Alternator- regulator issue?

[jcard]

Hi gents. It's been a while since I posted anything regarding my 1972 521 as she's been running great for quite some while.

I've some pretty prolific oil leaks from I think the from of the engine which I'd love to fix but probably that's for a later day.

 

The immediate issue is the charging system. I checked the battery terminals and they seem ok, all other connection points appear sound,

tight and I've not changed anything in some years. Perhaps 10 years ago I'd replaced the alternator with a rebuild and it seemed to be good.

I can't imagine putting more than 3000 miles ( and that's a stretch ) since as I just don't drive her much.

 

Here's what I observe. The truck starts normally and runs well. Normally the ignition light goes out after a few seconds. Occasionally

it does not. Most often the ignition light comes on a few minutes after the truck has been running a while. I took a VOM and measured the voltage across

the battery terminals before the light popped on and I was getting about 14.5 volts. After the light popped on the reading dropped to somewhat over battery voltage- 12.x. Before this happens I heard loud clicking( nearly a knocking ) from the voltage regulator. I could swear I smell a mild burnt 'something'

smell from the engine compartment but very faint and I can't see anything. Both wires to the battery are cool, doesn't exhibit any overheating due to faulty contact.

 

So my question is it the alternator or the voltage regulator that needs attention or both?

 

Jerry

[datzenmike]

Is the alternator oil covered? Try pressure washing it. Oil could be all over the brushes. I've driven through deep puddles and the alternator light comes on for half a block. It's just water on the brushes. Oil would be worse.

[racerx]

You can take it to autozone or oreillys and get it check

[d.p]

Or just replace it. $30

[datzenmike]

And you'll be back in a week. 

[racerx]

Or just replace it. $30

...always wise to diagnose before buying and replacing.

[banzai510(hainz)]

get the Innova 3721 battery /volt meter , or sililar versions out there

plugs in the cig lighter.  they work great. you can tell what going on w/o getting a meter on the battery. works great... tell whats happening before you die on the side of the road.

 

if 14 volt at 2k then you put lights on and goes to say 12.5 still at 2k rpm then I say the alt is going bad.  if you have a spare Volt Reg swap in as it ezer to swap.(should have a spare anyways)

 

 

clean the ignition fuse battery post.Use molded end battery cables

[Doctor510]

Use a local alt/Gen/starter re-builder.

[mainer311]

The alternator in these trucks are so anemic from the factory. If your alternator is dead, your best bet is to install a hitachi alt from a 510 with A/C. It's a no brainer with double the output of the OEM unit, and very minimal mods to make it fit.

[banzai510(hainz)]

I always had issue with the smaller bolts breaking with the heavier alternators. Esp on lowered 510s

most 50ampers use the bigger bolts . or request a 50amper option and they sleeve the hole for the smaller dia. L16 bolts. If a L16 is installed

[datzenmike]

The 510 alternator does not clear the idler arm below it very well when the belt is tightened. If you use a shorter belt the alternator hits the lower rad hose. If it fit, everyone would have put them on long ago. The 521 and the 620 both have physically smaller alternators for this reason.

[mainer311]

The 510 alternator does not clear the idler arm below it very well when the belt is tightened. If you use a shorter belt the alternator hits the lower rad hose. If it fit, everyone would have put them on long ago. The 521 and the 620 both have physically smaller alternators for this reason.

Well man, then go look at my build thread. The 60A Hitachi alternator fit perfectly, no hitting anywhere. Plenty of clearance with steering idler, and cleared rad hose inlet. I know you’ve been around a long time, but quit being a naysayer.

[datzenmike]

Doesn't fit the 620. At least not the L20B engine. Pretty sure the 521 is the same.
 
I said it doesn't fit very well. I had to swap a 720 mount in and a more swept back 280z lower rad inlet for clearance. I think a shorter belt and to get it on you had to slip the belt on the pulley then put the bottom mount bolts on. Once the belt wore down you soon run out of adjustment and hit the idler arm.

 

 

Now maybe the L16 sits higher on the frame than an L20B and as Hainz said the L16/18 mount is two bolt, the L20B is 3. Below it looks like the alt. bolts are above the block bolts.

 

 

Here are 2 different mounts. IIRC the top is the 720 and the bottom the L20B. The top one raised the alternator. If you have three bolt you're stuck with them.

 

[wayno]

Well man, then go look at my build thread. The 60A Hitachi alternator fit perfectly, no hitting anywhere. Plenty of clearance with steering idler, and cleared rad hose inlet. I know you’ve been around a long time, but quit being a naysayer.

I wonder what alternator mount you are using.

I do know if one uses the Z22 alternator mount the big alternator will fit the earlier L20b engines, otherwise it has to tilt away from the block too far and then the alternator can hit the idler arm, there is no other way unless one makes their own mount which is what I did.

Even the factory made the alternator mount different than the early mounts to fit the larger alternator on the Z22 engine.

[banzai510(hainz)]

Well Im just saying its not a 10min job to convert to a 50amper(it should be) on a truck. 510 yes its EZ. Esp to somebody that is new to Datsuns and DONT knows the difference between the years, bolt sizes and belt sizes ect. and adjustment type( I use a turn buckle tension set up and that limits it even more)

 

 

I have run into getting Mitshibishi 35amp  alt and I need to get another belt!!!!! WTF

 

Ezeist is just get another one of the same type.35amper

 

 

just shut the heater off when at the stop light

[mainer311]

If you’re already in there, 100% worth the time and money to avoid having to do dumb shit like turn your blower fan off at stop lights.

[banzai510(hainz)]

Be honest I dont have to do that . and I have H4 lmaps with harness.

 

alot of Datsun kids are below average on mechanical skills. Just hate to see something go bad even though its very EZ

 

 

My turn buckle limits my alt size I can use so it had maybe a inch adjustablilty or it would hit idler arm. I said Fuck it and went back to a 35amper. 

[racerx]

I stayed with my stock one been running that style for 15 years as DD. Back in the days I looked into swapping out more alternator seemed too much to do for a little gain..you know like putting header on our cars.

[jcard]

I've been reading the replies with interest. I'd love to switch to a greater output alternator if I could. I have a reasonably well equipped machine shop

so I could possibly make some different mounting solution but not knowing what to make I will probably stick with an OEM part. Unless I could get both

and experiment. Having once had a 1973 240z ( I purchased it new in 1973 and sold it 13 years later with 296k miles on it) I wondered if an alternator from

a 1972 240z could work or is out of the question. I can't recall what kind of voltage regulator it had.

 

Jerry

[datzenmike]

External regulated through '77. Internally regulated from '78 and on

[DanielC]

In my experience, getting a 50 amp alternator from a similar year Datsun is a direct bolt on, the external voltage regulator does not even need to be changed.  The positive and negative wires should be changed to something thicker to handle the extra current.

You might have to get a new belt, to keep the laternator closer to the engine, and away from the steering idler arm.

 

There is a black wire that goes from the alternator case to one of the screws that holds the voltage regulator to the inner fender.  This wire is very important, it grounds the cab to the engine, and the battery.  If this wire is missing, the cab will try to ground through the throttle cable and destroy it and possibly leaving you with a throttle stuck open.  There is also a black wire from the alternator case to the negative battery cable.

 

This is the alternator on a L-18 engine in one of my project 521 trucks.   This alternator came out of a Nissan Pathfinder, Pathfinders are real common in junkyards in the USA.   I do not know what Nissan calls Pathfinders outside of the USA.

The L-16 engine in a 521 originally came with a stamped steel lower mount, held with M8-1.25 bolts,  If you have the stamped steel mount, your alternator fit may be different.

 
This shows the bottom alternator mount.  The mount is the same width as the space between the mounting ears of the alternator, and more importantly holds the alternator in the correct forward and back position for the V-belt grooves to line up properly.

 
This is the top mount for the alternator.  The slot for the top mount actually matches the radius the top mount bolt moves in.

 
A better view of the top mount.

 
This shows the view looking down on the belt, in pretty good alignment.

[wayno]

I have a couple of the lower ones in the photo below that Dmike posted, but I thought I got them off the Z22 block, anyway I was able to use the larger alternator with that lower alt mount and not hit the water outlet above.

 

 

I actually made a mount myself and the when I changed to the lower mount I noticed that 1 of my mount bolts had broke off in the block, so I will be removing the block in the next few months and will extract that broken off bolt so I can use all 3 mount bolts.

[mainer311]

With the 60A alternator swap, I ran 6awg wires for both power and ground. Something I found with old Datsuns, the more grounds, the better. It’s also highly suggested to run a fuse/fusible link inline on the power side.

 

The alternator I bought that fits like a glove is a Remy 14118, from Rock Auto. It’s a remanufactured Hitachi. There is a small interference with the top adjuster and a fillet on the aluminum case right where the upper flange meets the case. I filed the fillet with a rat tail file and that was it.

 

The belt is either a 15350 or a 15355. I forget which one I used. I can look in the morning.

[datzenmike]

The two mounts I posted could be backwards description wayno. It was probably 20 years ago.