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How to test voltage regulator (not running)
Posted by: lgoodwin ()
Date: May 12, 2011 02:55AM

I want to know if there are any basic tests that I can run on my external voltage regulator (62 Monza) WITHOUT RUNNING THE ENGINE to eliminate the V/R as a possible cause of this odd problem? I have an analog volt/ohm meter.

It was starting just fine for a long time every time I've been working on the car. I kept the battery stored indoors when not using it and it still looks like new.

More recently, the starter would crank fine for several tries, then start having problems, and now I cannot get it to crank at all now.

Now, the problem has gotten worse to the point where it would not crank at all the last two times I tried to start the car.

I recently had the battery quick-charged and load tested and it tested good.
I just checked the voltage across the battery terminals again, and it reads 12 volts, so I don't think the battery is the bad.

Have replaced the starter during the time in which it would crank fine the first few/several times (both old and replacement starters). Have already checked and cleaned the battery terminals, battery cables (both ends), battery ground to chassis and starter cables. Before that, I replaced the generator. I was startable with both generators (the gen light stopped coming on after installing the other generator).

The voltage regulator is out of the car and looks like new inside. What can I do to test this unit by itself?

Thanks!

1962 Corvair 900 sedan1967 Corvair Monza 140/4-speed1968 Corvair 500 coupe1983 Mexican Mustang 5.0
1962 900 sedan needs a home1967 Monza 140/4-spd1968 500 coupe (now my son's)1983 Mexican Mustang 5.0

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Re: How to test voltage regulator (not running)
Posted by: Chris Lampe ()
Date: May 12, 2011 03:30AM

Luke,

I think your battery maybe bad. A good battery should measure 12.8v with no load on it.

There is a detailed test procedure in the service manual to test the regulator, from what I remember you disconnect one line at a time from the regulator and make a voltage or current measurement, but all these measurements are made with the regulator in the car with the car running. I realize this is not much help to you if you can't start the car.

Chris
Rowlett, Tx
NTCA - North Texas Corvair Association
CORSA
'64 Monza 'vert

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Re: How to test voltage regulator (not running)
Posted by: MattNall ()
Date: May 12, 2011 03:31AM

Luke.. you need several pieces of equipment you don't have...


Did you ever jump the car?





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Re: How to test voltage regulator (not running)
Posted by: cnicol ()
Date: May 12, 2011 03:51AM

The only way I know to test a VR is on the car, running, with the battery tested and charged.

The battery/VR/Generator are all co-dependent and symptoms usually don't point to any particular one. Sometimes, two of the three have problems which really makes it fun.

Here's how to shake out the culprit:

1) Charge and test the battery (as you have done)

2) Put a voltmeter on the battery (should be 12.8 volts for a fully charged battery)

3) Start the engine. If the engine won't crank, clean the battery terminals and retest. Still no crank; check the cranking voltage, first at the battery posts (actual posts, not cable ends), then at the starter lug. If the voltage goes very low right away (10v or so), the battery is bad regardless of what the prior test said. If the voltage at the battery stays good but is low at the starter lug, you have a bad cable. If it never really spins well even at the start of cranking, the starter is bad or the engine is tight.

4) Once started, check the voltage at the battery. It should be 13.5-14.5v after a minute or two at high idle (1500). If if doesn't come up to that range, you need to sort out if it's the generator or the regulator.

5) Assuming the battery voltage stays below that range, while still at high idle, temporarily short the F terminal to ground and observe the battery voltage. If it slowly goes up the the right range or higher, the generator is working and the VR is faulty. If the voltage doesn't go up, the generator needs repair.

Hope that helps.

Oh, one other thing... The generator and regulator aren't part of the "poor cranking" issue. You either have a bad battery, bad starter, bad cable, or bad connection. Again, the generator and VR are not part of the picture, only the items listed are involved.

Craig N. Coeur d'Alene ID.
66 Black Monza 4dr, 4.2L V8 49k
66 Red Monza 2dr 140/4 EFI 60k
61 Seamist Jade Rampside 140 PG
65 Cypress Green Monza 140/4 4dr
65 White 4-dr 110/AC/PG (parts)



19 Tons of parts in boxes

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Re: How to test voltage regulator (not running)
Posted by: cnicol ()
Date: May 12, 2011 04:01AM

Probably is the battery or starter, but let me share a story... When I went to Denver to pick up the stinger I drove my pickup and towed a box trailer. On the way home - nice sunny middle of the day - I heard a loud humming noise. I pulled over and the engine died; smoke came out the edge of the hood. Opening the hood, it was obvious that the alternator had died - it was what was smoking.

I thought about driving to the next off ramp and tried to start the truck. All I got was "clunk" "clunk" as I tried the key. It sounded like I had a bad starter. Actually, the seized alternator was preventing the engine from turning.

I unloaded my spare car (hahaha) and drove it to purchase another alternator. I'm not saying this is your problem but do verify that the engine turns over easily...winking smiley

Craig N. Coeur d'Alene ID.
66 Black Monza 4dr, 4.2L V8 49k
66 Red Monza 2dr 140/4 EFI 60k
61 Seamist Jade Rampside 140 PG
65 Cypress Green Monza 140/4 4dr
65 White 4-dr 110/AC/PG (parts)



19 Tons of parts in boxes

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Re: How to test voltage regulator (not running)
Posted by: lgoodwin ()
Date: May 12, 2011 04:14AM

Matt, I have not tried jumping the car, as I cannot jump that high! Hah-ha!
But seriously, thanks for the suggestions guys.

I don't have another battery here that can be used in this car. I could try jumping it using my truck. If it cranks fine jumped, I'll have the battery tested AGAIN, even though I just had it tested at AutoZone. Also need to check battery cells.

I was hoping to test the V/R for an open or short condition that indicates a problem with it. I know the V/R is not supposed to be involved in starting the car, but I thought an open or short in the V/R might possibly interfere.

1962 Corvair 900 sedan1967 Corvair Monza 140/4-speed1968 Corvair 500 coupe1983 Mexican Mustang 5.0
1962 900 sedan needs a home1967 Monza 140/4-spd1968 500 coupe (now my son's)1983 Mexican Mustang 5.0

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