Help with 2003 BMW 325i - Noisy Belt

[yrod]

Hi everyone,

First of all, I'm new to the forum. I just bought a 2003 BMW 325i used. The car has about 92k miles on it. Just did an oil change. However, whenever I start up the car, it makes this really squeaky noise. Any help and advice would be greatly appreciated.

I've included video so you can hear what I'm talking about. I also included a few pictures. In one of the pictures I labeled one of the belts, which I noticed is cracking. Does anyone know what this belt is?

Also, I was wondering if anyone can tell me if this car has a timing belt or a timing chain. Doing some research, I concluded that my car should have a timing chain, but I'm not sure if you guys can tell from my pictures.

Thanks in advance!

[WoLF]

That belt is done! Replace ASAP

[E46 Dude]

Yes the belt you referenced is the tensioner belt also get the ac belt since your there also you will want to replace idler & tensioner pulleys to cure the squeaking... There are many DIY videos on YouTube I just did this myself... If you have an auto trans you will need the special fan removal tool...

[hitbyastick]

Engine has a timing chain not a belt, but you can't see it because it's inside the front of the engine. The parts you need to replace are the accessory belts, one short and one long.

[yrod]

Yes the belt you referenced is the tensioner belt also get the ac belt since your there also you will want to replace idler & tensioner pulleys to cure the squeaking... There are many DIY videos on YouTube I just did this myself... If you have an auto trans you will need the special fan removal tool...

Thanks, by tensioner belt do you mean the serpentine belt? Maybe I'm looking at the diagram wrong, but to me it seems the one that's cracking is the A/C belt not the serpentine belt...?

Do you know how to figure out which pully - idler or tensioner - is making the noise? I took it to a mechanic and he said that he could figure it out, but of course I'd have to shell out 70 bucks.

[yrod]

Yes the belt you referenced is the tensioner belt also get the ac belt since your there also you will want to replace idler & tensioner pulleys to cure the squeaking... There are many DIY videos on YouTube I just did this myself... If you have an auto trans you will need the special fan removal tool...

Thanks, what do you mean by tensioner belt? Do you mean serpentine belt?
Also it's strange because based on my picture and the diagram, it seems that only the part of the serpentine belt that is wrapped around the tensioner is cracked, not the other parts of it...Is that normal?

[yrod]

Also a related question -- is there really no way to figure out if I have a hydraulic or mechanical tensioner without actually taking out the fan and everything? It seems that while it's very probably I have a hydraulic there's no way to really know without opening it up...

[yrod]

Also I meant to submit a post thanking everyone for the responses/help thus far, but apparently it's being reviewed by mods...

[hitbyastick]

You might be able to use a telescopic inspection mirror to ascertain mechanical vs hydraulic. Not really possible otherwise with all the stuff in the way. May also be possible to see the bottom tensioner pulley from below the car with the splash plate removed. When I replaced the cooling system I finally could see what I had, one mechanical and one hydraulic. Both original to the car and both working fine.

[yrod]

You might be able to use a telescopic inspection mirror to ascertain mechanical vs hydraulic. Not really possible otherwise with all the stuff in the way. May also be possible to see the bottom tensioner pulley from below the car with the splash plate removed. When I replaced the cooling system I finally could see what I had, one mechanical and one hydraulic. Both original to the car and both working fine.

My dad suggested I call a local BMW dealer, give them my VIN and see if they have the info in their system. I don't know if they'll be so nice, haha.

How many miles do you have on your car? Mine is at 92k, and I wonder if it's expected that the tensioner will start making noises at that mileage.

[yrod]

Yes the belt you referenced is the tensioner belt also get the ac belt since your there also you will want to replace idler & tensioner pulleys to cure the squeaking... There are many DIY videos on YouTube I just did this myself... If you have an auto trans you will need the special fan removal tool...

Thanks for the info. My mechanic also said it wasn't likely that the belt was causing the squeaking, but rather either the idler or tensioner pulleys - I'm not sure which.
Did you replace both your idler and the 2 tensioner pulleys? Do you know which one was causing the squeaking or were they all making some noise? I'm just wondering if I should replace all of them...

[E46 Dude]

Yes replace everything at one time it is much simpler to know you are good to go for another 60k-100k without changing them as they fail one by one... And they really aren't that expensive... The belt may not be making noise but from your pic that thing isn't far from snapping due to age and cracking in the rubber... You don't want to be stranded...

[fraternalpig]

The mechanical tensioner is a giant silver can-looking thing and the hydraulic one is a hydraulic shock and some linkage, so it'll be easy to tell the difference. Make sure you spin all of your pulleys when you have the belt off to check for any play or notchiness. And if your waterpump is nearing 100k miles, might as well do that, the expansion tank and the t-stat while you're in there and get it all out of the way.

[legoman67]

replace the tensioner, idler and belt at the same time, while your in there check your water pump and thermostat housing.

[yrod]

Great, thanks for all the help guys.

A few more questions:

1) I was at the BMW dealer today and found out that both of my tensioners are the hydraulic type. I was reading on this last night and people were saying that the hydraulic tensioner rarely breaks. Does this mean I only need to buy the pulleys and not the tensioner? Autohausaz sells the alternator tensioner as a tensioner/pulley assembly, but I think I can get them separately on pelicanparts.

2) Do I need to buy protective caps for my pulleys? I think the parts guy at the BMW store mumbled that I didn't need to but I didn't ask to confirm. I just noticed that all the online parts merchants sell the protective caps separately.

TIA!

[yrod]

replace the tensioner, idler and belt at the same time, while your in there check your water pump and thermostat housing.

what exactly should i be checking for when i check my water pump and thermostat housing?

[E46 Dude]

what exactly should i be checking for when i check my water pump and thermostat housing?

Any leaks, play, or noise from water pump and cracks in plastic thermostat and expansion tank... The caps are reusable so unless yours breaks you should be good on those unless you like to prepare for the worst and have one on standby if needed.

[yrod]

Any leaks, play, or noise from water pump and cracks in plastic thermostat and expansion tank... The caps are reusable so unless yours breaks you should be good on those unless you like to prepare for the worst and have one on standby if needed.

Thanks, btw, did you have a hydraulic or mechanical tensioner? I have a hydraulic one. Is it true that I probably just need to replace the pulley and not the tensioner?

[E46 Dude]

Yea should be fine just replacing the pulley that is on the tensioner...