Chevy & GMC Vans

It might just be your tensioner that has gotten weak and is not applying proper tension on the belt.
Pick up a cricket gauge and check your belt tension. They are hard to find and you may get some blank stares at the parts counter, but they do exsist.
I know this may sound like a very wrong thing to do, but take a very small amout of sunlight dish soap and apply it to the belt, evenly. If the squealing stops after a period of time it would be my quess your tensioner needs replaceing.
Surpintine belts tighten as they get warm.
If it used to stop after a period of time and now it doesn't I would suspect the tensioner has failed to the point where it is unefective.
My guess is when you were in a turn the p/s pump was under load, it would take what ever slack was available and stop the squealing, now that the tensioner has wore out to the point where it cannot compensate even with that extra load of the p/s pump it is now unable to maintain proper tension and squeals all the time.
Peter

I would replace the belt and the tensioner pulley. The pulley is cheap and I have replaced mine 2 times in 330 000km.
The belt on my Honda Accord went at around 105,000km and it was squealing so badly I thought a bearing was gone on the tensioner or the AC.
I replaced the belt and it was fine. It is a fairly easy job and good piece of mind.
Rocke

take a look at the ribbed side of the belt, if the ribs are cracked it's close to done.
roughly 4 years is all they'll last. keep in mind if the serpentine belt goes, your done for the day.

Just what Kings X says.... > does your serpentine belt looked cracked on the inside?

Replace it....! Before it leaves you busted and stranded.... Don`t be cheap....!

I would be surprised if the pulleys were worn out. The two that need to be changed for sure are the tensioner and the idler pulley. Those two are a plastic material and I've seen them worn to almost nothing.

phr1$k37 wrote:
Oh I will replace! And with OEM belt. I will change the tension-pulley as well. Tonight I purposely cranked the steering wheel full left and right and sure enough the noise is minimized.
But I was curious - would it be worth while to put in performance pulleys?
BTW how long does it take to change the belt? It is cold out >.<

with a spring loaded idler pulley it just takes a few minutes to change. A long breaker bar and a socket to take the tension off the belt helps, but I"ve done it with a standard ratchet before...just takes more elbow grease.
route the belt around all the pulleys and do then do the idle pulley last - easier to slip the smooth side of the belt onto the pulley.
if your belt routing sticker is not still in the engine compartment, draw yourself a diagram of the belt routing before you start.

well at least your not guessing anymore.........sorry, i have nothing valuable to add.....hahahh...maybe my c-walkin' avatar will make things better.....i'm trying ok....what more do you want...hahaha

Use your digital volt meter to check battery voltage with the engine off. Then recheck with the engine running. You'll see whether the alternator is charging. You are looking for a voltage of between 13.6 and 14.2 for a properly charging alternator.

Some vehicles will run on the alternator, some won't. I don't know if the Astro is one of them. I have heard that disconnecting the battery while the engine is running can pop the ECM. I don't know if that's true but I wouldn't take a chance.