97 Miata - Alternator Belt Change Issue

I've changed many belts before although none with manual tensioners. I replaced my belts because they were worn and I got the Powersteering belt And the alternator belt. I got them both on without that much difficulty. The issue I'm now having is with the tension in the alternator belt.

The PS belt is nice and taunt with just a bit of deflection. I did the same for the alternator belt. Start it up and the squeal can be heard a mile away. I get under the car, loosen the alt mount bolt and mess with the adjuster and loosen it, while still not being super lose. Still squeals. I currently have it loosened to the exact point of where if I tightened the tensioner bolt anymore and then tighten the alt mount bolt it would squeal, yes I did it while the car was running. But the belt looks absurdly loose and Def more than when I took it off. I mean it ran for 10 minutes fine but It looks wobbly as it goes around the pulleys. I know it's the alternator belt squealing because when it was doing it, even after running it just for 10 seconds, the belt is hot to the touch and so is the bolt of the Alt pulley.

Right now it is set with no squeal but the alt belt is about 5 times looser than the power steering belt that doesn't squeal at all. I'm at a loss of what to do. And we have autox Sunday.

Thanks all

Alternator bearing, if the hub is getting hot…..I have one in the shop squealing like that right now.

I'm confused ... Are you making the alternator belt right when the engine is off? Can you spin the alternator pulley easily without the belt on? is the tensioner the type that you loosen (turn counter clockwise ) the bolt to extend the alternator and make the belt tight ?

I adjusted it with the engine off, but it's such a minute point where it squeals or not that I adjusted it with the engine running for the final adjustment for the day (had to Go to work). There is the alternator bolt underneath and behind the alternator that is loosened so the tensioner bolt can actually tension the belt by pulling or pushing the bolt that is on the top of the alternator.

Alternator spun easily when the belt was off.

It is not a typical tensioner that you just put a wrench on and push on to loosen the belt. It's a threaded bolt that does it and then you tighten the actual bolt that mounts it.

I read about the bearing but it not like birds chirping but a terrible constant squeal when it is tightened like the PS.

I mean, the belt cannot be moved off the pulleys how it now, I cannot pull on it and slip it off. So it at least has that much tension. Is there any reason it would "fall off" from normal engine load? Like if I left it how it is and when for a ride? I know it's also the water belt pump belt as well so if it failed, but I think I would lose electric power before the lack of water pump turning would cause overheating.

I always loosened the alternator bracket bolts above and below. Use tensioner bolt to tighten belt. Make belt tight . Re tighten up all boots. Check belt. Re tighten if needed. I think it should be fairly tight. Like only a 1/2 of deflection if you press hard on longest part of belt . If it makes noise with belt tight it's maybe a bearing as mentioned.

So if it's a bearing do I just buy a new alternator and replace (not hard to do)? Kinda sucks though if I have to do that

I have found once you have squeaked a belt they are more prone to continue to squeak.

I've also found this helpful - http://www.miata.net/garage/KnowYourCar/S9_Belt.html

I put a new belt on.
I used that instructions page but the Nb guide shows exact pictures that match since I have the 1.8. But the belts are already replaced and on. The issue is why is it squeezing when it's not over tightened.

Quote:

---

Originally Posted by Yamahaman444

So if it's a bearing do I just buy a new alternator and replace (not hard to do)? Kinda sucks though if I have to do that

---

You could disassemble the alternator and source a replacement bearing or bearings and get them replaced. I've never done it on a miata although I have done it on other vehicles.

Started her up, I don't think the tension I have it at is too loose, but after a minute of running, the alternator belt is slightly warm where the ridges are and the alternator front nut is hot. But there is no noise. No chirp chirp chirp. No anything. I guess an alternator has to be replaced at least once in a cars life??
I did not check either of these things before changing it. So I don't know if it was doing it before.

All I know is something was squealing when I would drive normally for about 20 minutes, but only under engine load. Come to a stop and no squeals. So I figured belts. I need more people's input, or someone with a 1.8, go idle your car for a minute or two and then touch the pulley nut on the alternator and see it its hot. Please. I will replace my alternator tomorrow If all else fails.

Before you go ahead and replace the alternator, can you post a picture of your setup right now at the alternator pulley? These are the few things I would check.
1. Ensure the pulley is not misaligned somehow.
2. Look at the inside of the new belt to make sure it's not glazed over.
3. Does the belt look like it's riding on the pulley at the right height?

If you don't have the proper tension at the belt it might be slipping and causing the pulley to heat up, however if you have a squeal at the right tension, something else is wrong with the alternator or it's pulley somehow, bad bearings, belt misalignment issues maybe? A video of the belt and alternator with the engine started with a few sharp revs would be even better.

Does the belt fit into the groove on the pulley, or is it riding on top?

It is in the grooves. How it is tensioned now makes no squeals even with sharp throttle inputs but the pulley is still getting hot. I can post a picture although I've never done it here. I had business to attend to and I won't be home till 11. The problem is I work today and tomorrow from 2 to 10 so I don't have time for all this. I have a local alternator shop that will redo the bearing for 45. New one is 135.

Belt is not glazed, it's riding in the grooves. I can tell when I view it from underneath it it seated properly. It looks how it did before I replaced it, except now it's a new belt.

Don't have a YouTube channel so can't post video.

Right now there is no squeal, but it's much looser than the Ps belt and the alternator pulley is still heating up. And yall say that's not normal.

Also the pulley grooves are clean, no old belt rubber in them.

Belt is not glazed, it's riding in the grooves. I can tell when I view it from underneath it it seated properly. It looks how it did before I replaced it, except now it's a new belt.

Don't have a YouTube channel so can't post video.

Right now there is no squeal, but it's much looser than the Ps belt and the alternator pulley is still heating up. And yall say that's not normal.

Also the pulley grooves are clean, no old belt rubber in them.

Take the belt off, push down and turn the pulley, feel for any bad spots in the bearing. It should be completely smooth.

Check with Rogue if you need an alternator before you buy a new one. He may have one.

I can turn the pulley and it's smooth. The pulley isn't super easy to turn but I don't think it's supposed to turn freely? It rotates just fine though

IDK what the issue is, but just wanted to stop in and say the stock alternator bracket is a piece of junk. Good luck.

The bottom bolt that holds the alternator on is too long to be able to remove it from the holed. It hits the engine bay frame or sub Frame. Or. Something before I can back it all the way out. Can't remove the alternator if I can't remove the mounting bolt. None of this should be that difficult.

Put it all back together, now it's chirping, I took that back bracket off so I can remove the alternator. Going to the place now.

Alternator is out. Spins perfectly freely with no issues or noise. I'm really at a loss. I just wanna race sunday

Alternator is fine according to the starter and alternator shop. He suggested my battery isn't holding as much power as it should which could cause the alternator pulley to slip or something. I don't have issues starting it or anything, it always cranks over. I guess I'll tackle that tomorrow. If anyone wants to drive up to Argyle tomorrow morning I'll buy you beer and steak. I really don't know what the issue is

Put it all back together. Same thing as first post. Seriously someone PM if you're free To help tomorrow morning.

Have you tried it with both your new and old belt? Is the pulley alignment good? What kinda belt do you have for a replacement.

I'd hop by to look at it, but I'm out of Dallas at the moment. :(

Whelp, I guess I had it tight enough to squeal but not enough to have proper tension. I tightened the crap out it. It runs fine now. No squeal. No heat. Way tighter than I thought it should be but that was the last thing to try after reading online. Feel kinda foolish but hey, I didn't know it should be that tight. Anyways, thanks all. There's no heat at the bearing or the belt now.

Good work!

Good to know it's a simple fix. :)

Quote:

---

Originally Posted by Yamahaman444

Whelp, I guess I had it tight enough to squeal but not enough to have proper tension. I tightened the crap out it. It runs fine now. No squeal. No heat. Way tighter than I thought it should be but that was the last thing to try after reading online. Feel kinda foolish but hey, I didn't know it should be that tight. Anyways, thanks all. There's no heat at the bearing or the belt now.

---

Dang ,now I wish I would've taken you up on the steak and beer offer