Audi Parts Catalog Audi Accessories Catalog Audi Technical Articles VW-Audi Tech Forums
 
  Search our site:    
View Recent Cars  |   Cart  | Project List | Order Status | Help    
 >  >
Audi A4 Idler Pulley Replacement
 
Bookmark and Share

Pelican Technical Article:

Audi A4 Idler Pulley Replacement

Steve Vernon

Time:

1 hour1 hr

Tab:

$30

Talent:

**

Tools:

17mm, T55 Torx

Applicable Models:

Audi A4 (2002-05)
Audi A4 Cabriolet (2003-06)

Parts Required:

New idler pulley

Hot Tip:

Don't work on a hot engine

Performance Gain:

Won't leave you stranded at the side of the road

Complementary Modification:

New belt

There are two belts on the Audi A4 1.8 liter engine, the timing belt and the accessory or drive belt. Both belts have tensioners and idler pulleys that are used to keep the belts under a constant tension and running straight over the accessory pulleys. This article will deal with the drive or accessory belt repair and maintenance.

The drive belt is mounted on the front of the engine and is turned by a pulley on the end of the crankshaft. This belt is responsible for running the power steering pump, A/C and alternator.

While the tensioner is used to keep a constant tension on the belt, the idler pulley is used to assist in keeping the belt running straight as well putting a tension point between two of the accessories. A worn or failing idler pulley can lead to improper function from the accessories it drives, fraying of the belt, and excessive noise from the engine and eventually to destruction of the belt itself, which will leave you stranded.

You should check the condition of the belt tensioner and pulley ever six months and replace it as need and certainly before failure. The only nice thing about a failing idler pulley is that they usually make a very loud squealing sound as they start to go bad. If you notice a squeal coming from the engine compartment check the idler pulley first thing.

If the pulley is lose or wiggles side to side in any manner it needs to be replaced right away.

Unfortunately, replacing the idler pulley involves removing the front bumper and placing the lock carrier in the service position. Please see our articles on these procedures for additional assistance. Changing the pulley is a relatively simple job, whereas moving the lock carrier is much more time consuming. If you are going to go to all this work you may want to consider replacing the belt and tensioner while you are at it.

Let the car cool so you don't have to work around a hot engine.

You will need to remove the belt from the tensioner, idler pulley and accessory pulleys to replace the idler pulley.
Figure 1

You will need to remove the belt from the tensioner, idler pulley and accessory pulleys to replace the idler pulley. Looking down from the top of the engine, you can see the tensioner (red arrow) just to the left of the alternator (yellow arrow, when facing the motor).

You will need to take the tension off of the tensioner to remove the belt.
Figure 2

You will need to take the tension off of the tensioner to remove the belt. The tensioner has a "nub" on the top outer portion. You can place a 17mm wrench (red arrow) on this and turn it clockwise. You can now slip the belt off or lock the tensioner in the open position.

To lock the tensioner in the open position turn the tensioner all the way clockwise and insert a retaining pin between the rotating part and the tensioner base through the locking slot (red arrows).
Figure 3

To lock the tensioner in the open position turn the tensioner all the way clockwise and insert a retaining pin between the rotating part and the tensioner base through the locking slot (red arrows). If you do not have a retaining pin you can use a 5mm Allen key.

With the tensioner locked you can slip the old belt off.
Figure 4

With the tensioner locked you can slip the old belt off. You can see that this belt is past its good use date and has started to crack around the edges (red arrow).

Use a T55 Torx and reach down between the shroud and pulley.
Figure 5

Use a T55 Torx and reach down between the shroud and pulley. Even with the lock carrier in the service position it will be a tight fit. Insert the Torx and remove the old bolt (red arrow) and pulley.

This is a photo of the old pulley out of the vehicle.
Figure 6

This is a photo of the old pulley out of the vehicle. You can see that the pulley rotates around the bolt on a bearing. When the bearing starts to go bad the pulley can develop a wobble. This will lead to the squealing sound and eventual failure of the pulley.

Install the new idler pulley.
Figure 7

Install the new idler pulley. Audi considers the bolt to be single use only and should be replaced. Some pulleys come with a new bolt. Be sure to check when ordering. The new belt will be a tighter fit so you may have to use the 17mm wrench and pull back on the tension as far as possible to get the new belt on. This diagram shows you the proper routing of the belt with the idler pulley indicated by a red arrow. Installation is the reverse of removal. Do not forget to check that the belt is sitting fully in the groves of each pulley.






Bookmark and Share

  Search our site:    

View Cart & CheckOut | Project List | Order Status |  Help    

 

[Home] [Customer Service] [Shopping Cart] [Project/Wish List]
  [Privacy Statement]  [Contact Us] [About Us] [Shipping] [Careers]

Copyright © Pelican Parts Inc. -    DMCA Registered Agent Contact Page

Page last updated: Wed 12/7/2016 02:46:06 AM