Bad Alternator ? Volt gauge periodically maxes out....

gladesteen

Original poster
Member
Aug 19, 2014
83
Hi gang,

I suspect the voltage regulator is shot in my alternator. For the past few days, i've seen the volt meter gauge on dash almost maxed out for no apparent reason.

Tested battery, its good.
Put key in RUN position -- volts are normal on dash
Started car, have seen the voltage rise to almost max for no reason. Other times, it sits perfect in dead center.
The volt gauge always goes back to "home" position when key turned off........so i dont suspect stepper motor.

Thoughts?

2004 Olds Bravada - 150 amp
 

m.mcmillen

Member
Apr 29, 2016
554
Wisconsin
I would check the voltage with a volt meter when the gauge spikes. If your meter correlates with the dash gauge, get an alternator.
 

gladesteen

Original poster
Member
Aug 19, 2014
83
thanks, i was going to do that anyway. Its pouring out right now tho...hahaa.
Have to wait until it fails to the max/high side to test.

Question: is it "bad" to drive around with the alt pushing max volts like that? I dont want to burn up anything electrical, etc.

Just ordered a new AC Delco alternator on Amazon for $143........not bad!

From what i gather, its either the Alt or the PCM. Hoping alternator........
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
Check your battery connections. If good, then yes,you could cook the battery or burn out something but at 15v, you should be OK.
 
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gladesteen

Original poster
Member
Aug 19, 2014
83
Hi all.......just wanted to follow up on this as many dont close it out.
I tested the battery cables off/on ignition and start / run modes and everything was fine.
Pulled the pos and neg cables off battery........the postive had very, very, small amt of corrosion. So i hit it with a brush and cleaned up. Next i sprayed the alternator coils with half a can of brake clean thru the vent holes..........havent had another full volt incident since!

WoW ! I have the new alternator just in case, but may end up returning.
 

mrrsm

Lifetime VIP Donor
Supporting Donor
Member
Oct 22, 2015
7,639
Tampa Bay Area
Congratulations on this repair ...and for having the perspicacity to provide a “The End” to The Story! However for anyone following along… instead of using Brake Cleaner Solvent, which may dissolve some of the Clear Lacquer Insulation Dip that rigidly secures the Copper Coils in their twisted bundle inside of the Alternator and prevents Internal Coil Shorts… CRC makes a purpose-specific “Lectra-Motive” Electrical Spray Solvent that is a better choice for performing the Coil “Wash-Out”. Keep in mind that you want to avoid hitting the Front and Rear "sealed" Roller Bearings as their internal Grease can get dissolved and invite Alternator Bearing Failures as well. This stuff is available on Amazon for around $10.00 a Can:

https://www.amazon.com/dp/B000BXHWCA/?tag=gmtnation-20

CRCLECTRASOLVENT.jpg
 

gladesteen

Original poster
Member
Aug 19, 2014
83
Yes...…...good call on the CRC. I still think the alt is on its way out...….it might be a temp fix, we shall see. Still "whiny". I have the new AC Delco on hand and have plenty of return warranty time left.

I started seeing the high volts during really cold temps (NH), but lately we aren't too bad. When the temps were in teens/single digits is when I saw the spikes. I will check again and report back if it returns.
 
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mrrsm

Lifetime VIP Donor
Supporting Donor
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Oct 22, 2015
7,639
Tampa Bay Area
There is one last thing that may be necessary for you to inspect for Continuity, "Green" Cupric Oxide Infestation...or Internal Damage such as Separated Copper Wire Strands and Stretching UNDERNEATH the Insulation...and that is the Red Wire that Connects to the Alternator. You could find yourself right back in the same boat... if there are Hidden Problems as mentioned....and be well on your way to ruining the Brand New Alternator. Be fastidious and use a Very Bright Flashlight during your inspection.

You are looking for breaks in Continuity when hooked up to a Volt Meter...and Jiggling the Wire. If you see any Thinning of the Wire or Black Smudges on its exterior that do NOT rub off... then replace the Tinned Copper Eyelet Connectors and ONLY use Automotive Quality Wire(s) with the Proper AWG (American Wire Gauge) that presents High Durability and Resistance to Voltage up to 600 Volts along with the kind of non-slipping insulation that is Fire and Heat Resistant. THIS is likely the stuff you will want to get:

https://www.amazon.com/dp/B01M7NWX7A/?tag=gmtnation-20

awg16autowirebundle1.jpg

....or this...

https://www.amazon.com/dp/B01NBTRO24/?tag=gmtnation-20
 
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JayArr

Member
Sep 24, 2018
504
Mission BC Canada
You mentioned it's still whining...

You know you can add grease to that front bearing right?

Instead of waiting for it to self destruct, take the belt and pulley off, you don't have to remove the alternator. Once you can see the front of the bearing take a small fine screwdriver and pry the front cover off the bearing, this is the black or green or orange rubber ring that has the part number on it. It's just sitting in there as a dust seal, it's not bonded or fastened. You do have to be careful not to bend it too much since part of the seal/cover is metal, like a thin washer, that the rubber is attached to and avoid tearing the rubber. You need to put it back so go slow until you learn how it comes out.

Once the front cover is off clean as much of the old grease as you can with a clean cloth, if it's really dirty you can try spraying solvent in to help clean it out, then re-pack it with fresh grease and then pop the front cover back on the bearing and re-install the pulley and belt.

This also works great on the bearings inside the idler pulleys and anywhere else you can get at the face of a "sealed" bearing, I re-lube mine every year or so, it takes only a few minutes, costs virtually nothing and saves time and $$ replacing parts.

If you change the grease on a bearing regularly it could last forever, there is no reason for a properly lubricated bearing to wear out. I didn't know this for a long time, I thought that bearings had a lifespan and were only good for so many rotations then they needed replaceing. A friend of mine who works on Boeings explained the concept to me that as long as the lubrication is changed regularly and kept clean the bearing itself will never fail, they don't "wear out"
 
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