Alternator dying?

[Bandit]

I realize that there are tons of threads regarding the alt but im just getting more and more confused.

I have a 1970 Datsun 510 with a stock L16 and all of a sudden the charge on my battery dropped down to 11 volts and the charge light came on in the dash.

 

I recently uninstalled the hood latch to install a new hood release and grease up the mechanism and saw in a different thread that there might be a ground somewhere around there? (I dont know  :confused: )

I have only had the car few a couple of weeks and the only time I noticed a good drop in the voltage was when I was running my stereo, wipers, lights, and a space heater the PO wired in.

 

After I noticed it I drove home so I didnt end up stuck on the side of the road and while the car was still running took the positive connection off the battery and the car instantly died.

 

I have also read that sometimes cleaning the connectors for the alternator will help with problems like this?

Sorry for all the questions!

[datzenmike]

Be sure you hood is not closing down and touching your positive terminal. Look for a burn mark. If it did then the body would have tried to be positive and the ground cable on the head would have tried to discharge through the body sheet metal. Normally the voltage regulator mounting bolt has a ground wire from the neg side of the battery. Possibly it's fried?

[Bandit]

The hood does sit lower on the battery side now that Ive fixed it and the terminals are not insulated so I will go take a look at that and report back :)

[datzenmike]

A square of rubber mat works for this.

[banzai510(hainz)]

put positive towards the firewall. It should be that way anyways.

 

if 11volts and hood up its to late already. soemthing popped

 

 

After I noticed it I drove home so I didnt end up stuck on the side of the road and while the car was still running took the positive connection off the battery and the car instantly died.

I have done this myself. everything must be off. If lights on It will kill it. But others on here say dont troublke shoot like that , trust a volt meter

 

ck it at idle the voltage then rev it up and put the lights on and maybe the heater. Hopefully its still about 12.8 or above.

stock 35 ampers load down EZer so youll know if its charging good or not. Mayb 50 amper I have alot on and its fine about 13.8v

[Bandit]

With the hood open and idling its sitting at 12 volts, played with different combinations of things running but the only things that make a huge difference in voltage were the wipers. The moment i turned it on to the first setting it dropped down to 11 volts and on the second setting the wipers just stopped where ever they were.

I even turned everything on including the fog lights and it dropped down to 9 volts but the car kept running.

Any ideas?

The positive is pointed towards the fire wall and I cant really get a good idea of where the hood drops down above it, only thing i noticed by looking at my hood was this lil patch of nasty.

 

Thanks for your help again guys

[datzenmike]

Yeah that's not charging at all. You're running on what's left in the battery.

[Bandit]

Crap  :hmm:

Hopefully I can pick up a replacement fairly cheap (out of work till shoulder heals  :hairy: )
Ill see how much it is to get it fixed or see if I can get a good deal on a 77 200sx alt and belt.

[banzai510(hainz)]

like mike says it running off the battery now. Unless you see soemthing obvious not hooked up on the alt.

 

a 77200 is a external volt reg alternator. Just remember the standard 50amper will use the thicker bolts in the ears of the alternator. the stock l16 uses the thinner bolts. 

You might have to ask for the Datsun 510 50amper option so they sleeve the hole for the thinner bolts..

 

just info there for you.

[Bandit]

Inside was really clean of the regulator but bottom was kinda gross looking.

[datzenmike]

You could get the '78-'79 200sx alt and convert your 510 electrical system over to the internally regulated alternator and never have to worry about that external box on the fender again.

[Bandit]

Going to take my alt apart tmrw and see whats not working and if I need to get a new alt i might as well go that direction.

[Boaty]

I swear by the Saturn conversion.... you can get one at almost any parts house. A little more involved.. but it is worth it in the end. Lots of info on that conversion here on Ratsun.

[banzai510(hainz)]

why even takew it aaprt . take to Napa and have it cked.

 

If bad replace it.

 

I have fixe the bushins before. next time the bearings are shot. Can only milk a cow so long before they go to slaughter.

 

 

you couls have popped the volt reg. but ck at Napa/autozone first. but most volt regs if bad the alternaotr still puts out but it OVERVOLTS

[Bandit]

Alternator was dead but they wanted to charge me more than it would cost to get a new one so I decided to take it apart and take a look. Bearings spin freely and nothing feels loose but the brush's do look worn. Going to take them in and get an opinion on them tomorrow.

 

While pricing out different alternators to use I got a bunch of people telling me to do a 1 wire GM alt switch. Havent really looked around much but has anyone done this? From what they were telling me the only hard part would be building a bracket to mount it on.

[I'm BLUE]

If the brushes are worn out that is typically the problem that I have seen. ( a rough slip ring can cause issues as well )

In my area ,,, parts stores will bench test an alternator for free ,,, as good or no good ( charge or no charge )

They can also test on your car/truck if you're willing to drive on battery reserve time ( not a good idea but do as you must if you must )

You might be able to call around and see if that works for you ...

 

I typically pop out bearings out/replace(might as well while there) and replace brushes as well as slip-rings if need be (typically I don't have to replace slip-rings... as you use a commutator brush to clean up existing ones as you know if they are good enough shape. )

 

Some IR voltage regulators can be fried and not allow the system to charge at all depending on the setup/make/model (fords) , but this doesn't apply to you I guess.

 

Datsun external regulators will tend to overcharge if bad (as previously stated) , but on zcar models some of the external regulators are mechanically adjustable via feeler gauge (think bigger points setup). I've fought bad/dirty connections with this as well....... ( like many have )

 

Alternator-Brush's,,, the wire connections can ever so slightly break (when worn severley down) and cause some erratic problems as well.

 

I'll look through my stash.

 

Good luck.

 

 

Take some pictures of the brushe's , slip rings , and rectifier then post them here :)

[datzenmike]

Brushes are about $8 so just get them and instal. Could be the problem and an easy/cheap fix.

 

The one wire GM alt. swap is not that easy. You still have to deactivater the old system. Remove the old external regulator and connect two pair of wires together. I've done this twice, once with a 240sx 90 amp alt. into my 710 sedan and once with an '02 Altima 100 amp alt. into my 710 goon, and and it works well.

[Bandit]

Well the brush's were pretty new it seems (Ive never taken an alternator apart before lol) so I was kind of stumped but someone local had a stock alternator lying around so I grabbed that and after getting it checked installed it.

I couldnt really tell if my battery was touching the hood or not but just because I should have a case over the connections anyways I put some on. The moment I closed the hood and re-opened it the positive case was dirty from touching the hood so it looks like thats what cause my alt to die.

 

Next little project will be to get the hood to sit right.

 

Thanks again for your help guys!