Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

Alternator Pulley Inconsistent Spin (is this a sure sign of a bad alternator?)


So the alternator belt on my kia rio broke I made a post and got some good responses about what to do and decided I would replace all 3 drive belts (good thing too as the AC belt looked SUPER worn on bottom). Anyways as I’m doing this I decided to check the alternator pulley (I had done so previously and thought it was fine) and actually noticed that it didn’t spin as smoothly as I originally thought. It’ll spin easy for maybe a 1/2 to 2 rotations and then it’ll have some resistance and repeat. I do think the belt was super old and worn and that was the main reason for it breaking but this could also be a contributing factor and I already suspected the alternator (really i suspected a weak battery until recently tbh) I was having issues as I frequently had to jump start my car and when the belt broke it wouldn’t start back up. I’m checking on here to for sure know if I should replace it or not I called and checked and it would be about $200. Just wanting a second opinion before I commit.

The alternator should spin freely.


1 Like

If you can remove the alt and take it to an auto electric shop they can probably fix it reliably and at moderate cost.

We have a couple electric shops around here that do this kind of work, but they don’t just work on automotive electronic parts. They’ll rewire automotive alternators and starters…and they’ll also rewire your hand drill. Anything electrical.

What I’m REALLY curious of is if I should try the alternator as is and see what happens or could that cause damage(like break the belt again) or if I should definitely just go ahead and replace it.

From what you describe, it sounds the bearing in the alternator is failing.

So yes!



BTW, has anyone ever replaced the front bearing in an alternator when it was beginning to seize. Once was enough for me. The armature and or the front housing are likely galled enough to quickly cause the new bearing to fail. Rebuilders apparently have tricks to correct such problems.

$200 for an installed alternator for this car seems extremely inexpensive. I wonder if it is from a junk car.

Ah sorry thats just how much the alternator would cost I was gonna replace it myself.