$200 for a clutched pulley?! They're about $35 for a VW, and can be changed in the car most of the time (little clearance is required) if you have the correct set of tools. There's a double splined tool set for this (the outside one engages the pulley splines, the inside the nose of the alternator) and with them and two wrenches it will come off quite easily -- unless it has seized, in which case you may have to remove the alternator and chuck the inside tool in a vise.

I believe INA or Litens makes most of these at the OE level and I bet they're the same on darn near every car that has them. If you have a CRAP (Chinese Replacement Auto Parts) alternator on the car it may have some third-party pulley on it; if so get it out of there and put a proper one on made by a decent manufacturer that will last more than a year. I've needed to replace one on my VW ALH-engined car, it was under $40, the replacement is still in service and so is the original alternator -- with 230,000 miles on the vehicle.

A lot of places will try to sell you an alternator when these fail and then they'll put some aftermarket rebuilt alternator on which is utter garbage and will fail *again*. I had a VW stealer try that on me and they wanted over $1,000 to change it; the "book" way to do is basically to pull the front clip including the radiator! However, it *does* come out the bottom on those cars if you pay attention and if the pulley is all that's bad it's a 20 minute job with it still mounted. They didn't get $1,000+ from me; I bought the tools and pulley for under $100 instead.

BTW check the tensioner and shock very carefully if this has been going on for a while. When these pulleys fail there are multiple ways they do; one of them is that they will lock up a good part of the time and that causes the tensioner to bounce a LOT, which will quickly destroy the shock on it. The other two ways they fail are "open" (don't lock either way, and is usually quite noisy, sounding sort of like rocks rolling around inside it) which results in no charging of course, and then the really ugly way -- the pulley comes apart with the engine running and you hope the pieces don't go somewhere important and cause a LOT of damage on the way out.

 

I've never known an alternator to have a clutch. Usually the load is handled electrically by the voltage regulator that increases load through the field coils in the alternator. Can someone give me an education so I can understand?

 

Sure.

Clutched alternator pulleys freewheel one direction, and lock in the other. They're most-common on diesel engines which have stronger "impulses" (when each cylinder fires) than gas motors, but are used in some gas applications as well.

Whether a particular design uses one in the serpentine path has a lot to do with exactly where in the belt path the alternator is; in the cases where it is used it dramatically smooths out the serpentine belt's operation (and is instantly visible in the quite-violent excursions of the tensioner if you accidentally install an alternator without one on it, or if the pulley on it fails in a locked-up state.)

They have nothing to do with charge management although they do tend to show up on higher-output alternator designs.

 

Welcome to the forum.
The Mk.1 alternator has a clutch, at least as far as the factory service manual is concerned on the L3 (4-cyl) ATX only. Priced at nearly $150 (dealer)/$26 (Amazon). There is no procedure for testing the mechanism in my 2004 Factory Service Manual.

The alternator needs to have the case opened to replace the bearing and on the v6 this requires removing the exhaust (groan) The bearing can be had for around $20.

EDIT: I went to the garage to verify and I indeed do not have an alternator clutch pulley (v6) but it appears they are available for the GG/GY 4cyl models. Kinda cool. thanks for the explanation @tickerguy

 

Cheers guys.
What are the original mazda series 1 alternators?

 

Mazda 6 alternators



The Mark 1 (1st gen.) was the 2003-2008. at the end of 2005 there was an update, that saw some improvements to appearance, rigidity and problem fixes (like exhaust routing for the v6)
2003-2005 is often referred to as series 1 (pre-facelift)
2006-2008 as series 2 (post-facelift)

2.3L Manual Trans. = 90 amp without clutch

2.3L Automatic Trans. 90 amp with clutch

3.0L All Trans. = 110 amp without clutch

 

Well all be! Thanks @tickerguy for the explanation. I was imagining a clutch like on a refrigerant compressor and couldn't for the life of me understand why one would be installed on an alternator.

 

Yeah, they're one of those things that people go "huh?" on when they see or hear of them for the first time. I did too. They're also something that stealers and repair shops make a mint on with unwitting owners; the pulleys fail all the time, and they're both field-replaceable and inexpensive yet the common shop answer to an alternator that is making noise and not charging is to replace the entire thing when a $40 pulley that can often be changed IN THE CAR inside of 15 minutes is all that's wrong with it. But instead of a $50-75 repair bill for a new pulley and the 15 minutes of labor to change it the unwitting will get hammered for $300-500 for a new alternator when the one in the vehicle is perfectly fine other than the pulley. It gets even worse if you go to one of the chain shops and get an alternator there; those are almost-always garbage and while they usually have a "lifetime warranty" the not-amusing part is the number of times you will be performing an R&R on it from that point forward.

And that assumes you don't go to the dealer and the "shop book" doesn't begin the change-out procedure with "remove front clip" as it does on most late 90s and early 200x model VWs (and a flat-rate book time of 4+ hours), in which case at the dealer you're going to be into them for $1,000 or more -- when what you SHOULD pay is for a $40 part and about half an hour to change it, including removing the bottom skirt so you can get wrenches on it.