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85 Nissan 720 2.4 Alternator.


Thomas Perkins

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Hi Ya'll.I was just wondering what amperage alternators everyone with 720's were using.I noticed the Nissan site show's 3 of them,all 50 Amps.All no longer availableMy Nissan Manual says gasoline models with 2WD use 50 and 60 amps,depends on where you live,including Canada and cab and chassis.It says 4WD use 50A and Canada 4WD use 60A.It also has 7 different alternator types with numbers and amp ratings. 7 types but only 3 on the Nissan part list.I guess if you were a die hard Nissan person,you would look on your alternator for the number and get your shot gun and go Alternator hunting.But any way,are there still shops and people that get there's rebuilt.I think every shop here is closed due to no one wanting to do that any more.Like carburetor shops are no more here.Our kind is a dying breed.Just like transmissions,no one wants to go in them,just sell you a new or remanufactured one.That's what I have.Another thing,if you go to a site to get a new alternator,some say 60 amps for a vehicle with A.C.So what is everyone's thought on this.I just ordered me another alternator bracket from Nissan.You never know.So if you have a A.C and use a 50 amp.Would it effect your electrical system.Think about this now.

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Up here they are 60 amp. I don't know... colder weather starts, maybe longer cranking? Battery needs to be recharged by the alternator faster? The starters are all gear reduction also for cold starting. Higher output just recharges the battery faster is all.

 

My '76 710 had a 50 amp alternator but I refit a 2002 Altima 100 amp into it. The headlights don't dim and brighten when the turn signals are on while stopped and idling. The heater fan blows and doesn't slow when you turn the headlights on at idle. Everything is better when you have more power than you need.

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I was looking at the 85 4x4 at the Nissan site and it showed just 50 amps,just looked at the 85 2WD and it does show some 60 amps types.Thanks Mike.I did get a new one in 6/22/2022.It started to have electrical issues,but I didn't think it was the new battery or new alternator.But after I recently put the new temp. sensor and sensor and new thermostat and new water pump and started it.The battery light came on.So I thought   I may need to tighten the alternator belt.We'll that didn't help.So I drove it to work and the light went off  after I picked up speed and the volt meter went to it's regular spot.But as soon as I went to a stoplight,the battery light would come on and volt meter would go down to 12 volts.So when I got off work I stopped at the Auto part store to test battery and alternator.The battery was good and alternator was bad.So I went into store and ordered a new warranty one.So I checked the one that was ordered and it is a 60 amp one for A.C.So I got home removed the like new alternator and it was the 50 amp one.So they gave me the wrong one back in June 22,2022.Some how I didn't catch it back then but the electrical fitting is different,the 50 amp one has a inlet that you connect the connector too and the 60 amp one is with a electrical wiring connector coming out of it and you connect the electrical connector to it and is bigger and heavier.So the Salesman ordered the wrong one back in June and I didn't catch it.The one before the one in June was a 60 amp one and the 50 amp one wasn't strong enough.It could of been what was causing my temp gauge not to work right,and I believe my water pump was good,my gas gauge stopped going to complete full.I believe all that stuff was all good,bad alternator.I have always used a 60 amp one but this one wasn't.Even my stereo wasn't working right.I put the new alternator in today,I just started it up and will drive it to work and see what happens.

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The temperature and gas gauges both are run on a regulated 8v power supply. This way the gauges don't read differently with engine off, idling or at full charge when driving.

 

It likely failed because after market alternators are of inferior quality and not because it was only 50 amp. Charge light at idle but charges normally when revved up is usually one of the 3 diodes gone bad or broken solder joint to one. Can't keep up on 2 diodes at idle but when spinning fast enough it can.

 

Go easy on the belt tightening. Too tight is rough on the alternator and the water pump bearings. The belt, half way between the alternator and the water pump pulley, should deflect 0.5 in. by pushing with your thumb.  A new belt is 0.3 to 0.4 in.

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These are junk reman alternators. You get to swap them regularly and if you keep buying them you get good at swapping them. You wouldn't notice the difference between a 50 and 60 amp. That is peak output at high rpms and your battery actually can't take that high of a charge. Unless running a winch or another extreme load a larger alternator isn't necessary. Most likely your problem with dimming lights is poor conductivity through connectors and aging wires. You can trick an alternater into higher output by putting a resistor in the sensing wire circuit but this is unnecessary. If you were to fill out an amp load chart for your truck you will find a 50 is fine. You can buy rebuild kits for these and do it yourself starting with new brushes, bearings and regulater. There really isn't much to go wrong. Newer cars have higher amp alts but they have multiple computers and all kinds of other electrical accessories. Also thier voltage regulation is controlled by the ECM so the alts won't work in our old trucks.

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My 2002 Altima (admit it's 20 years old and not that new) alternator works in my '76 710. I did have a Plymouth K car alternator in my 620 and it was regulated by the computer. I got the external regulator from a '70 Dodge and that got it working. High output alternators are needed because the sensitive EFI cars need a stable voltage supply. Old Datsuns that idle with heater and wipers on with headlights dimming and brightening at idle with the turn signal on just won't cut it.

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The lights dimming and blower slowing is probably a lot more due to high resistance connections, wire and corrosion than the alternator. They didn't do this off the showroom floor but 40 years later time has taken its toll. If I notice symptoms like this I take a small stainless or brass brush and "scrub" my connections after disconnecting them. There are a lot of spade and ring terminals exposed to under hood conditions and moisture. Battery connections, coil connections and even the alternater is made up of ring and spade connectors. A good scrub and some thinly sliced Emory boards for the female spades goes a long way to cleaning up electrical issues. The grounds seem to be extra important and 90% of 12v issues. After cleaning a dose of corrosion block afterwords slows corrosion.

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Well the lights back then were tungsten filament and all replaced with Halogen that draw more power. Also the power from the battery has to travel all the way into the headlight switch and back out to the lamps a round trip of about 8 meters ( over 26 feet) and does not include the wire to the ground on the other side of the lamps. I put the headlights on a relay and 12 gauge wire fused and directly to the battery. Later I switched to HID.

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Doing good now with the 60 amp alternator.My stereo lets me set the clock and change channel to next song.My A.C.and heating is brand new.Also has been rewired.Everything is different.A complete custom made system.One of a kind.My  volt meter is at where it should be.Was low with the 50 amp Alternator.It didn't effect the lights.About all my connections are new,including the fusible link.My truck is like new.Ground cable is new.50 Amp Alternator doesn't have enough ass for my truck.The salesman told me that they gave me the wrong 50 amp alternator back in June.A lot of my pig tails have dry rotted and are fixed.On my old heating and Air system,the 20 amp fuse kept pooping out.All that old Nissan stuff is gone.All my lights are new.My wife calls it my million dollar truck. I also had my Local Nissan site get me a new Alternator bracket.If they ever run out and I need one,then what.Got a spare...Tried to load the picture here,said it was too big,I will send the picture to my Imgur page and send it here thru the URL.Nissan even puts my name on the package.Bought so many parts from them.When they answer the phone and hear my voice,they know it's me.I will spend a dollar on my 720 in a New York minute...wkWkt7e.jpg

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