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S54 6-Cylinder Engine Drive Belt Tensioners Replacement
 
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Pelican Technical Article:

S54 6-Cylinder Engine Drive Belt Tensioners Replacement

Nick Czerula

Time:

3 hours3 hrs

Tab:

$150

Talent:

****

Tools:

Set of sockets, wrenches, screwdrivers

Applicable Models:

BMW Z4 Convertible (2003-06)
BMW Z4 Coupe (2006)

Parts Required:

Drive belt tensioners, bearings, hydraulic tensioner

Hot Tip:

Work with a cool engine

Performance Gain:

Proper engine accessory operation

Complementary Modification:

Replace drive belts

Two drive belts in the S54 6-cylinder engine drive the accessories pulleys at the front of the engine. A serpentine belt drives the power steering pump, coolant pump and alternator, and the AC compressor is driven by a separate belt. A tensioner pulley tensions each belt.

Note that the engine cooling fan is electric and not belt-driven.

The belts are tensioned by strong tensioners and do not need periodic adjustment. But they will, over time and due to heat, cold and the rigors of operating multiple pulleys, develop signs of wear: cracks, fraying, glazing or missing chunks. In addition, the tensioners and idler pulleys may develop defects. Bearings in these pulleys are life-time lubricated. The lubrication eventually dries up or wears out and may cause noises. If it seizes it can damage the belt quite quickly due to excessive friction. This kind of failure can occur when you least expect it. There are a few warning signs; listen for increasing belt noise, chirping or grinding from the belt area. If you have any of these symptoms, remove your drive belts and inspect the idler and tensioners. Also inspect the main drive belt tensioner for straightness. As the tensioner bearing wears it can tilt, causing your drive belt to fail. If you have a chirping sound from your hydraulic tensioner, it could be bad needle bearings. This can be remedied by rebuilding or replacing the main drive belt tensioner. I will show you both methods in this tech article.

Keep in mind that when your car was serviced before, parts may have been replaced with different size fasteners used in the replacement. The sizes of the nuts and bolts we give may be different from what you have, so be prepared with different size sockets and wrenches.

Protect your eyes, hands and body from fluids, dust and debris while working on your vehicle. If you're working with the electrical system, disconnect the battery before beginning. Always catch fluids in appropriate containers and properly dispose of any fluid waste. Recycle parts, packaging and fluids when possible. Never work on your vehicle if you feel the task is beyond your ability.

Our vehicle may vary slightly from yours as models do change and evolve, as they grow older. If something seems different, let us know and share your info to help other users. Do you have questions or want to add to the article? Leave a comment below. When leaving a comment, please include your vehicle information.

Be sure to work with a cool engine and remove the key from the ignition. Remove the lower engine splash shield. Remove both drive belts. See our tech article on drive belts replacing.

BMW Z4 models equipped with an S54 6-cylinder engine utilize two multi-ribbed engine drive belts.
Figure 1

BMW Z4 models equipped with an S54 6-cylinder engine utilize two multi-ribbed engine drive belts. A small outer belt drives the A/C compressor and the larger inner belt drives the alternator, coolant pump, and power steering pump.

This photo shows the A/C belt tensioner is pointed out with the green arrow.
Figure 2

This photo shows the A/C belt tensioner is pointed out with the green arrow. The accessory (main) drive belt tensioner is shown with the red arrow. The idler pulley for the main drive belt is pointed to by the green arrow.

A/C belt tensioner: The punch (yellow arrow) should still be in place from removing the belt.
Figure 3

A/C belt tensioner: The punch (yellow arrow) should still be in place from removing the belt. This also allows access to the upper fastener (red arrow). Once the upper fastener is removed, remove the punch. Then remove the lower 13mm fastener (green arrow).

A/C belt tensioner: Using a 13mm socket, remove the upper tensioner mounting fastener.
Figure 4

A/C belt tensioner: Using a 13mm socket, remove the upper tensioner mounting fastener. Then, use a 16mm wrench. Relieve the tension on the tensioner and remove the punch. Then remove the lower fastener.

A/C belt tensioner: Remove the tensioner from the engine (red arrow).
Figure 5

A/C belt tensioner: Remove the tensioner from the engine (red arrow). When installing a new tensioner, hand tighten the lower fastener. Then move the tensioner into the relieved position and hold it in place with a punch. Install and tighten the upper fastener. Then tighten the lower fastener. Start the engine and allow it to run for less than 30 seconds. Shut the engine OFF and recheck the belt installation.

Accessory belt idler pulley: Remove the idler pulley dust cap (red arrow).
Figure 6

Accessory belt idler pulley: Remove the idler pulley dust cap (red arrow). Use a small flathead screwdriver to lever it off.

Accessory belt idler pulley: Remove the 16mm idler pulley fastener (red arrow).
Figure 7

Accessory belt idler pulley: Remove the 16mm idler pulley fastener (red arrow).

Accessory belt idler pulley: Unscrew and remove the idler pulley from the engine with the long bolt (red arrow).
Figure 8

Accessory belt idler pulley: Unscrew and remove the idler pulley from the engine with the long bolt (red arrow). Install the new idler pulley. Be sure to align the tab on the pulley (green arrow) and slot on the engine (yellow arrow) and tighten the fastener. Reinstall the drive belts. Start the engine and allow it to run for less than 30 seconds. Shut the engine OFF and recheck the belt installation.

Accessory belt tensioner: Working at the top of the tensioner, remove the dust cap (red arrow).
Figure 9

Accessory belt tensioner: Working at the top of the tensioner, remove the dust cap (red arrow). Then loosen the 13mm fastener (green arrow).

Accessory belt tensioner: Remove the tensioner pulley dust cap (red arrow).
Figure 10

Accessory belt tensioner: Remove the tensioner pulley dust cap (red arrow). Use a small flathead screwdriver to lever it off. Using an 8mm Allen bit, loosen the tensioner pulley mounting bolt.

Accessory belt tensioner: Remove the pulley with the bolt.
Figure 11

Accessory belt tensioner: Remove the pulley with the bolt. Be sure not to misplace the pulley shim (red arrow).

Accessory belt tensioner: Working below the pulley mounting bore (green arrow), remove the 13mm tensioner mounting fastener (red arrow).
Figure 12

Accessory belt tensioner: Working below the pulley mounting bore (green arrow), remove the 13mm tensioner mounting fastener (red arrow).

Accessory belt tensioner: This photo shows both tensioner fasteners (green arrows) with the alternator removed for clarity.
Figure 13

Accessory belt tensioner: This photo shows both tensioner fasteners (green arrows) with the alternator removed for clarity. Be sure they are both removed. Using a pry bar, gently lever the tensioner away from the engine and remove it.

Accessory belt tensioner: Remove the tensioner (green arrow) from the engine by sliding it off the (red arrow) pivot pin (yellow arrow).
Figure 14

Accessory belt tensioner: Remove the tensioner (green arrow) from the engine by sliding it off the (red arrow) pivot pin (yellow arrow). At this point, you can either replace the entire tensioner assembly, or rebuild yours. If you replace it, just install the tensioner in the reverse steps of its removal. To rebuild the tensioner, see the next few steps. Be sure to use silicone grease on the pivot pin when reassembling.

Accessory belt tensioner: Secure the tensioner in the vise.
Figure 15

Accessory belt tensioner: Secure the tensioner in the vise. Remove the 13mm hydraulic strut fasteners. Then remove the strut from the tensioner.

Accessory belt tensioner: With the strut removed, you can now replace the needle bearings inside the tensioner.
Figure 16

Accessory belt tensioner: With the strut removed, you can now replace the needle bearings inside the tensioner. These are the items that cause the chirp or squeak. Before removing the old bearings, measure and note the installation depth of each. The front bearing (red arrow) is installed deeper than the rear bearing (green arrow).

Accessory belt tensioner: Using a brass punch, drive the needle bearings out of the tensioner.
Figure 17

Accessory belt tensioner: Using a brass punch, drive the needle bearings out of the tensioner. Tap the perimeter of the bearing as you drive it out. Doing so will ensure that it comes out straight.

Accessory belt tensioner: Using a soft-faced hammer, drive the new bearings into the tensioner at the previously noted depth.
Figure 18

Accessory belt tensioner: Using a soft-faced hammer, drive the new bearings into the tensioner at the previously noted depth. Install the new hydraulic strut to the tensioner. Then install the tensioner to the engine.

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Page last updated: Fri 12/9/2016 02:54:55 AM