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Audi Alternator Replacement
 
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Pelican Technical Article:

Audi Alternator Replacement

Peter Bodensteiner

Time:

2 hours2 hrs

Tab:

$200

Talent:

****

Tools:

all of them

Applicable Models:

 
Audi A4 (1997-01)
Audi A4 Quattro (1997-01)
Audi TT (2000-04)
Audi TT Quattro (2000-04)
VW Beetle (1999-02)
VW Golf (2000-02)
VW Jetta (2000-02)
VW Passat (1996-00)

Parts Required:

New alternator

Hot Tip:

disconnect battery before beginning

Performance Gain:

Charging system works again

Complementary Modification:

Replace belts

Changing your alternator is something you generally would only do when it fails. In the project below, I replaced it while also replacing the timing belt and the water pump. Therefore, you may notice that quite a bit more disassembly has taken place than is necessary.

One thing that may be helpful is to move the radiator into the "service position." Please see our article on this for more information. This will certainly make the job easier, as it will give you more room to work at the front of the engine. However, it may not be completely necessary. The main challenges will be a) loosening the serpentine belt enough to remove the belt from the alternator pulley, and b) removing the fan clutch and moving it out of the way enough to remove the alternator's lower mounting bolt. There are more steps to the process, of course, but these are the ones that may give you trouble without enough room to work.

The first thing that you need to do is to make sure that your alternator is indeed the cause of the problems with your charging system. Sometimes bizarre electrical problems can be caused by a number of faults other than the alternator. It's important to troubleshoot the system prior to replacing your alternator. Check the belt that drives the alternator. Is it tight and turning the alternator? If not, then check that the belt tensioner is working correctly. Modern belts seldom break, but they get brittle and glazed with age, and can slip on their pulleys. Replace the belt with a new one.

If you suspect that your alternator is failing, check the voltage at the battery. This should read a little more than 12 volts with the engine off. When the car is running, the voltage should read at in the range of 13 to 14.5 volts with the engine at 2000 rpm. If your battery appears to be leaking, then your voltage regulator has probably failed. The battery will usually only leak acid if it has been overcharged at a much higher voltage. If the voltage measured at the battery is more than 16 or 17 volts when the engine is running, then the regulator is probably bad. If your battery has boiled over and has acid overflowing out the top, make sure that you clean up any spilled acid immediately. Dousing the area with a water and baking soda solution should help considerably to neutralize the acid, and prevent it from eating away at the metal.

An important item to check on your car is the engine ground strap. The engine is electrically isolated from the chassis by rubber motor mounts. If the engine ground strap is missing or disconnected, then you might have a whole bunch of problems, including electrical system malfunctions and difficultly turning over the starter. The ground strap is located just in front of the passenger side engine mount. If you've checked all of these things and you still have charging problems, it's likely the alternator will need to be replaced.

Be sure to disconnect your battery at the negative terminal before you begin. Your radio is likely to have an anti-theft code that you'll need to have handy when you reconnect your battery--check your owner's manual. Alternatively, you can use a "memory saver" device, which will supply the radio and other components with enough power to retain their memory settings while your battery is disconnected.

I've rated this project a 4 not because it is difficult to accomplish, but because it involves a few difficult-to-reach fasteners, and because the alternator interfaces with both the engine's belts and the charging/electrical system of the car.

This view of the front of the engine should give you an idea of the general layout you'll be dealing with should you need to replace your alternator.
Figure 1

This view of the front of the engine should give you an idea of the general layout you'll be dealing with should you need to replace your alternator. Note that the radiator support panel is in the service position; normally the fan is within the fan shroud that is mounted to the back of the radiator. Take note of the lug cast into the belt tensioner as shown here (green arrow).

Before you get started unbolting the alternator from its mounts, you should disconnect the electrical connectors on the back.
Figure 2

Before you get started unbolting the alternator from its mounts, you should disconnect the electrical connectors on the back. The easiest to see and reach is on the driver's side. Insert a small flat-head screwdriver at this angle to release the plastic connector without breaking it (green arrow).

Here the connector has been detached.
Figure 3

Here the connector has been detached.

The other connection is much harder to see.
Figure 4

The other connection is much harder to see. On the 1.8T, look straight down in the gap between the number 1 and 2 intake runners. There may be a plastic cap covering the nut, which holds the connector in place on a stud that is part of the alternator. Remove the cap, loosen the nut, and the metal electrical lead will be free. If you get confused, you can use your new alternator for reference, presuming you are replacing and not rebuilding your alternator. Look at Figure 19 for another shot of this connector, taken while hooking up the new alternator.

Use a large wrench to grab the lug cast into the serpentine belt tensioner.
Figure 5

Use a large wrench to grab the lug cast into the serpentine belt tensioner. Rotate the wrench clockwise to release tension on the belt and move it off of the alternator pulley as shown here.

Two Allen-head bolts hold the alternator in place.
Figure 6

Two Allen-head bolts hold the alternator in place. The top one is 6mm, and is the shorter of the two. In this photo the serpentine belt tensioner has been removed, but even if it is in place, it will not restrict your access.

The bottom bolt has an 8mm Allen head.
Figure 7

The bottom bolt has an 8mm Allen head. The bolt is long, as it spans the width of the alternator and threads into a mounting ear on the far side of the alternator. The alternator also pivots on this bolt once you remove the top bolt. In this photo, note the distance between the head of the bolt and the fan clutch (the fan itself has been removed from the clutch in this photo). The bolt is long enough that you must remove the fan clutch and its pulley in order to pull the bolt all the way out.

Pay attention to this step, as it is not documented correctly in either the Bentley or Haynes/Chilton manual.
Figure 8

Pay attention to this step, as it is not documented correctly in either the Bentley or Haynes/Chilton manual. To remove the fan clutch, insert a screwdriver, Allen wrench, or something similar through a hole in the pulley. You can see that there are two ribs cast into the support bracket that will hold the Allen wrench in place when you remove the pulley.

Now, with the pulley braced, you can break loose the bolt that secures the pulley.
Figure 9

Now, with the pulley braced, you can break loose the bolt that secures the pulley. It's an 8mm Allen-head bolt, seen here from the back side facing the front - you can see the back of the radiator in the background.

Once the backside bolt is removed, the pulley comes off, greatly improving access to the lower alternator bolt.
Figure 10

Once the backside bolt is removed, the pulley comes off, greatly improving access to the lower alternator bolt.

Here's a good shot demonstrating how long the lower alternator bolt is.
Figure 11

Here's a good shot demonstrating how long the lower alternator bolt is.

Your alternator probably won't simply fall away once you remove the bolts.
Figure 12

Your alternator probably won't simply fall away once you remove the bolts. I used a hammer handle to pry the alternator away from its mounts.

Once the alternator is free, be ready to catch it and lift it out of the engine compartment.
Figure 13

Once the alternator is free, be ready to catch it and lift it out of the engine compartment. It's somewhat heavy, so use caution when removing it.

Old on the left, new on the right.
Figure 14

Old on the left, new on the right. As you can see, this new alternator came with a new pulley already installed. You may need to transfer your old pulley to the new alternator if it is not so equipped.

The new alternator is moved into place.
Figure 15

The new alternator is moved into place.

Thread the lower bolt through the alternator and its mounts and tighten it up to 22 ft/lbs.
Figure 16

Thread the lower bolt through the alternator and its mounts and tighten it up to 22 ft/lbs.

Rotate the alternator until the top mount is in position.
Figure 17

Rotate the alternator until the top mount is in position. Thread that bolt through and tighten it to 22 ft/lbs.

Re-attach the plastic electrical connector on the back of the alternator.
Figure 18

Re-attach the plastic electrical connector on the back of the alternator...

.
Figure 19

...and the metal one, too. Note how the flat portion of the cable fits into the slot in the plastic that surrounds the stud. Thread the nut onto the stud to hold the cable in place, and then add the plastic cap over the nut. Reattach the fan clutch, tightening the mounting bolt to 33 ft/lbs. Loosen the serpentine belt tensioner in order to create enough slack to get the belt seated on the alternator pulley. Last, reconnect your battery.

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Comments and Suggestions:
GWarner92 Comments: I have a 2000 VW Beetle 1.8T with 50,000 miles. The alternator died 3 months ago and I replaced it after removing the headlight to pass it through the opening to get it out of the engine compartment. Car was running fine with not other adjustments until this week when battery light came on and I lost power steering. Discovered that the serpentine belt was missing and replaced with a new one, only to have the same thing happen the next day. Where are my serpentine belts going? I'm ready to install another belt today but don't want this one to fall off tomorrow. What should I do to make sure it is seated properly and with right tension which all appeared fine after I put the new belt on.
June 4, 2016
  Followup from the Pelican Staff: I would inspect the tensioner and other accessory pulleys. My guess is one is faulty and running at an angle. Give The Pelican Parts parts specialists a call at 1-888-280-7799. They can figure out what part or repair kit you need.
- Nick at Pelican Parts
 
Anthony Comments: Will this work for a Gti vr6 2.8
July 19, 2015
  Followup from the Pelican Staff: No, looks like only for a 1.8.

Applicable Models:




Audi A4 (1997-01)
Audi A4 Quattro (1997-01)
Audi TT (2000-04)
Audi TT Quattro (2000-04)
VW Beetle (1999-02)
VW Golf (2000-02)
VW Jetta (2000-02)
VW Passat (1996-00) - Nick at Pelican Parts
 
samara Comments: I replaced the sensor today, cleared the code, and when I turned it off then back on the code came back. Are there two sensors in this car? I replaced one in the front of the motor.
April 2, 2015
  Followup from the Pelican Staff: Confirm the signal is getting to the DME, from the sensor.- Nick at Pelican Parts  
samara Comments: I checked the sensor and it is plugged in.
March 31, 2015
  Followup from the Pelican Staff: The sensor may have failed, coincidentally. - Nick at Pelican Parts  
Samara Comments: I had a shop replace my alternator and a couple days later the check engine light came on with a p 2089 code. When a called the shop they told me it is most likely the cam position sensor. Should I replace the sensor or make them check the timing. The car is running fine.
2005 Audi A4 1.8T
March 30, 2015
  Followup from the Pelican Staff: That code is for the camshaft sensor circuit. Check that the sensor is plugged in. It may have been left disconnected during the repair. - Nick at Pelican Parts  
Cheryl Comments: Thanks so much! If the ground strap is connected, is there an easy way to test the ground strap and connection to detect if it is faulty?
July 7, 2014
  Followup from the Pelican Staff: Yes. Test it using the voltage drop method. - Nick at Pelican Parts  
Burt6600 Comments: In previous comment, I ground the end to 5mm radius should have been 5mm diameter!
June 9, 2014
  Followup from the Pelican Staff: Thanks for the additional info. We appreciate it.
- Nick at Pelican Parts
 
Burt6600 Comments: I just finished removing the Alternator on a 2001 A4 Avant Quattro Here are some comments.
I did have to remove the fan hub but nothing else. The Allen key did not work nor did the 5x60mm bolt called out in the manuals. They bent like putty and 60mm is not long enough. I pretty much had to fill the gap in the slots on the housing with an 8mm diameter rod 90 mm long. I ground the end to 5mm radius. The fan didn't need to come out I just dropped it down below when I got the bolt out. That was good enough.
The electrical connector was a challenge. But a small bladed screw driver needs to be inserted from the drivers side to lift up the small plastic locking bar. Use a mirror, it was invaluable. I used a 12 inch adjustable wrench to release belt tension to remove the belt and then put a screw driver through the hole in its end while it was still under tension and that stopped it falling down the gap between radiator and engine. Then it was ready when I needed to replace the belt on the pulley.
It wasn't particularly easy to do, not much on this car is, but it was doable.
June 8, 2014
  Followup from the Pelican Staff: Thanks for the additional info and feedback. We appreciate it.
- Nick at Pelican Parts
 
a4_hypee Comments: great write up! very very helpful! If my plastic connector is not there and is an o ring identical to the metal connector, do I need to change/update the whole wire harness or can I do something to splice in a connector?
April 4, 2014
  Followup from the Pelican Staff: Thanks for the feedback.

You'll have to update it. I would not splice it in. - Nick at Pelican Parts
 

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