voltage regulator dead, again

[scottlanes]

I have a 68 satellite with a 318 and I recently (6-8 weeks ago) replaced a mechanical voltage regulator that failed with a solid state version of the same stock type.

Last night in noticed that the voltage was dropping below 10 volts, down to almost 8 at idle and spiking up around 16 volts when i rev up to like 3K. The low voltage at idle makes the idle rough and the radio shuts off until i rev it back up and the voltage comes back up. The voltage reading is according to the aftermarket voltmeter on my dash, my tach is also jumpy at idle, the same symptoms that made me replace the regulator in the first place. The voltage seems correct at the battery (14.5 volts even when revving) and the same at the alternator measured with a volt meter.

I checked the ground for the VR and everything seems fine there.

Does this sound like a VR issue again or am i missing something. With the voltage wavering like that I couldnt help think it was the VR. The drop does not seem related to headlights or any other load.

thanks in advance for any help....

-scott

 

[74sundance]

Have you checked the Alt belt? Could be slipping,what are your RPM'S at idle?

Check the 2 field wires that connect to the back of the Alt they almost always need to be replaced.

What Tach are you using,and what wire did you tap it into?

If you have your green Tach wire connected to the (-) coil it will be jumpy, you need to tap the Green signal wire from the tach into the Gray wire to the ignition box (assuming your running a stock chrome or orange box)

 

[scottlanes]

Have you checked the Alt belt? Could be slipping,what are your RPM'S at idle?)

nope, belts and alternator are fine, it idles at about 600 and up until last night has been running at just about 12v at idle with little to no headlight dimming at night

The alternator is a newer 2 field and im wondering if maybe the higher amps are what killed the stock VR

Check the 2 field wires that connect to the back of the Alt they almost always need to be replaced.

Already cleaned up the connectors and that seems to be ok

tap the Green signal wire from the tach into the Gray wire to the ignition box (assuming your running a stock chrome or orange box)

Points, so no ignition box, its off the coil, but it is usually solid. Its an autometer tach

 

[69 Runner]

You aren't using one of those "blue" ones that M.P. says you "have to use" with an electronic ignition are you?

 

[scottlanes]

You aren't using one of those "blue" ones that M.P. says you "have to use" with an electronic ignition are you?

you must mean the constant voltage one, no, I saw your post in another thread and avoided that one. The Autozone near me is getting me another on of the VR706 ones (the same one i currently have). I'll put it in and see what happens.

I tried converting over to the newer VR as described here:

http://www.moparmusclemagazine.com/...regulator_and_alternator/charging_system.html

but I wasnt able to get it to work. No matter what I tried I couldnt get it to charge, it hung there at like 8 volts. So back to the old style one. I'm hoping that the issue I am having is really just a VR issue, but I dont know why the VR I put on a couple months ago is dead already.


While researching today I came across this article, so I think I'm going to do this as well. Not that its directly related, but it makes sense to do:

http://www.madelectrical.com/electricaltech/amp-gauges.shtml


-scott

 

[69 Runner]

The new regulator (in the first link) should function fine. I've never had an issue with one. But it not working either means 1) that new part was bad out of the box, or 2) there is a problem with the wiring/alternator/etc. So you haven't found your problem yet. Personally, before I did some newwave updating on the system, I'd work to make it work "as advertised" first. That may mean replacing harnesses. Made a world of difference on my Duster.

 

[scottlanes]

Ya, I'm hoping i got a bad VR. I dont have the cash to start replacing harnesses at this point, as much as I would like to do that. I was thinking of redoing the main wiring as described in the above link because I thought maybe there was something in the wiring that was creating a bunch of resistance and may have cooked the current VR. I was thinking about corrosion in the firewall connector, maybe the amp meter?

Its my daily driver so i have to try to keep it going

 

[scottlanes]

well it wasnt the VR. I'm going to take a closer look at the alternator i guess....

 

[74sundance]

I think your charging system is fine but your Idle RPMS are to low...All engines require an acceptable air/fuel ratio to run properly,even at idle. Stock or mildly tweaked engines generally idle at 16-18 inches of intake manifold vacuum between 750 and 900 rpm...
What happens when you put it in gear and hold the break? How low do the RPMS drop then? I can't remember the normal stock idle RPMS for your motor but I think its between 800-900 RPMS If I'm rite your alt can't keep up at idle and then gives full output when reved up to try and top up the batt.

 

[74sundance]

One other thought is that if your new Alt has a different size pulley it could be that the Alt is not turning fast enough to give max output at idle.
Typically, a street driven car should have a pulley ratio of at least 3:1. If the car has an automatic transmission with a low idle and you spend a lot of time cruising, then a higher pulley ratio like 3.5:1 should be used. Alternators can take high speeds up to 20,000 RPMs for short periods, so overdriving the unit is not a problem.But under driving will not make the power needed.

 

[69 Runner]

The performance cars back then had a rather large pulley on the alternator to "underdrive" it because these cars were expected to see a lot of WOT and high RPM's. However, most of the alternators available today don't have a large single groove pulley. They usually come with a smaller diameter, double groove pullet like what a lo-po or A/C equipped car would have.

 

[scottlanes]

it does have a pretty small pulley. I'm going to see if i can round up another alternator and see if its the alternator. It may be a slow idle issue but it seems strange that its been fine at that rpm and all of a sudden it isnt pumping out enough juice. Eh, i'll find out, in the mean time i'll up the idle a couple hundred rpm.



-scott

 

[69 Runner]

The smaller pulley was a (kinda) fix for the low voltage at idle

 

[74sundance]

The smaller pulley was a (kinda) fix for the low voltage at idle

yep

 

[scottlanes]

I ordered this from summit, will be here tomorrow, i'll let you know how it goes....


http://www.summitracing.com/parts/T...925143+4294880793+4294908110+115&autoview=sku

 

[scottlanes]

ok, just bolted the new tuff stuff alternator in and it fixed the idle low voltage issue.

The alternator itself is rebuilt, and it is a very very nicely rebuilt item. I got the powder coated black one. The powder coating looks good but is more fragile that i thought it would be and already had a few chips around the screws and on some corners. I dont care so much, it works great

So I'm back to where I was before, 13-14 volts at about 6-700 rpm, idle is perfect again

 

[74sundance]

Cool,glad to see you up and running.....Now swing on by and lets take her for a rip!!!