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Voltage Regulator question.


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Hello guys. I wonder if you guys can give me a bit of advice. My truck was driving fine, but one morning, it wouldn't crank because of a dead battery. It turns out the alternator wasn't charging it. So I replaced the alternator, but it didn't work. The charge output I get is only around 11v. So I took it to an electrician and he's telling me I need a voltage regulator. He found this "wire bridge" where he says the voltage regulator goes. I would love to get the regulator, but can you guys explain why it worked before with this bridge? I don't understand why it would work then and not work now.  Below are some pics of my entire engine bay. Maybe you guys can identify the actual regulator if it's there. The red circle indicates where "wire bridge" is located. 

Thanks again for your immense help. Your knowledge and willingness to share it is very much appreciated. 

 

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Looks like the electrical system was converted to work with a later '78-'79 620 internally regulated alternator. If you replaced with a 521 external regulated alternator it won't work. Take that one back and get the '78-'79 620 alternator.

 

'78 and up car alternators will work and they have more output but they are larger and are a very poor fit.

 

 

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Usually the regulator plug is snipped off and the existing wires are connected and others removed and then the plug goes onto the existing wire harness.

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Thank you Mike! You must be right. I have the L20b on it, but he alternator I got was for the 521. Would this be the right one? https://www.amazon.com/23100-B9800-23100-B9801-23100-B9802-23100-B9805-23100-N9800/dp/B00BWYG9R6

 

or this one: https://www.oreillyauto.com/shop/b/alternators---starters/alternator/f7cab2ae3cc0/v/a/8235/automotive-truck-1979-nissan-620-pickup

Edited by Gabriel
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Yes it is! The 23100-B9805 is for the camper option truck and has 3 extra amps more output that the regular 35 amp alternator. I know. It's not much but might as well go for it.

 

 

All '78 and up Datsun cars (A10 HL510, S10 200sx and the 720 truck) were 50 amp but are larger and a tight fit around the lower radiator hose and fitting above it and when tensioned they swing down and hit the idler arm just under it. I got one to work on my 620 but was never happy with it.

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  • 2 weeks later...

So the update is that I changed the alternator and the water pump. Both are working, but I get this grinding noise from what I think is the alternator. What do you guys think? Should I replace it or will it go away?

 

 

 

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4 minutes ago, Gabriel said:

will it go away?

Usually this is a no brainer and better look into this before your on side of the road.

 

I would take a look at the lower side of the alternator to make sure the case is not hitting the idler arm on the frame. The more you tighten the belt the more you push down on the case to hit the idler arm. maybe loosen the alt so its more away not near the idler.

Maybe take the fan belt off, run it and see if it still does the noise. then spin alternator with your hand to maybe feel for roughness.

To me it sound like a timing chain or tensioner but if this didnt happen till you indroduced a new part I would think new part. The water pump IM sure its NOT

 

make sure the alternator is snug bolts on the ears and on the adjustable slide.

 

521s need alot of maint. You better get good with this rig.

My 521 had so many proplems that the average guy if I gave this away would have been in back yard or junkyard years ago

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