Squealy Noise W124

[JonathanC]

Hi All

My 93 200E has developed a kind of squealing noise that eminates from under the bonnet. It sounds like a slipping fan belt but doesn't follow the normal pattern for a slipping fan belt, i.e. doesn't always squeal under acceleration or with increased load on the fan belt. It seems to be inconistent when it happens ( or I haven't identified a pettern) and can be heard at standstill if revved to about 1500 rpm or 2500 rpm. It can be quite loud at times.

The only other sympton appears to be a constant noise squaly/whoosh sound at about 60 mph that goes away after about 65mph. This is not engine speed related but does go away if you lift off the gas.

I have changed the poly v belt and whilst doing this spun all the pulleys/pumps alternators and everything seemed to spin OK but on refitting new belt the noise is still there. I am now at a loss as to what it could be and have even laid under the car to try and identify it. Closes I can get is the noise is coming from the off side of the engine bay, apparently close to the bulkhead and low down.

Did several searches but haven't found anything that seems to specifically relate to this noise.

Does anyone have any ideas what this might be? It's drving me mad!! :?

Thanks

 

[grober]

Squealing noise.I think this maybe the sound you get from your alternator when it is under load/charging. Not anything to worry about. Try listening for it after driving a few miles and the engine is warmed up and battery charged up with no load- lights heated screen aircon etc on. cheers G

 

[JonathanC]

Thanks Graeme

Unfortunately this is a new noise and is so loud people look as you drive by!

Turning on/off heated rear screen, lights etc has no effect so not directly related to charging as far as I can tell. Turning on/off air con to increase/decrease load on v belt has not effect either. I know this will be something obvious to someone but I am bu**ered if I know what it is!

Cheers

 

[mjtray]

If its quite a high pitched squeel it could be your alternator bearing that is on its way out.....id it worse when you first start from cold...ie when all of the electrics are under load?

Alternatively, if its a sort of rubbing/whooshy sound, it could be the vibration damper thats on its way out...to check this...open bonnet, look down behind the left hand side of the radiator at the drive belt. Attached to the front of the engine block is the belt tensioner and beneath this is the vibration damper.....on your modelit may ve slightly different. If its on its way out the pulley will be slightly out of alignment to the drive belt which will cause it to rub.

If its this you will need a new vibration damper....not that easy to change as the hub bolt is held on very tight....221 lb ft. If left to slowly deteriorate it will eventually throw the belt.

 

[JonathanC]

Thanks mjtray.

Alternator seemed to spin quite happily when I changed the belt so not obviously a problem but I gues I can't spin it at 1500 rpm so it may be the problem. It doesn't seem to follow a pattern, i.e. not related to engine speed, load, temperature, weather or electrical load. The only other thing I can think of is something vibrating but it doesn't sound like that kind of noise and I have been under the card and checked.

 

[mjtray]

Which side of the engine bay is the noise coming from....can you try an isolate it?

 

[JonathanC]

Diffficult to isolate as it is hard to get it to be constant. Appears to come from the drivers side, perhaps around the sterring box area? I first suspect heatshiled loose but haven't been able to prove this. I guess the alternator is on this side so could still be prime suspect. I think I will remove the belt and run the car briefly to confirm if it is something driven by the belt or not. I'll post the results once done,

Cheers

Jonathan

 

[Gavin450slc]

could it be...

a leaking head gasket?? I don't suppose you've noticed any loss of power or mixed fluids have you?

I have had a head gasket go, which sounded like a fan belt slipping (kinda).

If you have a compression tester - may be worth a quick run down - if only to discount it.

Gavin.

 

[JonathanC]

Didn't think about head gsaket - haven't noticed any mixed fluids or loss of power but I will check. It did occur that it might be an exhaust leak but it isn't consistent and doesn't change with temperature.
Thanks

 

[JonathanC]

Update:

The car is now making squealing sounds all the time and reading replies to my post and others it seems the alternator bearings are most likely to be the culprit so its new alternator time.

I have just been on to German and Swedish and had an odd conversation with one of their staff. Without boring you with the details, is the alternator for a 2l M111 engine the same as the 6 cylinder engines (M103?) and what output should it be?

Thanks

 

[dieselman]

If it's the bearings then why do you need a new alternator, just buy the bearings from your local supplier or alternator reconditioners. It will be probably be the nose bearing and will cost about £3-£5.

 

[JonathanC]

Dieselman - Good idea, I assumed that it would be a difficult job to change the bearings hence going the easy route. Also, as the car is on 160k I thought it might be prudent to get a new unit. Are the bearings easy to change and easily available ?

Thanks

 

[sunking101]

Hi, did you ever get to the bottom of this screeching/squealing noise?
My 190 has started doing it but only when starting from cold and usually only on a damp or wet day. The problem is getting worse/louder and more regular though and as I do a lot of 250 mile motorway journeys I'm worried something is on its way out. I'm convinced the noise is coming from the belt/pulley/pumps region. Has anyone else got an idea what it might be? Thanks in advance.

 

[PINBALL]

Had the same problem last year on a Volvo!

Squeeling came n went at varying intervals, hot or cold / hi rev or low, didn't make any difference to it ...

Turned out to be the alternator, but not the bearing!!! and alternator worked n tested fine.

So, what was it, I hear you say ...

It was the bracket that held the alternator under tension against the belt that had a hairline crack in it which caused it too loosen against the belt when car was in motion only.

The clever Volvo tech put it on a rolling road (used for MOT braking test) and held a flashing scope to it which showed up the crack-flexing problem!

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Just one other thing that others had said it might be was the water pump could also cause this problem.

Hope it helps.
Keith.

 

[JonathanC]

Sorry, I should have let you know the solution. It turned out to be a broken exhaust bracket. This let the exhaust downpipe move which rubbed against the joint to the manifold giving the squealing sound. Never would have got this until I got it onto a ramp then it was obvious. £10 part fixed the noise, which was good as I was about to sell her!

Cheers