I’ve gone through 4 belts in the past month so I decided to replace the alt on my s4 na when I noticed the alt pulley had excessive runout. I swapped to a built s5 alt that makes 160 amps. I put the washer spacers in the right spot on the back side of the water pump housing, and after a couple minutes of insane squealing the belt snapped while it was just at idle. I know it is not a tension issue as I made sure it is 1/4-1/2 inch of slack. What all could cause this? Also my water pump and e shaft pulley are def in the right spot as I have had zero problems with my air pump belt. I’m considering taking it to a mazda dealer to maybe see if they can diagnose/fix the problem however I’d rather not and I don’t even think they’d work on my car because of the mods.

 

I'd double check that the belts you purchased sat in the pulley groove correctly. If you are not using your smog pump I recommend the Banzai dual alternator pulley. They supply the kit with Gates belts which are better quality than the autozone/kragen brands.

Just curious as to which spacers you are referring to in back of the water pump housing?

 

I used the alt on the pulley as it’s an s5 alt but is there a difference between s4 and s5 pulleys? Also I am using my air pump as I have a 6 port and the 5th and 6th ports are actuating correctly so I don’t wanna change that. I have been using gates belts as well. The spacers seems for where the alternator bolts to the water housing.

 

I had to go through belts at Napa to find one that worked for my s4, the ones that were listed were too long and allowed no adjustments.

1. Either too much drag (alt)
or
2. The pulleys are out of alignment.

A new belt shouldn't just snap that's kinda nuts sorry mate. Check that your alternator is in good alignment and that the rail is not bent. I suspect your rail (the one the alternator adjusts on) is out of alignment or the bolts holding the alternator are bent.

Verify the pulleys are identical with calipers measure them both and eyeball the alignment / track the belt is on.

 

thanks man, the alignment appears to be good, however I’m getting belt squeak and now every light on the dash is on as well as my battery is being drained despite wiring it up the right way

 

when i have had belt problems, its been the quality of belt, Gates/Dayco/Goodyear all make pretty crappy stuff

the OE is a Bando or Mitsuboshi, its a much better product.

the other thing is that there seems to be some kind of relationship between how much torque a given belt can handle, vs how many amps the alternator puts out. if you put a stock alternator back on, your problems will probably go away. the other option is a serpentine belt setup

 

Off topic but the Bando( on Rockauto anyways) is cheaper than the Gates.

 

This may sound like a stupid question but is the alternator turning? Does it turn easily by hand? The lights on the dash sounds like the output is low, which I think it would be if it weren't turning enough rpm's. Does the high output alt. create more load than a single belt can handle as j9fd3s alludes to?

 

serpentine is not an option as I need my air pump

 

it turns very easily by hand

 

I tried a bando and it snapped after about 10 mins of driving

 

Pictures. Post plenty of pictures.

Also show video of engine running with belt, so we can see whats up. It could be a bearing catching, it could be too much load when the alternator coils engage. Visual information will help a lot here.

 

:/ i'm in the same boat...

 

I wish I could but I’m unable to as the battery is dead, the car does run fine and there’s no squeaks when the engine is cold however the car reads like 13 v. As the car runs the belt gets really hot and starts to slip and under drive the alternator. Alt bearings, water pump, and e shaft pulley bearings are all good as well as I have never had a problem with the air pump belt. Could it be that this alternator is too much load for one belt?

 

😪😪 it really sucks

 

I think you may be on to something, another option that I have recently considered is mounting a go pro in the engine bay watching the belts and pulleys while driving, might also have to put in a light. I'm going to do this to make sure my belt squeel is indeed the water pump it only does it intermittently I think it's my water pump or alternator. If someone made an auto tensioner for these belts that would be great lol.

On second thought.. I might be able to just add a bad *** spring on the tensioner bolt..

 

I have a suggestion for you. Try temporarily removing your fan clutch assembly -- there's four 10mm nuts attaching it -- from the water pump. Then check if the squeal still persists.

I've had a recent problem with an annoying squeal that would always start at 3000 rpm. Turned out that there were two items causing my 3000 rpm squeal. Those items were my fan clutch and PS idler pulley bearing. The PS pump bearing was bad too, but it wasn't contributing to my squealing problem. My fan clutch was stuck in cold operating mode and wouldn't freewheel when warm. I replaced my fan clutch, PS idler pulley and PS pump last weekend, and that solved my 3000 rpm squealing problem.

 

This is your problem. You won't drive that alternator with one belt. Especially if your battery is under charged when you start up. The HD alternator will be putting out high amperage to charge up the battery, which equals high load. The single 'v' belt just cannot handle it.