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- Repair Summary
- Repair Difficulty and Cost
- Repair Video
- Parts Diagram
- Required Parts List
- Repair Steps
Repair Summary
The following article gives detailed instructions on replacing the belt tensioner pulleys on a BMW E60 5 series car with the M54 six-cylinder engine. Even though we have used a 2005 BMW 530i to perform this installation, this article can be applied to any BMW vehicle with the M54 six-cylinder engine with minor modifications to the repair steps below.
See all vehicles this article applies to
E60 5 Series M5
E60 5 Series 523Li
E60 5 Series 550i
E60 5 Series 545i
E60 5 Series 540i
E60 5 Series 535d
E60 5 Series 530xi
E60 5 Series 530xd
E60 5 Series 530Li
E60 5 Series 530i
E60 5 Series 530d
E60 5 Series 525i
E60 5 Series 525xi
E60 5 Series 525Li
E60 5 Series 525d
E60 5 Series 523i
E60 5 Series 520i
E60 5 Series 520d
A BMW E60 tensioner pulley replacement will help cure one of the most annoying sounds you will encounter in your 2004-2010 5 series...the dreaded squealing sound from under the hood.
***Please note this repair is for the BMW E60 with the M54 6 cylinder engine (525i and 530i) with the mechanical accessory belt tensioner. Other E60 models and engines may differ.
Unlike many of the BMW repairs we cover, belt, and pulley squeal is simple to identify without the need of any fancy diagnostic equipment. You can hear it from 50 feet away; that embarrassing nerve grating squeal from under your hood that sounds like fingernails scraping on a chalkboard. The sound is a clear indication that your vehicle may require a belt and pulley repair.
The main accessory belt is powered by the crankshaft pulley and drives the vehicle's water pump, power steering pump, and alternator. The tensioner and idler pulleys help guide the accessory belt, applying the correct amount of pressure so it doesn't slip or break. As the tensioner and idler pulleys begin to age, their internal bearings start to fail to emit an annoying squeak. The pulleys should be replaced as soon as possible at the first signs of wear. A failed pulley can seize up precipitating the accessory belt to break and possibly causing catastrophic engine damage.
The AC tensioner pulley is located at the bottom of the engine and is responsible for keeping the air conditioning drive belt spinning the ac compressor. Just like the accessory belt tensioner, it is susceptible to internal bearing failure and should always be replaced as well.
When performing a BMW E60 belt tensioner replacement, it is also good practice to replace the two drive belts. The main accessory belt, or serpentine belt, on your BMW E60 serves the critical function of operating your alternator, water pump, and power steering pump. The second accessory belt, or a/c belt, operates the air conditioning compressor. As these belts age, they become worn. The heat and stress put on them from the engine cause "dry rot", a condition where the belt will actually start to crack. A broken main accessory belt can quickly cause catastrophic engine failure due to overheating.
Take the time to familiarize yourself with the following BMW M54 engine diagram showing the location of the belts and pulleys that need to be replaced.
Please note that this repair article deals with the BMW M54 engine with a mechanical accessory belt tensioner. Many M54 six cylinder engines were produced with the "old style" mechanical belt tensioner for the main accessory belt.
The mechanical belt tensioner was later replaced with the updated, more reliable hydraulic belt tensioner.
If you want to upgrade your mechanical belt tensioner with the newer hydraulic version during this repair, there is a very simple kit you can purchase to do this. We have provided a link to the kit in the parts section below for your convenience.
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Includes detailed part diagrams, part numbers and links to purchase all of the required components needed to complete this repair.
Before starting this repair, you must have the following required parts.
All BMW models with M54 six cylinder engine
Keeping all of your belts tight is imperative to keeping everything in your vehicle functional. If your A/C belt tensioner pulley is not keeping enough tension on your belt, your entire A/C system won't work as effectively. A usual sign that your tensioner needs replacing is if your belt keeps slipping causing the system to "squeal".
All BMW vehicles with the M54 six cylinder engine
If the belt in your vehicle recently fell off it might be because the tensioner in your vehicle is broken. To prevent from this happening again replace your tensioner today with this direct replacement.
All BMW E60 with M54 engine.
This pulley controls the water pump and alternator belt. Commonly the cause of bearing noise underhood.
All BMW E60 models with M54 six cylinder (525i and 530i)
Accessory belts keep everything turning off of the crank pulley. AC compressors rely on this belt to keep everything working properly. If your drive belt is getting old, cracking, glazing, or squeaking, replace it. It's easy to see when the belts are beginning to wear. Visually, the belt will begin to glaze on the underside, making it far less effective. Cracks can appear on the back of the belt from “dry rot” caused by exposure to engine heat or age. Squealing is common on worn belts which basically means that the belt is slipping on pulleys. In either case, your vehicle needs a new belt.
BMW E46 and E60
Accessory belts keep everything turning off of the crank pulley. Generator, fans, water pumps and AC compressors all rely on this belt to keep everything working properly. If your drive belt is getting old, cracking, glazing, or squeaking, replace it. It's easy to see when the belts are beginning to wear. Visually, the belt will begin to glaze on the underside, making it far less effective. Cracks can appear on the back of the belt from “dry rot” caused by exposure to engine heat or age. Squealing is common on worn belts which basically means that the belt is slipping on pulleys. In either case, your vehicle needs a new belt.
All BMW vehicles with the M52 or M54 six cylinder engine
If you are interested in replacing your mechanical belt tensioner with the more reliable hydraulic system, then this is the kit for you. Kit includes hydraulic tensioner, pulley, and all necessary hardware for the easy bolt on conversion.
Fits all BMW models with M54 engine
Complete hydraulic tensioner assembly for your BMW alternator/water pump belt does not come with pulley/roller. This complete assembly comes with relay lever assembly & the hydraulic tensioner.
Section 1 - Removing the BMW E60 Tensioner Pulleys
- Jack and support the front end of your vehicle. You will need to get under the front of the car to access the AC belt and tensioner pulley. Not sure how to jack and support your BMW? Read our article on the simple and safest way by clicking here.
- The first belt to be removed from your vehicle is the AC accessory belt. You will need to remove the pressure being put on the AC belt by the belt tensioner pulley so the belt can be removed. There is a recessed torx (star) fitting on the front of the belt tensioner (see image below). Take a 3/8" hex wrench, insert it into the torx fitting, and use your muscles to turn CLOCKWISE. The pulley will retract downward allowing you to remove the belt. ***The reason we use a 3/8" hex wrench instead of a torx bit is due to clearance issues in the engine compartment. Unless you have a special low profile ratchet or modified torx bit, you will not be able to get to the torx fitting using that combination. The 3/8" hex wrench is easy and works perfectly!
- Using a 16mm socket wrench, remove the ac tensioner pulley mounting bolt. Remove the tensioner pulley from the car.
- Working from the top of the engine, find the main accessory (serpentine) belt tensioner pulley. This tensioner pulley is slightly different from the ac tensioner pulley - in order to release the belt pressure you will need to use a 16mm socket wrench instead of a hex wrench. There is a 16mm raised fitting on the front of the belt tensioner - use a 16mm socket wrench and turn clockwise to release the pressure on the main accessory belt. Grasp belt and remove from vehicle.
- The main accessory tensioner pulley is mounted to the front of the engine with two 13mm bolts, located on the top and bottom of the pulley assembly. The top bolt is easy to get to...unfortunately the lower bolt isn't. It takes some trial and error, and a whole lot of patience, to get it out; try loosening it from the bottom of the engine and then removing it from the top. Everyone's hand size and degree of flexibility is different, so it's just a matter of finding the right angle to extract it. We used a 3/8" 16mm socket wrench with a small extension to remove it...we found a 1/2" drive socket wrench too large and clumsy.
- The final part that needs to be removed from the engine compartment is the idler pulley. If the pulley has its center dust cover on, remove it with a small metal pick. Use a T50 torx bit to remove the center mounting bolt. Please note that this bolt may be very tight and require the use of a breaker bar.
Section 2 - Installing the New BMW E60 Tensioner Pulleys
- Installation of the new idler and tensioner pulleys is straight forward...just follow the steps above in reverse. Please note that the new tensioner pulley springs come pre-loaded out of the box - there is a pin holding them in the open position (DO NOT remove the pin yet) (see step 2b below). Torque all bolts to the following values: Tensioner Pulley - 18 ft-lb (24 Nm) Idler Pulley is 33 ft-lb (45 Nm)
- Once you have the three pulleys installed and torqued correctly, it is time to add the belts. Remember to always install the main accessory belt first...the AC belt is located on the outside of the engine and installed last.
- First, route the main accessory belt around and over all of the pulleys, as shown in the below diagram. Take your time and use patience...you are working in a confined space (if you get frustrated, take a break).
- The new belt tensioner pulley spring comes pre-loaded. In other words, there is a pin installed holding it in the "open" position so you can loop the belt over it.
- When you are satisfied you have the main accessory belt installed correctly over all of the pulleys, the final step is to remove the pin from the tensioner. This will require using both hands...one hand will turn turn the 16mm fitting clockwise to release pressure on the pin (just like in step 4 of the disassembly section above)....the other hand will remove the pin once the pressure is released. We know it sounds confusing, but it is actually quite simple. Watch the following video as we perform this procedure on our work bench:[video_embed url="https://youtu.be/lHKbcv7oaDQ"]
3. Install the AC accessory belt following the same directions in step 2 above.BMW E60 Tensioner Pulley Replacement Finished
