[Dana W]

I have a 1999 Suburban, K1500, 5.7 TBI. Lately my voltmeter has been dropping from around 14 V down to about 12 or less. I could see it move, then a few minutes later, it will visibly move back up to 14. When the meter is reading low, I can turn off something, like the heater blower, and it will go up a bit, but not all the way up. When it is reading max charge, turning high load stuff on and off has no effect on the voltmeter.

And then today, when I cold started it at home for the first time today, it did seem a little weak. The starter turned over slow before the engine caught. I drove it a half mile to the store, and it would not start when I wanted to go back home. There was not even a solenoid click. The battery still had enough power to lock and unlock the doors, and roll two windows up that I had left down, but it would not start without a jump. After jumping it, I drove it the half mile back home with the voltmeter sitting on the 14 V mark.

I suspect the battery is not being charged properly, the battery is almost brand new.

The alternator is an internal fan type, 6 groove pulley. Can it merely be the regulator pack? Is the regulator even replaceable on this type of alternator, or do I have to spring for the whole alternator?

If anyone has any other ideas, I would be happy to hear them.

 

[RayVoy]

It could be the alternator, or the battery. You can get both tested at a parts store

 

[silverado002]

I vote for the alternator as I don't think a battery will fluctuate voltage like that unless there is a connection problem with the wiring.

 

[poncho62]

Check the belt also...it may just be slipping and not turning the alternator fast enough

 

[Philspad]

I've been through this several times.
First,
Do you have the twin battery towing package?
If not, I probably can't help you.
If so,
Check all battery connections.
Seriously, If you try to move them with your hand and they do.... There is your problem.
With the vehicle off, and you get 12-13 volts across the terminals, You might still have a bad cell in one of your batteries.
Take it to parts store and have them check each one individually.
I know it sound asinine..... but take the batteries loose from all cables then check them.
Hope it works out cheap for you!

 

[Chesters]

I've been through this several times.
First,
Do you have the twin battery towing package?
If not, I probably can't help you.
If so,
Check all battery connections.
Seriously, If you try to move them with your hand and they do.... There is your problem.
With the vehicle off, and you get 12-13 volts across the terminals, You might still have a bad cell in one of your batteries.
Take it to parts store and have them check each one individually.
I know it sound asinine..... but take the batteries loose from all cables then check them.
Hope it works out cheap for you!

Hi Phil welcome to the GMTC , thanks for kicking in, that's how this thing works

 

[Dana W]

Thanks guys. Good info. I guess it's time to take it through the testing steps.

It's not the weather, I'm in central Florida. It was nearly 80 yesterday afternoon, and almost 7o here at 10 AM.

Single battery, factory towing package. Almost new belt, almost new idler pulley. There has been no slippage noise that I can detect, nor any visible damage to anything.

Just before the No Start yesterday, I had cleaned the battery posts, and made sure they were snug, because it had been doing slow cranks when started hot, for a week or so.

This morning the truck cold started well, and the voltmeter ran up to max right away, so the battery was able to "rest" overnight, and build a charge back up by itself. This issue is by no means solved by that evidence, but I think the battery is OK. Like I said, the battery is only a month old, warranty replaced then.

After starting it this morning, I turned both heater fans to full blast, lights all on, A/C on, and radio on. The Voltmeter dropped a few under that load, but only a couple ticks, so the alternator is acting relatively normal too, for now. I then turned everything off, and the voltmeter came to rest just above the 12V mark. My multi-meter says the battery has 12.3 volts, so it is not fully charged right now, shouldn't it read over 13? I know it is the amperage generated by the charge that is needed, so the voltage reading is only an indicator that the charge "is probably" a little weak.

My next move is to pull the alternator and get it tested. The way that will work, is that the intermittent problem will not show up under testing, right?

Thanks everyone. I will let you all know what I find.

 

[Chesters]

Just take the truck to Autozone and have them test the system, they can tell u what part is bad.

It's free

 

[Dana W]

That is the ultimate solution, of course. We're just running through the symptoms at this point for future reference.

 

[Dana W]

Seems my issue is resolved, at least for now.

When I said "almost new idler pulley" above, I meant "Almost new belt tensioner assy & pulley", which brings me to the point of this post.

Go get a beer and then start reading. I am not a man of few words. I like to make sure that everyone understands me.

Over the past couple of weeks, I had occasionally heard an intermittent, but not loud "wahggnnuuuuunngh" noise. Also I had noticed that the idle speed @ oper. temp. was not up to where is should be. It hovered around 450 to 500 rpm. Those oem gauges are really hard to read with the needle in the way. I figured the TB needed a bath, and had planned on doing just that yesterday before I had the "no start" issue at the store.

Anyway, this morning while I was contemplating how to get those split compressible bushings to release their hold on my alternator, considering a small pry bar, I nonchalantly put my hand on the idler pulley, and met much resistance. The danged bearing was nearly seized. I could barely turn the thing, and at points it would get much worse. So, I replaced the idler pulley, buttoned the alternator back up, and reconnected the battery. As they say, only change one thing at a time. Well, I did wire brush every connector, including the hot wire to the alternator before reconnecting them even though they were all clean.

I got in the truck to test start it since it had been long enough for the nearly new battery to once again self charge a little bit, The thing started stronger than it has in several months, like a new car.

I surmise that the idler pulley was sucking up 10 bhp at least, if not more. Not only was it making things more difficult to start the engine, but at every idle speed situation, like at every traffic light, the rpm must have been dropping below the charging threshold of the alternator. Everyone knows batteries discharge faster than they charge, so I guess I was slowly draining the thing to death. Even the huge 5.7 liter V8 in the Burb, has almost zero torque at idle speed, so any extra drag is way too much.

With the new idler pulley in, the voltmeter pretty much stays right on 14.5 to 15 volts, and does not move when I turn on every electric thing in the truck except the headlights, when it drops about a volt with the brights on, everything else is still on when that happens.

So, the alternator is charging at idle now, which it apparently was not doing before. Once the battery gets charged back to full, the meter should come down a little. The tach sits at about 775 to 850 rpm at oper temp idle, also.

The good part of this is, the idler pulley only cost me $18.00 plus tax, and I got a free upgraded "Florida Rated" battery a month or so ago because the seller/factory already had decided that their product would not last long in the far southeastern part of the country, and didn't even question me when I brought their "standard" one back because it went dead two years early. It was probably my poor charging condition that killed that one.

Sometimes you are the hammer, sometimes the nail.

Moral... The idler pulley only costs about 20 to 30 bucks at the most. Replace it, and maybe the tensioner too, when you replace the serpentine belt.

 

[RayVoy]

Thanks for the update Dana

 

[silverado002]

Abnormal sounds like you described need to be investigated ASAP. Good job finding that.

 

[Dana W]

Abnormal sounds like you described need to be investigated ASAP. Good job finding that.

Yep, I was "investigating" the noise since about a month ago, but the only time it would do it was right before my wife says "There's that new noise again.", and then it would stop, until just before the next time she said it. ROFL.

We've all heard that noise that a dry worn out rusty bushing makes on a kid's wagon wheel, kind of a squawk? Did I just date myself? Well, I only heard this noise once yesterday, and it only lasted for about 3 seconds. Apparently my wife heard it about thirty times. It was very low and muted, like a 500 lb toy wagon wheel under 10 mattresses. I would not swear the idler pulley was the source of the noise in court, but it most probably was. We'll know in the morning as I start backing out of the driveway. If I get to the street before my wife says "There's that new noise again.", then we're all good.

I swear I don't know how she could hear it over the roar of all the "old" noises. Every door, lock rod, and plastic panel in that old Burb either squeaks or rattles. Shift your weight in the seat and it sounds like mashin' a piglet.

The Burb has 140.000 miles on it, but the tranny and engine were replaced about 16,000 miles ago due to a deer accident, before I bought it from a friend. Don't ask me how a deer can take out a tranny and engine, but it did. At least don't ask me right now. I'll tell you later, I'm getting sleepy.

The transmission was brand new. Apparently the new engine (Jasper) didn't come with any of the outside parts, and now they are falling apart one at a time.

 

[thegawd]

cant wait to hear the deer story! not now though, i to am gettin sleepy LOL.

Al

 

[Dana W]

Thanks for the update Dana

Not a prob. Updates are what keeps us from re-inventing the wheel, and repeating everyone elses mistakes.