Weird squealing sound from a 2006 BMW 318i

Verres

My car (an '06 BMW 318i) has started making a weird squealing sound.

It first happened a few weeks back and then it went away until yesterday. I reverse out of my drive way, and then when shift into first I can hear it (or that's when I notice it). It's quite noticeable / loud if you open the window.

It happens in all gears, at all speeds, and when stopped, out of gear idling and stopped in-gear with the clutch in.

The noise itself is a kind of metallic squealing. It's not a steady noise, as it pulses with the hum of the engine, and it jumps up a notch when I move off.

It's only happened twice, but each time it has disappeared after a few minutes driving. The car kind of jumps and the gear-stick noticeably shudders and then the noise is gone...

Any thoughts on what it could be? I'm not a gear head, but it seems like it could be serious. Thoughts?

barura

Sounds like the alternator belt to me. They squeeeeel when they get old.

Idbatterim

OP bring it to bmw specialist asap, something requires attention and better to do it before whatever it is, totally fails!

Nissan doctor

Your car is prone to auxiliary belt tensioner/guide issues,normally caused by oil leaking onto them from the rocker cover or chain cover.

dieselbug

The car kind of jumps and the gear-stick noticeably shudders and then the noise is gone...

Not familiar with these, just thinking dmf
What mielage and I presume its manual.

Verres

@dieselbug - mileage is very low for a 6 year old car - just 35,000km. Yes - it's a 6 speed manual.

@Nissan doctor - it's weird you say that because as per one of my posts some months back, I know I have a leaking gasket on the rockerbox (which I haven't bothered fixing as I wasn't losing any oil worth talking about), but could you explain what "auxiliary belt tensioner/guide issues" are? http://en.wikipedia.org/wiki/Tensioner explains kind of what it is, but I'm not really clear.

Something I need to get fixed, I assume? Also, what is a "guide"?

Thanks for the helpful responses, all!

Nissan doctor

Verres wrote: »

@dieselbug - mileage is very low for a 6 year old car - just 35,000km. Yes - it's a 6 speed manual.

@Nissan doctor - it's weird you say that because as per one of my posts some months back, I know I have a leaking gasket on the rockerbox (which I haven't bothered fixing as I wasn't losing any oil worth talking about), but could you explain what "auxiliary belt tensioner/guide issues" are? http://en.wikipedia.org/wiki/Tensioner explains kind of what it is, but I'm not really clear.

Something I need to get fixed, I assume? Also, what is a "guide"?

Thanks for the helpful responses, all!

The tensioner is a spring loaded(normally) adjustable pulley that keeps pressure on the auxiliary belt. A guide, or idler pulley, is a fixed pulley that is used to direct the belt around other parts etc.

A couple of diagrams from the interweb(not specific to your car:

http://www.google.ie/imgres?q=auxiliary+belt+diagram&hl=en&biw=1280&bih=709&tbm=isch&tbnid=F2k8VxZlK2EXOM:&imgrefurl=http://forums.justcommodores.com.au/vt-vx-holden-commodore-1997-2002/67031-diagram-required-routing-serpentine-belt.html&docid=OgLfPZ3GSJgxYM&imgurl=http://forums.justcommodores.com.au/attachments/vt-vx-holden-commodore-1997-2002/44176d1200653873-diagram-required-routing-serpentine-belt-drive-belts.jpg&w=1024&h=503&ei=Nlx9UOC2NY2LhQf5xoHwBg&zoom=1&iact=hc&vpx=326&vpy=82&dur=4231&hovh=157&hovw=321&tx=111&ty=51&sig=113316005300239211071&page=1&tbnh=135&tbnw=268&start=0&ndsp=25&ved=1t:429,r:1,s:0,i:66


If oil leaks onto the belt or the pulleys, which are mostly plastic on modern cars, they deteriorate and fail prematurely.

On the BMW, a leak from the front right(as you look into the engine) of the rocker cover leaks straight onto the auxiliary belt tensioner and its common enough for the belts to come off BMW's in this case.

Verres

@Nissan doctor - Is that as drastic as it sounds? Would it be serious cash to get it fixed?

Just wondering, because as soon as I bring it to a garage, it'll be 100 euros just to have a look...

Nissan doctor

Verres wrote: »

@Nissan doctor - Is that as drastic as it sounds? Would it be serious cash to get it fixed?

Just wondering, because as soon as I bring it to a garage, it'll be 100 euros just to have a look...

If that's the issue then you shouldn't be charged anything by a decent garage to check it as it will be pretty obvious.

Where are you based?

Verres

I'm based in Dublin - Blackrock...

Nissan doctor

Verres wrote: »

I'm based in Dublin - Blackrock...

If you want to venture over to the Northside I can look at it for you FOC.

Verres

Wow - that'd be great. FWIW, I drove it a lot over the weekend - (out to Ikea and back and down to wicklow and back) and there was no noise at all from it.

If it was the "auxiliary belt tensioner", would it tend to go away and come back, or would it be a constant noise? Just wondering as it might be a waste of a trip over to you.

But either way, it's most appreciated!

Nissan doctor

Verres wrote: »

Wow - that'd be great. FWIW, I drove it a lot over the weekend - (out to Ikea and back and down to wicklow and back) and there was no noise at all from it.

If it was the "auxiliary belt tensioner", would it tend to go away and come back, or would it be a constant noise? Just wondering as it might be a waste of a trip over to you.

But either way, it's most appreciated!

It depends, it can certainly come and go in the earlier stages. An issue would still be obvious though of there was oil leaking onto the belt.

If you want to head over just give me a shout.

Verres

Thanks - It's really appreciated. I'll PM you.

Thanks again