Alternator removal for jetta passat mk3
Difficulty: 2/5
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Introduction

The alternator charges the battery which provides the electrical needs of your car.  The alternator is a wear item and needs to be replaced on an as needed basis.  Symptoms of a bad alternator would be the battery warning light coming on, less than 14V at the battery when the engine is running, or dimming headlights when the electrical load is higher than normal (and you know the battery is good).  

The part that sees the greatest wear are the brushes and copper contacts.  These are the parts that connect the rotating part of the alternator's electricity to the non rotating part of the alternator.  In these 120amp alts, the brushes are held by the voltage regulator.  Since the voltage regulator and brush costs about $95 and a rebuilt alternator costs $110, getting an alternator may be faster.  Note that the spec on the voltage regulator states that at minimum wear they should have at least 5mm movement.  If the diodes start to go bad that convert the AC to DC you can also lose amperage output and still be at 14V.  The bearings and pulleys also see wear but they should have very long lives if properly tensioned. 

If you are having a charging problem, it's either the alternator or instrument panel light, battery, or grounds.  The battery voltage when the car is off should be over 12V.  The battery voltage when the engine is running should be at least 14V even at idle.  If it's the alternator, the problem could also be in the instrument panel.  There is a low voltage warning light in the instrument panel of the mk3 cars.  If it burns out, the alternator will not charge the battery properly.  It could also be a loose battery terminal or ground that prevents proper charging of the battery.  If you are not sure, take the alternator to an auto parts store because many places will check it for free.

Parts

metric sockets
adjustable wrench
6mm allen wrench

Procedure

Remove the negative (-) battery terminal.

Release the tension on the alternator by using a wrench to move the tensioner arm.  The service manual says that you can use the pulley bolt to move hte lever arm, but I found this to be stressful on the bolt and may tighten it.  Remove the alternator belt. 

Remove the 2x 6mm allen bolts (circled in red below) that hold the tensioner spring so that you can get access to the lower alternator bolt.  Removing the belt first so that the spring is not under tension will make removing those bolts easier.  

Remove 2 bolts that hold the alternator in place, marked with red circles below on the left side.  You can use a socket that is larger than the metal bushing pressed into the alternator, to tap the alternator away from the bracket, marked by the red arrow.  This will loosen the tension on the bushings so that the alternator should be loose.  You can try to pry it out without releasing this tension but it'll be harder. 

Remove 2 more bolts that hold the alternator cable in place.  The alternator should now be easily removed.  Clean all grounds as necessary. 

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