99 Suburban, 56K miles, alternator question

we have a 99 Chevy Suburban, K1500, approx. 56K miles. New battery & new belt, (recently).
From the alt., I'm noticing a weird whirring sound. Not loud, but it's noticable at idle
speed. When the engine is warm, and again at idle, I'm noticing the voltage is anywhere from 9 - 11 volts. When at cruising speed, sometimes the alt. will reach 13.5 - 14volts. But most of the time it stays around 12. As noted, I have a new battery and belt. (the alt. is not keeping the batt. charged...).
Is it typical for the alt. to start having probs with this amount of mileage?
Also, I noticed that the pulley tensioner doesn't really keep the belt "real tight". There's a little bit of flex. (I can push the belt in a little by finger tip pressure). Is the belt supposed to be super tight? I can pull on the pulley a little bit, and this will then make the belt super tight. But I can't keep it this tight, (unless you're supposed to torque the tensioner pulley). Is there a specified torque for the bolt that holds the pulley tensioner?
I guess worst case I'll run down and get a new alt.... Just curious if my problem is with the belt/tension, or if the alt. is trashed.
a couple weeks ago I took the alt. into AutoZone and they did their little test. Not sure if they can put an actual load on the alt. All they said (after a couple minutes), was that it was discharging proper voltage.
I took my battery back to Checker, and they replaced it free of charge with a new one. Still the same problem with the voltage readings.
TIA for your help.
-Gregg in AZ.
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The belt tension seems OK by your description, it's not supposed to be 'super tight'. Your alternator, on the other hand, is toast. Fortunately they are quite easy to replace.
Cheers - Jonathan
--
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Lieutenant Jonathan Race, EMS Supervisor
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RE/

When that happened to mine, I thought it was the trannie.
If it hasn't failed yet, I'd replace it ASAP - because you are not going to like the failure mode... ----------------------- PeteCresswell
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Sometimes an early failure is caused by jumping another car that had their own problems.

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<snip>
Yeah, I've gone through 2 of 'em and I have 91K on the clock. Just think, you're only about 20K miles away from a $2000 transmission overhaul not to mention all the other stuff that starts falling off when they get to be 5 yrs. old.
VLJ
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What parts fall off after 5 years? My '90 Suburban has 173,000 miles on it and I haven't had that problem. I went through several rebuilt alternators in a short time but after I stopped buying them at Advance Auto, the problem stopped (I bought an AC Delco rebuilt). I've found the truck to be very reliable and I frequently use it for long trips. I found out a long time ago that when it comes to mechanical devices, preventative maintenance is better than waiting till it breaks. I used to work on aircraft and you just can't pull over if you have a breakdown when you're in the air so regular maintenance is a must (it's the same with any vehicle). Lest you think I spend a lot of time working on my vehicles - I don't. They usually get maintenance at a time and place of my choosing.
****************************************** I would rather be exposed to the inconveniences attending too much liberty than to those attending too small a degree of it. ~ Thomas Jefferson ~
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<snip>

In my case:
AC compressor died (4 yrs. - 49,000 mi.) intake manifold leak (4 yrs. - 53,000 mi.) first alternator (4 yrs. - 54,000 mi.) second alternator (4 yrs. - 62,000 mi.) exhaust cracked in half & fell off (4 yrs. - 64,000 mi.) 4L60E transmission died (5 yrs. - 71,000 mi.) ball joints replaced (my choice - bladders tore) brake vaccuum boost unit failed (6 yrs. - 91,000 mi.)
not to mention:
wiper control board recall outside electric rear-view mirror switch fire recall
Have I replaced everything that can break? I doubt it. I'm selling it after its replacement shows up in a month and hope the fuel pump module and/or the Eaton limited-slip diffy don't blow up before its somebody else's problem.

Mine is an import - "Hecho en Mexico".

Indeed. I currently wrench 8 motorcycles, 3 cars, 1 lawnmower, 1 generator, 1 weedwhacker and sundry bicycles and have been doing all my own mechanical work since 1968 so I know preventative maintenance.
This particular vehicle, '97 K1500 Suburban, has simply been substandard compared to all the rest the machines I've worked on. Nothing I've ever owned before has cost me over $5000 in repairs or had such poor design that contributed to those failures and repairs. This has my has been my first and certainly is my last GM vehicle.
VLJ
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thanx everyone for posting your info. I have lurked around this group for a while. It's been very helpful to me, (for maintaining my 99 burb).
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I'm happy to say that I haven't experienced the problems that you two have. Maybe it's because my truck had 87,000 miles on it when I bought it and maybe because it was owned by a surveying company (and it had the mud packed in the frame to prove it). But if it makes you feel any better, I worked with two guys that only bought foreign cars and one spent $10,000 on his Porsche in 4 years for repairs while the other one put two engines into an Acura in a little over 3 years. Neither of them abused their cars, they were just unlucky.
****************************************** I would rather be exposed to the inconveniences attending too much liberty than to those attending too small a degree of it. ~ Thomas Jefferson ~
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RE/

This 'burb was my first new car and, I think, my last...
Used to sort of joke about the old card being mostly-debugged by the time I got them - just find out the immediate reason the peson was selling, fix it, and go...
Now I don't think there's something to it.
----------------------- PeteCresswell
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