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N54 Engine Drive Belt, Tensioner, Idler Replacement
 
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Pelican Technical Article:

N54 Engine Drive Belt, Tensioner, Idler Replacement

Nick Czerula

Time:

2 hours2 hrs

Tab:

$150

Talent:

****

Tools:

Set of sockets, wrenches, screwdrivers

Applicable Models:

BMW 535i/xi Sedan (2008-10)
BMW 535xi Wagon (2008)

Parts Required:

Drive belt, tensioner, idler pulley

Hot Tip:

Mark direction of belt rotation before removing

Performance Gain:

Proper engine accessory operation

Complementary Modification:

Inspect and replace pulleys

Engine accessories on BMW E60 N54 (turbocharged) engines consist of the power steering pump, the alternator and the AC compressor. A single multi-ribbed engine drive belt (often called the serpentine belt) is driven by the crankshaft pulley (vibration damper) and drives the accessories pulleys at the front of the engine. The belt is routed and tensioned using three idler pulleys and one tensioner pulley.

Note that the engine cooling fan and engine coolant pump are both electric and not belt-driven.

The serpentine belt is tensioned by a strong spring and does not need periodic adjustment. But it will, over time and due to heat, cold and the rigors of operating multiple pulleys, develop signs of wear, which include: cracks, fraying, glazing or missing chunks. In addition, the tensioner and idler pulleys may develop defects. Bearings in these pulleys are lifetime lubricated. The lubrication eventually dries up or wears out and may cause noises. If a pulley bearing deteriorates, it can tilt and allow the belt to fly off the pulleys. If it seizes it can damage the belt quite quickly due to excessive friction.

With your engine cold and turned OFF, inspect your drive belt for wear. Replace your belt if any of the previously mentioned issues (cracks, fraying, glazing or missing chunks) are present or every four years. In this article, I'll go over the steps involved with replacing the drive belt on the N54 engine. Be sure to work with a cool engine and remove the key from the ignition.

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 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 leave your vehicle information.

BMW E60 models utilize one multi-rib engine drive belt (blue arrow).
Figure 1

BMW E60 models utilize one multi-rib engine drive belt (blue arrow). The belt may be referred to as a serpentine belt because it snakes around the engine accessories. The front charge air duct has to be removed to access it. Start by removing the electric cooling fan. See our tech article on N54 engine oil cooler / cooling fan replacing. Then remove the front charge air duct. See our tech article on charge air duct replacing. Before removing the drive belts, mark the direction of rotation (if reusing belts) and note the installation position.

Note the belt routing and position before removing.
Figure 2

Note the belt routing and position before removing. Use this photo to help with reinstalling. The red arrow points to the crankshaft pulley. The blue arrow points to the alternator.

Next, using a T60 Torx socket on a long handled ratchet, rotate the belt tensioner clockwise to release the belt tension.
Figure 3

Next, using a T60 Torx socket on a long handled ratchet, rotate the belt tensioner clockwise to release the belt tension. With the tension released, pull the belt off the tensioner pulley. Then remove the belt from the remaining pulleys and remove it from the engine. With the belt removed, inspect the pulleys for lateral play or binding. The idler pulleys (red arrows) commonly fails and causes the drive belt to come off. Now is a good time to replace the idler pulleys to prevent future problems. To replace the tensioner and pulleys see the following steps. To install the accessory drive belt, begin by wrapping the belt around the crankshaft pulley. Then route the belt over and around the AC compressor pulley, around the power steering pulley, around the idler pulley and around the alternator. Once the belt is properly installed on all accessories, release the tensioner as described earlier and slide the belt onto the tensioner pulley. Check that it is properly aligned and installed in all the pulley grooves correctly. Be careful not to force the belt onto the pulleys. Damage may occur. Release the tensioner and recheck that the belt is properly aligned.

This photo shows the tensioner (blue arrow) and idler pulleys (red arrows) with the drive belt removed.
Figure 4

This photo shows the tensioner (blue arrow) and idler pulleys (red arrows) with the drive belt removed. To replace the tensioner or an idler pulley, lever the plastic cover at the front of the pulley off using a flathead screwdriver.

Tensioner: Loosen the T45 Torx fastener (red arrow) and remove the tensioner with the lower idler pulley.
Figure 5

Tensioner: Loosen the T45 Torx fastener (red arrow) and remove the tensioner with the lower idler pulley. Reverse the steps to install the new tensioner.

Idler: To replace an idler pulley, lever the plastic cover (green arrow) at the front of the pulley off using a flathead screwdriver.
Figure 6

Idler: To replace an idler pulley, lever the plastic cover (green arrow) at the front of the pulley off using a flathead screwdriver. Remove the T45 Torx fastener (red arrow) and remove the idler pulley. Reverse the steps to install a new idler. The blue arrow points to the idler attached to the tensioner, which is replaceable separately. The third idler pulley is blocked by the ratchet handle. It was indicated in the previous image.

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Comments and Suggestions:
paraglider Comments: can this be done with the radiator fan still in place? And also does do you have directions for upper coolant hose replacement.? Thanx in advance.
August 24, 2017
  Followup from the Pelican Staff: Hoses shown here: http://www.pelicanparts.com/techarticles/BMW-E60/19-WATER-Radiator_Replacing/19-WATER-Radiator_Replacing.htm

it can, but be careful not to damage radiator. - Nick at Pelican Parts
 
Peralta BMW Comments: Hi hoping you can help me narrow down if I need to replace my compressor or not. I have 2005 525i, when I turn on the AC the belt tensioner starts bouncing. There is a noise coming from that area but I cannot determine if it is the compressor or something else. I replaced the belt tensioner but still the same bouncing and noise. Thoughts?
August 15, 2017
  Followup from the Pelican Staff: I would remove the drive belt. Then check each pulley for binding or looseness. You will have to manually check with the engine off. - Nick at Pelican Parts  
Al Comments: Do you know the size of the bolt that fits in the idler pulley connected to the alternator?
May 23, 2017
  Followup from the Pelican Staff: No I do not. 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
 
BmwNoob Comments: I have bmw 528xi 2008 and I want to change the belt and Tensioner and also idler pulley.. will these steps be the same for my year and model?
January 1, 2017
  Followup from the Pelican Staff: No, this is the N54 engine. It is similar but not the same. This engine is closer, but not exactly like yours http://www.pelicanparts.com/BMW/techarticles/BMW-3-Series-E90/BASICS-Drive_Belt_Replacement/BASICS-Drive_Belt_Replacement.htm - Nick at Pelican Parts  
Roger Smith Comments: My car been making a ratting/whining noise when I drive, I changed the serpentine belt but the noise is still there, any clues what it might be? Thank you.

Bmw 2009 e60 535i xdrive
November 12, 2016
  Followup from the Pelican Staff: The tensioner or an accessory component could be faulty. - Nick at Pelican Parts  
winmutt Comments: Torque numbers on pulleys and tensioner?
August 28, 2016
  Followup from the Pelican Staff: I don’t have that info.

I would grab a repair manual. It will have the procedure, special tools and torque specs.

Give our parts specialists a call at 1-888-280-7799. - Nick at Pelican Parts
 
James Comments: Nick how do I remove the cooling fan from my 2008 535i I'm getting ready to change my belt and tensioner and pulleys thanks
August 22, 2016
  Followup from the Pelican Staff: Your vehicle is similar to this article:

http://www.pelicanparts.com/techarticles/BMW-E60/12-WATER-Engine_Cooling_Fan_Replacement/12-WATER-Engine_Cooling_Fan_Replacement.htm

YOu will have a few extra ducts due to the turbocharger. - Nick at Pelican Parts
 
tony Comments: looking for the wright drive belt routing for a 2008 535i
any one?
July 27, 2016
  Followup from the Pelican Staff: fig 2 shows the routing. - Nick at Pelican Parts  
Mike C Comments: Nick I'm working on a 2008 535xi wagon for one of my business partners, it broke its serpentine belt. The car was immediately parked when this occurred and towed to thier dealer, who gave them an est of just about 8 THOUSAND to replace. They are saying the alternator has to be replaced as well I see or feel nothing that warrants this, the alt still spins smoothly and has no visible damage and also are telling us that pieces of the belt can get through the front crank seal and want to disassemble the pan to check the pickup screen. To me, this sounds about as far-fetched as anything I've ever heard about an engine. Like I said, as soon as the broken belt was heard the car was shut off and has not been started since. Replacing the belt seems pretty straightforward to me, can that be done then monitor the crank seal for a leak? There is no evidence of leakage now but the engine can't be started to put the seal under pressure w/o first replacing the belt. What are your thoughts? Thank you sir...
May 27, 2016
  Followup from the Pelican Staff: The belt entering the crank seal is common, so if the seal is physically damaged from the belt failing, it may be warranted. Their fear is if debris gets into the oil pump, the engine is a goner.

My suggestion, find out why the belt failed. Remove the crankshaft pulley and inspect the seal. If Ok, replace the failed component and the belt. Then start the engine, confirm there are no leaks. - Nick at Pelican Parts
 
Jr Comments: I have a 2008 528i the belts was shredded into pieces. I wonder Wat cause it to do that?? And how long would it take to put the belt back on??
May 25, 2016
  Followup from the Pelican Staff: This article shows you how to install the belt.

There is likely a faulty component. Tensioner, pulley, alternator, etc. - Nick at Pelican Parts
 
Francy Comments: I have a 2009 528i, and it's been making squealing noise that comes and goes on a weekly basis. When I step on the accelarator, it stops, and comes back on when I let go. Also, it shut off, all of a sudden, while driving. Any ideas on what I need to replace.?
March 31, 2016
  Followup from the Pelican Staff: rd to say, you'll have to to do some testing. When your engine stalls, hesitates or doesn’t start you’ll want to check the basics. Check spark, fuel injector pulse and fuel pressure, volume, quality and engine compression. Are there any fault codes? Once you figure out what is missing, it will be easier to diagnose.
- Nick at Pelican Parts
 
Stevarino Comments: I have a 2008 335i with only 20,000 miles. It spends weeks sitting in the garage while I am away. Should I have the original belt replaced due to eight years of exposure? Car always garaged and driven in good weather.
February 15, 2016
  Followup from the Pelican Staff: It's not a nad idea. If the belt looks good and isn't dry rotted you may be able to leave it a while longer. - Nick at Pelican Parts  
Lee Comments: Hey Nick, I have an 08 335i with 135k miles on it. It's been around 20 degrees outside lately when I start my car in the garage. It has a slight squeak when running from the belt area. However, if I drive for awhile and pop the hood once I return, the squeak goes away. I checked the belt and all looks good, no wear, no oil and the tension on the belt seems fine. Any clue why the sounds goes away once warm? What should I look at next?
January 18, 2016
  Followup from the Pelican Staff: Likely the belt tensioner is starting to wear out. - Nick at Pelican Parts  
phil Comments: in figure 1, looks like you had to remove the tubes going into the front oil filter housing. If so, do I have to drain the oil?

Also looks like you removed the front bumper. Is this necessary?
November 17, 2015
  Followup from the Pelican Staff: We removed the cooling fan. Not lines. If your vehicle has cooler lines from the oil filter housing, you may have to remove them. - Nick at Pelican Parts  
Bmrboy Comments: I have a 2008 BMW 528i Sort with 94.7K miles. Lately, I have been hearing a slight squeaking noise emanating from the front end/engine compartment after the car had been driven for an hour or so and is warm. I do not hear the noise when the car is cold nor when driving around short distances. Could this be a sign that the serpentine belt needs replacing?
June 29, 2015
  Followup from the Pelican Staff: Could be. Try spraying a small amount of water on the belt. If the noise goes away, replace it. - Nick at Pelican Parts  
George Comments: The drive belt on our 2010 535xi broke today while me wife was driving. Happen just as she was approaching the house. I was going to disassemble and repair myself, but started reading horror stories about pieces of belt getting into the engine through the front crank seal. I started thinking I better get it to a dealer or shop to have them check because of the catastrophic engine damage I've read about. Wondering if this is a concern with our model and year? appreciat any insight you can provide on this matter.
FYI. Your comment submission guidelines do not come up when selecting the link.
June 28, 2015
  Followup from the Pelican Staff: Check if there is debris from the belt behind the crankshaft pulley or signs of oil leaking. If not, you may have caught it soon enough. - Nick at Pelican Parts  
jesper Comments: nevermind my comment..this is for E60 :
April 29, 2015
  Followup from the Pelican Staff: OK, thanks for letting us know. - Nick at Pelican Parts  
jesper Comments: if this is the N54 twinturbo engine, where is the intake for the front turbo?..it runs across the front right where the pulleys are?..
April 29, 2015
  Followup from the Pelican Staff: Step 1, the red arrow points to the duct I think you asking about. - Nick at Pelican Parts  
Peter Comments: What are the torque specs for the tensioner bolt and the idler pulley bolt?
Thanks for you many repair articles. They are great!

March 16, 2015
  Followup from the Pelican Staff: The only one I can find for the N54 engine, is the idler pulley at the alternator. 80 Nm. - Nick at Pelican Parts  

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Page last updated: Tue 10/17/2017 02:49:22 AM