voltage drop

Tonight when I went to leave Walmart. I took notice that my volt gauge dropped in my 96 Blazer LT while I was sitting in the parking lot. I had it in drive, headlights, heater were on and my foot was on the brake. The voltage was dropping(below 12 volts) but as soon as I hit the throttle it went back up to 14 volts. When I put it in park, still had the headlights and heater on it stays at 14 volts but as soon as I put my foot on the brake and put it in drive the voltage dropped again. In drive with my foot on the brake, if I turn off the headlights. The voltage goes up...

Also when I was going to Walmart tonight. At the one stop light when I slowed down and turned and hit the throttle again. The belt started to sqeal.

I was thinking it might be the belt tensioner since the belt was sqealing??


It just had a new alt put on about a year and a half ago when I bought the blazer. Battery I'm not sure when it was put in...

There is a chance that the alternator is on it's way out.
It doesn't cost much to get tested, and it's free at some places

Sounds like you need to replace the alternator and/or the belt.

My bet is the alternator is seizing up and causing the belt to squeal.

Get it fixed ASAP before it takes your belt out and leaves you stranded.

Thanks guys..

I just put a new belt on this past spring when the idler pulley went.

I'll go some where and get the alternator tested today.



Over the weekend I put in a new heater core,water pump and put on new heater,radiator hoses. When I took off the one heater hose. I think some antifreeze spilt onto the alternator. If antifreeze got into the alternator. Could that cause it to seize up?

I'm told that it eats the bearings in your motor up if it gets where it shouldn't so it's possible.

Update:

I went to take off the alternator about 2 hours ago to get it tested. When I did I took notice the belt wasn't tight enough. I put a 3/8 drive ratchet on the belt tensioner and pulled it up more. Then the belt was tight. So far it's now staying where it should be...

I started it up and the volt gauge went a little above 14 volts. I turned the headlights, heater, radio on and put my foot on the brake, put it in drive, the voltage stayed at 14 volts and didn't drop like it did last night.

When I put the belt on over the weekend, either I didn't put the belt tensioner up the whole way or else it's going bad. I still think the alternator might be going bad because when I start the blazer I can hear a noise which sounds like it might be the alternator bearings going bad.

Replace that tensioner first. It should keep the belt tight, and it might be the idler pully causing the noise.

I drove it last night and today for awhile. The volt gauge has been staying at 14 volts...

Hopefully it's not the idler pulley because I just put a new one on about 6 months ago.

Off the topic, but do you have any pic's of your Chevelle that you would care to share.

I recently helped a friend drop a 673 hp (we dyno'd it) stroker in one of those.
no pic's of his though I'm afraid

Your tensioner is going bad. The belt squeal, and voltage drop are all indicators of this. Change the tensoiner to get back the proper preload on the belt. This also wears your belt of faster too because if its slipping , your wearing it out, or if the tension is to much your stretching it, either way a new tensioner is needed.