bigboy0723

I upgraded my 94 ES300 alternator 2 days ago to a 130 amp alternator. I bought the alternator from an used part store. The alternator squeals on start up. It goes away in a few seconds, or if i stop and restart the car, the squeal stps too. This only happens on the first start and any subsequent starts go away. At first, I thought the belt is too tight, so, I loosen it a bit. It helps a bit, it squeals less and pitch is lower. Do I need to adjust more?

Also, the alternator could be in the store for a while, not sure if the bearing needs some lubrication. It's pulley is also a bit rusted, I googled and someone said it might cause the belt skid on the initial start, not sure if this could be possible.

Thanks advance for any advice.

Oro

If it squeals, you should tighten it.

Google about how to tighten it; you can measure defelection at the mid-length of the run as a guide. I go for about 3/8" deflection. Another test is to try to twist it 90 degrees; if you can do that easily, it's too loose.

Sometimes, a belt will wear-in and a new component needs a new belt to be squeak-free. Did you change the belt, too? The bearings on the shaft of the alternator are sealed; you can not lube them.

LeX2K

If not the belt it could be the brushes vibrating they tend to do that when worn down. It could also be bearings with grease that is drying out.

mmatheny

Or the pulley on the alternator could be polished - take the belt off and hit it with a course metal brush.

HomerJay

As earlier suggested try a new belt and make sure the pulley is clean. You can spray a little brake cleaner and use a toothbrush if the grooves look a bit grimy. Do not use a course metal brush which is too aggressive.

bigboy0723

Thank you everyone for all the inputs. I re-tighten the alternator belt and the problem disappear.

Before the re-tightening, when I turned the rear defogger on, the alternator squealed and the voltage dropped from 13.8v to 12.3v, it stayed for a bout 5 sec, then jumped back up to 13.xx. After the re-tightening, the voltage stayed around 13.5v.

I drove the car this evening for about 2 hours both city and highway and didn't hear any strange sound with defogger on and off . I think the problem is fixed. Just need to wait till tomorrow morning to try the morning start. I am keeping my finger crossed.

DRACO A5OG

I would change the belt, it is trying to tell you to change it. But if it is only the belt a little spritz of WD40 will quiet it down to nothing.

bigboy0723

Thanks Draco. I examined the belt prior to my installation. There is no cracks and the belt ribs all look fine. If it still squeal, I will replace it. I am keeping my fingers crossed, hoping for the best.

DRACO A5OG

You should be fine :-). Just do not over tighten or it will kill the bearing. Ask me how I know. Lucky my alternator was warrantied.

bigboy0723

Have been driven the car all day. No more squeaky noise even on the morning start. I believe problem is solved. Thank you everyone for their inputs and suggestions. 😀

DRACO A5OG

Oh Congrats :-D