolant overflow tank. There already was a bolt not used by anything so I just attached the plastic relay box and also sued that bolt to provide ground to the relay. Then there is a power wire going straight to the battery and one to the override switch (eventually  I will have it hooked up). Then there is power wire going straight to the fans. Grounds from the fans are attached to the car body by a bolt right underneath the carbon container. From the relay there is also a signal wire going to on of the terminals on the thermoswitch. The other terminal of the switch is connected to the + terminal on the ignition coil. I honestly don't know what I could be looking for on the new installed system. It really appears that it is nowhere near the circuit responsible for the rear lights, dash lights, and the dual function front orange light. Also, before I replaced the fuse I verified an I did have the back up light, but the glove box and the ash tray light was out.

Edited by Marios280Z

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The fuse is supposed to melt when it gets hot.  The only explanation for getting that hot at the fuse connection is that you had high resistance there, creating a hot spot.  A balance between the local hot spot and heat dissipation that allowed the cover to melt before the part of the fuse that was supposed to melt melted.  In short, dirty/loose fuse contacts.  Common on the 240Z's, I believe, not so much on the 280Z's.  I'd clean them all up.

 

Weird that you have multiple problems happening at once.  As noted, the headlights and the tail lights are two different circuits.

 

I went back and did see this though - "I was still showing way over 12V on the dash volt gage".  How way?  Could be that the excess heat was caused by excess voltage, and excess amps.  Maybe your VR is going bad.

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Zed Head,  I have always been showing over 12 volts when engine is running. When engine is off the dash volt indicator shows just a little over 12V. I though that when alternator is charging the nominal value would be around 14-14.5V. What do you mean by VR?

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VR is short for voltage regulator.  14.5 volts is good, using a good meter.  The dash gauge is isn't very good.

 

I only asked because it was undefined.  One man's "way over" is 16 volts, anothers is 14.5  I'm a numbers guy.

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Well that's a bummer. So looking at that fuse and the cover, here's my forensic analysis of the whole situation... (Warning... Heresay and theory alert)  :)

 

You have (or had) a dead short somewhere in your parking light system. That dead short occurred spontaneously as you were driving. Hit a bump? Something maybe that had been very close to shorting for some time finally picked last night to be the time when it went the rest of the way? Or maybe it's related to the electrical work that you have been doing recently?

 

That spontaneous dead short blew the fuse so violently that you ended up with arcing sparking inside the glass tube along with ionized air and metal mist from the vaporized fuse material. That ionized air and metal mist allowed an arc to form (just like welding) and that arc not only allows current to continue to flow, but it also produces mucho heat. Certainly enough heat to crack the glass and melt the fuse block plastic.

 

So, you've got this dead short in your parking light system and a fuse that is still passing huge current even though the metal strip is long gone. You're pulling many amps through the dead short, and because of that, your headlights go dim (which looks to you from the driver's seat like they went out completely).

 

Then after some period of time, the arc finally stopped. Maybe the fuse metal burned back so far that the arc could no longer be sustained. Maybe when you flipped the headlight switch back and forth a couple times, you were able to break the arc? Maybe whatever shorted in the first place became spontaneously unshorted? Maybe the high current melted and opened a wire somewhere?

 

In any event, the high current draw stopped, your headlights were able to come back to better brightness, and everything else, other than the parking lights, went back to normal.

 

And for those of you who are wondering "OK, so if this is all true, then why didn't a fusible link blow?" Well here's why... For whatever reason, in Datsun's infinite wisdom, there are a bunch of circuits that hang directly off the alternator with no fusible links between the alternator and said circuits. They are a direct connect to the alternator, and in the case of a hard fault, are happy to suck down as much current as the alternator is willing to produce. I don't know if this is a design oversight, or on purpose for some reason, but that's the case, and yes... The parking light system is one of these "non-link protected" circuits.

 

So, my first question is... Is the short still present, or did it fix itself as mysteriously as it occurred?

 

You can't simply check with an Ohmmeter because all the bulb filiments will make it look like a short to ground (even though it might not be). I would put a new fuse in that spot (like a 5A fuse?) and turn the parking lights on while you watch that fuse at the same time.

 

if the parking lights come on like normal, then you've unfortunately got a continued mystery. If that fuse goes up like a flash bulb, then you need to start disconnecting things until you find out why.

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Well that's a bummer. So looking at that fuse and the cover, here's my forensic analysis of the whole situation... (Warning... Heresay and theory alert)  :)

 

You have (or had) a dead short somewhere in your parking light system. That dead short occurred spontaneously as you were driving. Hit a bump? Something maybe that had been very close to shorting for some time finally picked last night to be the time when it went the rest of the way? Or maybe it's related to the electrical work that you have been doing recently?

 

That spontaneous dead short blew the fuse so violently that you ended up with arcing sparking inside the glass tube along with ionized air and metal mist from the vaporized fuse material. That ionized air and metal mist allowed an arc to form (just like welding) and that arc not only allows current to continue to flow, but it also produces mucho heat. Certainly enough heat to crack the glass and melt the fuse block plastic.

 

So, you've got this dead short in your parking light system and a fuse that is still passing huge current even though the metal strip is long gone. You're pulling many amps through the dead short, and because of that, your headlights go dim (which looks to you from the driver's seat like they went out completely).

 

Then after some period of time, the arc finally stopped. Maybe the fuse metal burned back so far that the arc could no longer be sustained. Maybe when you flipped the headlight switch back and forth a couple times, you were able to break the arc? Maybe whatever shorted in the first place became spontaneously unshorted? Maybe the high current melted and opened a wire somewhere?

 

In any event, the high current draw stopped, your headlights were able to come back to better brightness, and everything else, other than the parking lights, went back to normal.

 

And for those of you who are wondering "OK, so if this is all true, then why didn't a fusible link blow?" Well here's why... For whatever reason, in Datsun's infinite wisdom, there are a bunch of circuits that hang directly off the alternator with no fusible links between the alternator and said circuits. They are a direct connect to the alternator, and in the case of a hard fault, are happy to suck down as much current as the alternator is willing to produce. I don't know if this is a design oversight, or on purpose for some reason, but that's the case, and yes... The parking light system is one of these "non-link protected" circuits.

 

So, my first question is... Is the short still present, or did it fix itself as mysteriously as it occurred?

 

You can't simply check with an Ohmmeter because all the bulb filiments will make it look like a short to ground (even though it might not be). I would put a new fuse in that spot (like a 5A fuse?) and turn the parking lights on while you watch that fuse at the same time.

 

if the parking lights come on like normal, then you've unfortunately got a continued mystery. If that fuse goes up like a flash bulb, then you need to start disconnecting things until you find out why.

I like your theory and in many cases you have mentioned I've been thinking the same things.

 

Last night when I found the fuse, I have put a new fuse (the same amperage, 15A) and with the engine off I first turn the positions lights on, so 4 markers  plus the front dual purpose light. Watched the fuse for red glow, but there was nothing. So I got braver and turn the headlight switch one position further to turn head lights and rear lights, at which point I took cover in case of spontaneous inferno...Luckily (or maybe not so) there was nothing happening... This morning, whether it was smart move or not, I decided to drive the car to work. I left the fuse box cover off so I could monitor the fuse. I probably spent more time looking for a red glow on fuse than I looked at the road. Nothing happened. No problems. I suppose I should now go and examine every light that is on this circuit and clean the connections. 

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