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#4626299 - 01/06/18 07:16 PM '86 Samurai alternator voltage too high
AZjeff Offline


Registered: 01/14/11
Posts: 2632
Loc: PV Az
I've had a couple of no-starts with the Samurai in the past month, after starting it and driving somewhere in town. When it wouldn't start the dash lights would dim and it made no starter noise. Luckily I could bump start it and get home. I thought it could be because it's only run on weekends and maybe only a few miles. It wouldn't start yesterday afternoon so I put the charger on it and it went to full charge in a couple of hours. Measured 15.09 volts on the battery after taking the charger off and 15.05 this morning. Out of curiosity I measured the voltage of the alternator and at idle it's putting out almost 16 volts and at 2500 rpm 18 volts. The battery is just over a year old, a NAPA. All cells show equal acid near the top. Apparently the voltage regulator has gone bad? I confirmed voltage against my Solar charger, it's .2v different. Electrical is not my thing, any help is appreciated. Can something outside the alternator cause the high voltage?
_________________________
86 Samurai 1.3 leftovers
14 RAV4 2.5 5W-20 PP *gasp*
16 Silverado 1500 4.3 Ecotec3, DI, AFM 5W-30 PP

Why know when you can guess?!


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#4626309 - 01/06/18 07:25 PM Re: '86 Samurai alternator voltage too high [Re: AZjeff]
danez_yoda Offline


Registered: 07/18/09
Posts: 464
Loc: texas
I think you have it. Regulator in the alternator is bad causing too high of voltage, Plenty of youtube videos on how to change them vs buying a new alternater.

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#4626386 - 01/06/18 08:43 PM Re: '86 Samurai alternator voltage too high [Re: AZjeff]
AZjeff Offline


Registered: 01/14/11
Posts: 2632
Loc: PV Az
Zuk in the wilds, we just got back from hiking to the top of that rocky little mesa in the background to see some ruins. The old girl still gets around pretty well. (I meant the Zuk.)
_________________________
86 Samurai 1.3 leftovers
14 RAV4 2.5 5W-20 PP *gasp*
16 Silverado 1500 4.3 Ecotec3, DI, AFM 5W-30 PP

Why know when you can guess?!


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#4626450 - 01/06/18 09:55 PM Re: '86 Samurai alternator voltage too high [Re: AZjeff]
Kurtatron Offline


Registered: 04/06/10
Posts: 166
Loc: Detroit
I love seeing older cars like that still being used. Like an old hunting dog, the owner never letís go of the old faithfal.

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#4626457 - 01/06/18 10:04 PM Re: '86 Samurai alternator voltage too high [Re: AZjeff]
andyd Online   content


Registered: 09/25/04
Posts: 7142
Loc: Marshfield , MA
Over charging a battery releases H2, A spark can blow the top of the battery off. AMHIK Fill the battery when the level drops. I wouldn't drive it much until it is fixed.
_________________________
'16 Camry LE STP synth 0w20 and STP filter. the Fridge

1994 Ranger ,the Rat, 5w30 dino, STP filter

'16 Camry SE, Valvoline HM 0w20 and OEM filter
Thick oil is better grin2

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#4626484 - 01/06/18 10:52 PM Re: '86 Samurai alternator voltage too high [Re: AZjeff]
AZjeff Offline


Registered: 01/14/11
Posts: 2632
Loc: PV Az
NAPA has VRs starting at $53 and brushes are $6 each so $70 with tax. Reman alternators start at $77 with tax. Which makes more sense?
_________________________
86 Samurai 1.3 leftovers
14 RAV4 2.5 5W-20 PP *gasp*
16 Silverado 1500 4.3 Ecotec3, DI, AFM 5W-30 PP

Why know when you can guess?!


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#4626507 - 01/06/18 11:18 PM Re: '86 Samurai alternator voltage too high [Re: AZjeff]
BrocLuno Offline


Registered: 09/06/15
Posts: 5512
Loc: Kalifornia Kollective
Also, please, please add a good new ground from the negative post of the battery to the alternator mount, or somewhere close. The alternator must see a real "0" to know what it is supposed to do ...

One of the problems of all aging equipment is the ground side. On the Pos side it has voltage to move things. On the ground side it has no voltage, but still must move the same current back to source. As time goes by and water does its thing, all those old connections on the ground side build up slight corrosion which makes each a semi-conductor. Then the current that must flow home will develop enough "voltage" to get the current through the connection. The added resistance means that things like the voltage regulator will not see battery negative as zero. They may see ground as a volt or two higher. This can lead to strange situations ...

The new grounds need to be crimped and soldered which will prevent future crevice corrosion. I use at least #8 AGW stranded wire. On older vehicles I always add one from the engine to the firewall to help with gauges and such. One from the bat neg ( - ) to the radiator support so the lights are brighter. And for sure, one to the alternator. Puts the whole system on an even reliable ground. Amazing how much better things run smile

The big battery neg cable was almost always just crimped and it has developed "crevice corrosion" in the years it's been on the road. And it's never been cleaned and lubed on the connection to the block ... So even if you clean the bolt and the cable eye, it will still be slightly off. The new added grounds will help. The big cable can take the starter load, but the new cables will take the running loads and keep everything nice and equal smile


Edited by BrocLuno (01/06/18 11:22 PM)
_________________________
Formerly in marine engineering. In an earlier life I owned my own petroleum tank truck, and hauled for the majors and independent's.

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#4626633 - 01/07/18 07:33 AM Re: '86 Samurai alternator voltage too high [Re: AZjeff]
eljefino Offline


Registered: 06/15/03
Posts: 32632
Loc: ME
You have also likely boiled your battery to death. I know you say the water level's fine but with it not starting...

Since the alternator is in runaway the battery is the only thing keeping voltage levels remotely sane by soaking up as much as it can. A sucky battery can kill a new alternator.

While you have it where you have it now, run it and put a voltmeter between the alt case/ bracket and battery negative terminal. Should be < 0.1 volts and ideally zero. Do the same with the big lug post and battery positive. You should clean the whole basic set of terminals up anyway but if you find something here more digging will be required.

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#4626711 - 01/07/18 09:19 AM Re: '86 Samurai alternator voltage too high [Re: AZjeff]
DBMaster Offline


Registered: 09/18/12
Posts: 5322
Loc: DFW
I'm just going to commend you on keeping a Samurai alive for over thirty years. They were excellent off-road vehicles, but they didn't exactly have a history of being reliable and long-lasting.

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#4626747 - 01/07/18 10:06 AM Re: '86 Samurai alternator voltage too high [Re: BrocLuno]
CT8 Online   content


Registered: 10/09/14
Posts: 10947
Loc: Idaho
Originally Posted By: BrocLuno
Also, please, please add a good new ground from the negative post of the battery to the alternator mount, or somewhere close. The alternator must see a real "0" to know what it is supposed to do ...

One of the problems of all aging equipment is the ground side. On the Pos side it has voltage to move things. On the ground side it has no voltage, but still must move the same current back to source. As time goes by and water does its thing, all those old connections on the ground side build up slight corrosion which makes each a semi-conductor. Then the current that must flow home will develop enough "voltage" to get the current through the connection. The added resistance means that things like the voltage regulator will not see battery negative as zero. They may see ground as a volt or two higher. This can lead to strange situations ...

The new grounds need to be crimped and soldered which will prevent future crevice corrosion. I use at least #8 AGW stranded wire. On older vehicles I always add one from the engine to the firewall to help with gauges and such. One from the bat neg ( - ) to the radiator support so the lights are brighter. And for sure, one to the alternator. Puts the whole system on an even reliable ground. Amazing how much better things run smile

The big battery neg cable was almost always just crimped and it has developed "crevice corrosion" in the years it's been on the road. And it's never been cleaned and lubed on the connection to the block ... So even if you clean the bolt and the cable eye, it will still be slightly off. The new added grounds will help. The big cable can take the starter load, but the new cables will take the running loads and keep everything nice and equal smile
Yes all the basics need to be done. I had intermittent no starts on the tractor last week and did a load test on the battery and further testing found the problem to be corroded battery cables where the fit into the terminal connectors. That actually is a common problem.
_________________________
"Don't let your preconceived notions get in the way of facts."
Geoff Metcalf

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#4626781 - 01/07/18 10:52 AM Re: '86 Samurai alternator voltage too high [Re: AZjeff]
AZjeff Offline


Registered: 01/14/11
Posts: 2632
Loc: PV Az
Thanks to the expert advice given I've spent some time with the Zuk this morning.

New heavy grounds from - battery to the alternator and firewall, to the rad support and engine to firewall soon.

Did the tests suggested by eljefino and found 0 from - battery to alt case and 2.2 from + battery to b+ post on alternator, which shows the difference between alt output and battery charge?

The battery holds a charge overnight within a few hundredths on my meter, is it maybe OK or not? 1 cup of distilled water brought all 6 cells close to the top.

So do I replace the voltage regulator and brushes (might as well) for $70 or drop in a reman alternator for about the same money? The Zuk sees about 3K miles a year so I'm not thinking a new Denso for $140 is necessary.

Big thanks for the help. I've owned the Zuk since '02, by far the longest of any other vehicle. Resisted the urge to go big with it since that just leads to chasing the next weak part. Every once in a while we talk about selling it but just can't.
_________________________
86 Samurai 1.3 leftovers
14 RAV4 2.5 5W-20 PP *gasp*
16 Silverado 1500 4.3 Ecotec3, DI, AFM 5W-30 PP

Why know when you can guess?!


Top
#4627038 - 01/07/18 02:49 PM Re: '86 Samurai alternator voltage too high [Re: AZjeff]
andyd Online   content


Registered: 09/25/04
Posts: 7142
Loc: Marshfield , MA
Heh heh BIL used to have a Tracker with Sammy for partz. When it got too rusty, he sold to a Mini Mote enthusiast (nut) I may have mangled the name. They were a Brit runabout 4wd mini. If the alt is factory, If you could find a Youtube showing how to R+R stuff on that alt, that would be good. Regardless, I would buy the regulator and brush kit maybe some bearings too. Alternators are hand assembled. To an extent, they are idiot proofed by design. Long before I realized this, I made scratch marks across things before I took them apart. I still do, cause I frequently push the bounds of idiocy in my attempts to fix things. grin2
_________________________
'16 Camry LE STP synth 0w20 and STP filter. the Fridge

1994 Ranger ,the Rat, 5w30 dino, STP filter

'16 Camry SE, Valvoline HM 0w20 and OEM filter
Thick oil is better grin2

Top
#4627144 - 01/07/18 04:18 PM Re: '86 Samurai alternator voltage too high [Re: AZjeff]
AZjeff Offline


Registered: 01/14/11
Posts: 2632
Loc: PV Az
A voltage regulator, brushes and bearings would be the same money as a rebuilt with lifetime warranty. It's not the OEM alternator. I love fixing things but sometimes it doesn't make good sense.

UPDATE: I bought a reman alternator from O'Reilly and put it in and am seeing the same high voltage across the b+ post and ground or - battery terminal. I guess I'm missing something here.
_________________________
86 Samurai 1.3 leftovers
14 RAV4 2.5 5W-20 PP *gasp*
16 Silverado 1500 4.3 Ecotec3, DI, AFM 5W-30 PP

Why know when you can guess?!


Top
#4627188 - 01/07/18 04:51 PM Re: '86 Samurai alternator voltage too high [Re: AZjeff]
mk378 Offline


Registered: 09/27/15
Posts: 1416
Loc: USA
Check your voltmeter on a known-good car.

The 2.2 volts drop on the live wire is a lot. With battery charged and most electrical stuff turned off, it should be a lot less than that. Maybe it is because the alternator is overcharging and the battery itself is drawing a lot of current though.

Also check the reference input to the alternator. The regulator senses the battery voltage through one of the small wires. If that voltage is lower than what is actually at the battery, it will overcharge.

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#4627209 - 01/07/18 05:13 PM Re: '86 Samurai alternator voltage too high [Re: BrocLuno]
willbur Offline


Registered: 06/06/13
Posts: 287
Loc: sw ohio
BrocLuno-

With all these grounds going everywhere; can ground loops can be formed which will drive the computer crazy? I think one ground with all the individual grounds connecting to it would be best?

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