2004 645ci Squealing Fan Belt when car is cold..?? - Bimmerfest - BMW Forums



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E63 / E64 6 Series (2004 - 2010)
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  #1  
Old 08-03-2019, 10:00 AM
Mikesett Mikesett is offline
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2004 645ci Squealing Fan Belt when car is cold..??

Hello All, Ive got a 2004 645ci thats in very good shape. About a month ago I brought it in to have the alternator changed and and a coolant hose changed out.

While it was there the mechanic recommended I change out the fan belt as well because it was squeaking and squealing alot.

So I did this and had him change the belt. Directly after this I left the car parked over night, and when it was cold in the morning, upon start up? It was squealing even worse than before he changed it.

It only squeals though when the engine is cold (like in the morning upon first start for the day), and then as the engine warms up the squealing gradually goes away. Once the engine is hot? It barely makes a sound..Maybe just a little chirp here or there..

But in the morning its crazy loud and really embarrassing at this point..Makes the car sound like a jalopy and it squeals like a stuck pig..Its really really aggravating me at this point..

Does anyone have any experience with this or any suggestions? Now that ive changed the belt im not sure what else to do..Especially confused because it only makes the sound when its cold..

Any advice would be greatly appreciated..
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  #2  
Old 08-03-2019, 11:54 AM
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Hsurf Hsurf is offline
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Did your mechanic also change the tensioner when doing the serpentine belt? Also are you 100% sure it's this belt and not the A/C belt on the left or the water pump which is just above? All three can make a squealing noise just different pitches and volumes.
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Old 08-04-2019, 05:11 AM
Mikesett Mikesett is offline
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Originally Posted by Hsurf View Post
Did your mechanic also change the tensioner when doing the serpentine belt? Also are you 100% sure it's this belt and not the A/C belt on the left or the water pump which is just above? All three can make a squealing noise just different pitches and volumes.
Thanks for your reply..The mechanic did not change the tensioner. Maybe this is the issue. Also the car does not have a an AC belt at this time (long story), but yes possibly the water pump belt could be the culprit too. I'm going to have them check the tensioner and that belt. Thanks!
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Old 08-04-2019, 12:47 PM
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Hsurf Hsurf is offline
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The water pump doesn't have a separate belt, it's powered by the same serpentine belt you've had replaced, when the pump wears it can create a squealing noise. If the pump is the original then it will have a plastic impeller inside which can break up and send bits through the cooling system, it doesn't often happen so don't go into panic mode it's just a known fault, it's quite likely the tensioner, if you roll the pulley with the belt off and it just spins and spins then it will want changing, it should have some slight resistance and feel smooth when rolled if its good it should only turn around half to a full turn when you roll it with your finger .
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Old 08-04-2019, 12:54 PM
Mikesett Mikesett is offline
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Originally Posted by Hsurf View Post
The water pump doesn't have a separate belt, it's powered by the same serpentine belt you've had replaced, when the pump wears it can create a squealing noise. If the pump is the original then it will have a plastic impeller inside which can break up and send bits through the cooling system, it doesn't often happen so don't go into panic mode it's just a known fault, it's quite likely the tensioner, if you roll the pulley with the belt off and it just spins and spins then it will want changing, it should have some slight resistance and feel smooth when rolled if its good it should only turn around half to a full turn when you roll it with your finger .
Ahhh I see, ok..Thanks a million for your help. Its sounding more and more like the tensioner is probably the culprit here..Any idea though why the engine temperature would affect if the belt squeals, if it is the tensioner thats bad? Thats the confusing part of this for me, because as soon as the engine gets warm the squealing stops..
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Old 08-05-2019, 07:02 AM
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Hsurf Hsurf is offline
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That's at least part of the reason I mention the water pump, as things heat up and expand inside excess tension is taken up thus stopping the squealing, the same is also true of the tensioner however, being directly bolted to the block it too gets pretty warm thus expanding the internals of the pulley its just to a lesser extant than that of the water pump.
If you leave it too long the noise (where ever it's coming from) will last longer and longer until its constant regardless of the temp, at that point things can all go a bit pete tong , your on it early and that's a good thing and if you still have problems then a mechanics stethoscope can go a long way to isolating problem noises like these they're also dirt cheap .
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Old 08-05-2019, 12:29 PM
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As HSurf mentioned treat yourself to a mechanics stethoscope and you will find the culprit in seconds, just be careful around moving parts,
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Old 08-06-2019, 10:47 AM
Mikesett Mikesett is offline
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Quote:
Originally Posted by Hsurf View Post
That's at least part of the reason I mention the water pump, as things heat up and expand inside excess tension is taken up thus stopping the squealing, the same is also true of the tensioner however, being directly bolted to the block it too gets pretty warm thus expanding the internals of the pulley its just to a lesser extant than that of the water pump.
If you leave it too long the noise (where ever it's coming from) will last longer and longer until its constant regardless of the temp, at that point things can all go a bit pete tong , your on it early and that's a good thing and if you still have problems then a mechanics stethoscope can go a long way to isolating problem noises like these they're also dirt cheap .
Well, it was the water pump..Blew out on me on the parkway last night ***x1f615;..Wound up being a $950 job to replace it and fix everything else it messed up when it blew..Definitely should have brought it in sooner to get it checked out..Lesson learned lol..Thanks for all the advice though buddy ***x1f44d;***x1f3fb;
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Old 08-07-2019, 10:28 PM
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Hsurf Hsurf is offline
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Originally Posted by Mikesett View Post
Well, it was the water pump..Blew out on me on the parkway last night ***x1f615;..Wound up being a $950 job to replace it and fix everything else it messed up when it blew..Definitely should have brought it in sooner to get it checked out..Lesson learned lol..Thanks for all the advice though buddy ***x1f44d;***x1f3fb;
Sorry to hear that mate, I was hoping you had caught it early enough but I guess not, what else had to be replaced?
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