DIY X5 35d idler pulley and belt tensioner replacement guide

Mr.47 · Dec 6, 2016

This is a ENTHUSIAST DIY GUIDE not meant to replace a ORIGINAL BMW SERVICE MANUAL , im no way responsible for damages or injuries or death because you followed this guide perform this at your own risk.

This was performed on a 2011 BMW X5 35D with 74k miles,

So my X5 35d was started to make some horrible loud whining noise that increased pitch/loudness congruent with engine RPM, also some rattle like noise around 1500 rpms, here a clip of it making a racket!

https://www.youtube.com/watch?v=n3SireTZUlA

At first i had no idea where this sound was coming from i begin to test by first removing the belt and securing it somewhere safe and started the engine, no sound so its down to the alternator, power steering or A/C or pulleys, so i took out my automotive stethoscope, with the belt on and engine running i poked around and pinned point to the idler/deflection pulley that is been a culprit.

So what do you need

1 Deflector/idler pulley at $26~
1 Pulley tensioner at $65~
Tool Set
Serpentine belt tensioner tool ($17.99 at Harbour freight)
Extra Long screwdriver (optional very handy)

First remove the support bar, 4x 13mm bolts holding it then carefully slide it to the right (towards driver side) and lift up the left side of the bar and remove it

Remove the charged air hose bracket that is attached to the radiator fan shroud, theres a Torx screw holding, after remove torx screw some manipulation is required to unhinge the hose bracket take care not to break the mounting point!!

Next remove the charged air hose to intake manifold, use screw driver to remove the top clip then bend hose to the side let the hose rest against the throttle body housing, watch out for electrical wires!!

Remove the electrical plug on the radiator fan, push the 2 release clips on each side of plug and pull

Coolant fan removal

Remove the 2 small coolant hose that are held in by fan housing, see picture (orange box are hose securing clamps, one in the middle and one at the bottom) you must remove these first before attempting on lifting the fan.

To remove the coolant fan there a 2 clips on each side, push in the tabs to release and gently pull up slightly to unclip from mount DO NOT ATTEMPT TO REMOVE YET!!!

Left side (US passanger side) (red arrow show direct to push in the clips)

Right Side (US Driver side) (red arrow show direct to push in the clips)

RIGHT SIDE MOUNT!!!
On the right side the mount the fan mount is hinged, MAKE SURE THE RIGHT SIDE IS NOT MOUNTED AND LOCKED IN!!! take a screwdriver and pop it up

Move the mount hinge away from the upper radiator hose and the fan can be removed safely

Mr.47 · Dec 6, 2016

Remove the radiator fan, make sure the hose is not caught in it and slowly and gently pull it up, the charged air hose going to the intake manifold may get in the way just work the hose around, after the fan is out you'll be rewarded with lots of SPACE TO WORK! :rofl:

Next remove the drive belt, get your serpentine belt removal tool with a 19mm deep socket or small extension is needed if your using and standard socket

Stick it on there and turn counter clock wise (ie left) all the way and slide off the belt from tensioner pulley

Tensioner Removal Pt 1

Now you need to lock the tensioner into its position in order to access the bolts that holds the belt tensioner. Grab your self a drift, dill bit or allen key, use the serpentine belt tensioner tool turn it counter clock wise (left) while insert the allen key, when the key drops in place slowly release tension.

Here's a closer look of where the tension lock hole is at, with allen key in it

In Order to access the upper bolt of the tensioner you need to remove the idler pulley

Idler pulley removal

On the idler pulley remove the dust cap to expose the bolt, use a long reach flat screwdriver get behind the dust cap clip and pop it off.

Then take a 6mm allen head socket and remove the bolt, these are standard bolt (NOT REVERSED THREADED!!) counter clock wise to remove

Tensioner Removal Pt 2

After you remove the idler pulley you can now access the 2 Torx bolt (i forgot what size it was

)
Arrow shows location

Bottom are alittle tricky

Removal of the whole tensioner assembly can get a little finicky because of the small radiator hoses that are blocking it.

Trick is to carefully turn the tensioner counter clockwise until the pulley is down, picture shows where it should be and how to turn it

Onces the pulley is pointing downwards you have just enough clearance to remove the whole assembly, you may need to slightly bend the radiator hose around to get it out be careful not to bend too much or you may risk breaking the plastic splitter coolant hose, 5 yrs old plastic parts are as sturdy as a fragile glass

Reassembly

To install the tensioner assembly perform in reversal when you remove the old , slot it in with the pulley pointing down towards to the floor, then slowly turn it clockwise while watch and manipulating the coolant hoses, careful not to break the plastic coolant splitter!!

Reinstall the bolts, tip use some tape to preventing the bolts from falling down and torque them to 8 NM

Reinstall the idler pulley inspect that you have a new bolt, front dust cap and a rear metal dust cap, install the pulley and torque to 30 NM

FRONT

REAR

Reattach the belt this may get tricky and messy be warned!

Fan installation, take the fan and slowly slide in it in watch for the right hinge part make sure its not in the way, and watch for the small radiator hose make sure your not crushing it or cutting it and onces you get it in make sure the hoses are in its perspective clips and that the radiator fan its lock in its mount (especially the right side make sure the hing it fully extended after passing the upper radiator hose) and plug in the fan!

Reinstall the upper support bracket, snug tight (not sure about torque spec)

Mr.47 · Dec 6, 2016

(reserved)

bibsun · Jan 2, 2018

Hi should the belt tensioner assembly come straight out once the two hex bolts are removed ?

Sent from my B3-A40FHD using Tapatalk

FredoinSF · Dec 6, 2016

Awesome write up. Subscribing to thread in case needed in future.

ChrisM011 · Dec 11, 2016

Very nice! Thank you!

stevieg58 · Dec 11, 2016

Great job with this:thumbup:

In order to spread the great information, I edited a post I made in the past on thermostat replacement for the 35d to add a link to this post. Your description is much more detailed than mine on how to remove the fan. I know this will be helpful to a lot of people.

Thanks again.

Thirdy · Dec 27, 2016

seems like I might be replacing mine soon. I have a whine coming from the engine pretty much the same sound like your youtube clip. It goes with the rpm. This will be a great help. Thanks

ajmal · Jan 18, 2017

hi Mr.47, this is a great write up, i have an major issue and could not find anything online, i have the exact same car the idler pulley bolt broke right off from the place it supposed to be half of it is in the alternator and the other one is at the bottom of the car fallen down.

my question is. is the idler pulley only connected to the alternator or is it going trough the alternator into the engine. it seems pretty short screw. and how do i take out the alternator?

i would really appreciate if someone answered this question, because taking it to bmw would cost alot of money.

stevieg58 · Feb 11, 2017

The bottom bolt holding the alternator in place has an internal threaded end. This is what the idler pulley bolt screws into. If the idler pulley bolt has sheared off you will probably need to replace both the alternator bolt, and the idler pulley bolt.

audiojack · Apr 19, 2017

Thank you Mr. 47. I performed this on my '11 x535d without any complications due to your helpful write-up. In my case, the deflection pulley was the culprit since the tensioner was recently replaced. The sound from the bad deflection pulley was identical to your YouTube clip.

Andras888 · Nov 29, 2017

Thank you Mr.47 for the detailed guide. FYI, I was able to replace the idler pulley without removing the fan, and release the tensioner with a regular 1/2" breaker bar. Thanks again!

08-730d · Dec 23, 2017

Great job and nice thread.
I guess you didn't´t replace the serpentine belt as you did not remove the ac belt. Have anyone on here changed the ac belt? I recall reading that there isn´t a tensioner, so you´d have to use a special tool to get the belt off (and back on..).

SoCaLE39 · Dec 25, 2017

That is correct I've heard people say it's not an issue which others struggle to replace that belt. Also, BMW later shortened the belt slightly as people were experiencing belt squeaks. As for the tool it can be easily found on Amazon for I think $20.

08-730d · Dec 26, 2017

Thanks, just ordered one from the bay´

Badsmerf · Jan 10, 2018

Add me to the list. This morning the alternator bolt snapped. Getting a new one and a new idler bolt for good measure. Anyone have the torque value for the alternator bolt? I usually don't care about torque to much, but it's better to know than not.

Andras888 · Jan 10, 2018

Badsmerf said:
Add me to the list. This morning the alternator bolt snapped.

How could that bolt snap? Did one of the bearings of one of the pulleys freeze?

Badsmerf · Jan 10, 2018

Already been done. I'll get the tensioner set and get the bolt out tonight. Should be a pretty easy fix since my belt is still in place. Had this happened somewhere besides my driveway.....

Kyonkanno · Feb 8, 2018

Thank you for the guide! although I have a 30d, the tensioner pulley is exactly the same and the process was the same. I had the same whiny noise and now it's gone!

I gotta mention that those pulleys are kinda mystical in how they fail. Upon inspecting the old pulleys from my car, they look in good shape and the pulleys turn with about the same resistance of the new ones. I could have made some tests to see if my old pulleys were serviceable but I'm not too excited about taking them in and out multiple times just out of curiosity.

Alpinerunner · Nov 2, 2018

Great writeup! Helped me a lot. One note I'd add is to remove the lower tensioner bolt first, then release the pin/allen key from the tensioner, because once you remove the bolt behind the idler pulley, you'll no longer be able to torque the large nut to release the pin, and the pin will hit the radiator before the rod is out of the engine.

Mark Parker · Jan 19, 2019

I'm new to the forum a new owner of a 2012 BMW X5 35D as of 2 days ago. This is my first BMW.

All of sudden I have the Whining noise just as the video posted. I was given by the seller that there is another recall on the pulley but BMW has not come up with a solution and it maybe July of this year before they do and start the recall. I really do not want to spend a bunch of money replacing all of these parts since there is going to be a recall but I don't think I can deal with all the noise under the hood. Is there a way just to replace the pulley itself without taking off and replacing the pulley tensioner? Was it the idler pulley making all the noise and can this be replace easily by a mechanic without disassembling as in the article above?

Thanks.

Alpinerunner · Jan 21, 2019

Mark Parker said:
I'm new to the forum a new owner of a 2012 BMW X5 35D as of 2 days ago. This is my first BMW.

All of sudden I have the Whining noise just as the video posted. I was given by the seller that there is another recall on the pulley but BMW has not come up with a solution and it maybe July of this year before they do and start the recall. I really do not want to spend a bunch of money replacing all of these parts since there is going to be a recall but I don't think I can deal with all the noise under the hood. Is there a way just to replace the pulley itself without taking off and replacing the pulley tensioner? Was it the idler pulley making all the noise and can this be replace easily by a mechanic without disassembling as in the article above?

Thanks.

Yes you can just release tension from the tensioner pulley, remove the belt, and replace the idler pulley. You do have to remove the electric fan, which is probably the most annoying part of the job. I believe the recall is for the idler bolt, but I'm not sure. Anyway, I wouldn't be surprised if the recall just replaced the bolt, and not the pulley so it's probably worth replacing the pulley anyway. That being said, my pulley squealed for a good 6 months without issue before I replaced it (along with tensioner, belt and water pump.

busrider · Mar 17, 2019

DIY Tensioner reality

In a perfect world, your Tensioner Pulley replacement should go exactly as described in this well done thread.

In reality, be aware of what can and does happen sometimes during this exercise.

My 2012 X5 35d has 180k showing on the clock. While replacing the EGR valve & Cooler, I decided to also replace all of the Belts, pulley's, Water Pump, Thermostat, etc.

Even with the Torx bolts removed, the tensioner assembly was frozen in place.

A little coaxing can result in the scenario you see in the photos - a guide tube that is still firmly frozen in place and a handful of Tensioner guts.

I hope this doesn't or hasn't happened to anybody else. If it has then I would greatly appreciate knowing what you next step was/is. I'm fairly certain I know what the next step is for me but I would love to hear from somebody who may have some time saving recommendations after experiencing the same.

Let the fun begin ...

SPL15 · Mar 19, 2019

busrider said:
In a perfect world, your Tensioner Pulley replacement should go exactly as described in this well done thread.

In reality, be aware of what can and does happen sometimes during this exercise.

My 2012 X5 35d has 180k showing on the clock. While replacing the EGR valve & Cooler, I decided to also replace all of the Belts, pulley's, Water Pump, Thermostat, etc.

Even with the Torx bolts removed, the tensioner assembly was frozen in place.

A little coaxing can result in the scenario you see in the photos - a guide tube that is still firmly frozen in place and a handful of Tensioner guts.

I hope this doesn't or hasn't happened to anybody else. If it has then I would greatly appreciate knowing what you next step was/is. I'm fairly certain I know what the next step is for me but I would love to hear from somebody who may have some time saving recommendations after experiencing the same.

Let the fun begin ...

Ouch! That's a rough one...

Just did all of mine this weekend; however, the tube was completely clean & dry, so came out without any issue. Bearing was worn out, causing a low pitched howling noise. After seeing these photos, glad I sprayed the guide tube on the replacement tension assembly w/ an anti-corrosion spray before I stuck it back in...

If I were in your situation, I'd spray a bit of penetrating oil on it everyday for a few days, as the photos show a lot of corrosion on all the metal in that photo (possibly from lots of messy DEF refills, or a LOT of salt / chemical spray from roads, with no PM to clean it off, for a long time...)... Hopefully it creeps into it a bit where you're eventually able to twist the rod with a pair of vice grips to loosen things up.

If that fails, I'd start taking the front bumper assembly off, and everything else needed to get the radiator out, in order to grab the guide tube from the front & allow pulling it axially. Slide hammer would likely be needed as well... You're going to need to break up the corrosion somehow, as I doubt you'll be able to budge anything with things dry...

When I took mine out, there "felt" to be around 0.050" or so radial clearance between the guide tube & the bore in the block... If the corrosion byproducts are bad enough to where they've expanded & are pressing against the guide tube, it could very well take extreme measures to remove it.... Your best bet is to start the process of softening / rehydrating all that dry corrosion byproduct, & then go from there...

What a pain... Folks would be wise to clean & degrease their engine compartment on a regular basis, as well as not spill DEF all over the place...

blue dragon · Mar 17, 2019

Anyway to get some heat on the guide tube? I'm assuming it metal

x5dieselwhite11 · Jan 22, 2021

just a query, what are the parts no. of the idler pulley and pulley tensioner bmw

Doug Huffman · Jan 22, 2021

RealOEM.com

Nonsuch · Nov 6, 2022

Not an answer to the prior post, just a general update:
It’s been a few years since this thread was bumped, and the idler pulley has been redesigned (again). A single long bolt goes through the pulley and a spacer, and also secures the alternator (SI B12 19 18)

wiscobmwe90 · Feb 4, 2024

Thank you much for the updated recall link! Recall had been done a few years ago on my 35d, but when I received the parts yesterday I noticed the new bolt spacer and couldn't find much info on it. Replacing pulley, tensioner, and both belts later today.

busrider · Nov 9, 2022

My situation seem to be extreme. I was forced to replace the power steering pump bracket. The tensioner pulley guide tube plugs into a cylindrical guideway within this bracket. Due to corrosion, the tube was frozen inside the bracket.

There is no option at this point. You have to replace the bracket. Replacing just the bearing in the pulley wheel will buy you some time but eventually the tensioner pulleys alignment will begin to fail and you run the risk of throwing the belt.

Regardless of how easy or severe your particular situation is, remove the radiator fan before you do anything. You'll thank yourself for doing and it's a simple exercise.

If it appears that you have a situation where parts are frozen, remove the alternator next. You will eventually need that extra room and the accessibility it will then afford, too.

Good luck.

07E93Hardtop · Feb 8, 2023

Super helpful! (changing alternator) getting room to work is a HUGE thing... !

E46jur · Apr 29, 2024

Just wanted to add for anybody that runs into the tensioner being stuck just jump to pressing it out. I ran into this issue (was aware it can happen) on an engine that I was working on a stand. Tried every possible way to get it out with the bracket still mounted to know if it's possible to do without a bunch of disassemble with an engine in the vehicle. Nothing worked. Don't waste your time. If you don't own a press harbor freight has a 12ton $170(cheaper than the bracket if you have the space for one). If not any shops in you're area will definitely press it out if you slip a mechanic a couple bucks.

DIY X5 35d idler pulley and belt tensioner replacement guide

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