Belt squeak under load

[Exp21]

Hi everyone I recently did an enormous job on my w245 B-class CDI. I replaced pulleys, tensioner, belt, harmonic damper, etc. Now I noticed that in long curves while keeping the steering wheel turned (it's electrical and it happens especially to the left but I don't know why) I hear a squeaking noise from the vents, and I suppose it comes from the belt.
I have two hypothesis:
- when I installed the crank pulley I noticed a slight amount of wobbling but it could be an optical effect because it seems impossible that it seats non properly (torque is 200Nm+90°)
- the alternator pulley is going bad and with headlights on and electrical load the belt slips on it (alternator has 100k miles on it)

Do you think it's possible?

I used Contitech belt, Ina tensioner, it should be OEM quality parts, so I don't know where to look.

Thanks for help

 

[pgh13]

Can you pop the belt off and see if the noise is still there?

 

[Exp21]

Hi, not for now. I should lift the car and do the job. The problem is that it does the noise only when turning the steering wheel and with headlights on, at idle or going straight is almost imperceptible, if not present.

I think it's 100% from the belt, but I don't know what's the issue

 

[DREAMER NO2]

Loose belt . Is the belt slack?
Operate the headlight switch. If that causes a change in the squealing sound, then the culprit is the belt that drives the alternator.


Turn the steering wheel to full lock position either right or left. If that changes the sound, then the belt that drives the power steering is at fault try some belt dessing just to prove a point .,

 

[Exp21]

Hi, the car has electric power steering. So it's only an electrical current drain from the alternator. The belt is brand new, so it can't be loose. Thanks

 

[Uncle Benz]

Does it have a freewheeling pulley on the alternator? They often seize up, and what you describe fits with that

 

[Exp21]

Exactly. 3 months ago when I did the job I checked it by hand. The freewheel was noisy, but not stuck. It was noisy only stopping the pulley by hand. Probably if it makes more resistance than designed, the belt slips? Thank you

 

[Uncle Benz]

Yes, if it’s seizing up it makes the belt skip under load

 

[Exp21]

This was the noise of the freewheel: https://www.asuswebstorage.com/navigate/a/#/s/05578F8BA2774E6A994AFDA620AFFF974

 

[Snake Charmer]

That pulley sounds awful.

 

[Exp21]

I think it's time to do the job..again XD. Thank you

 

[Snake Charmer]

I think it's time to do the job..again XD. Thank you

Do you have the pully locking tool?

 

[Exp21]

No but I'll buy one, thank you. At 100k miles I'm asking myself if it's wiser to replace the entire alternator

 

[Snake Charmer]

Always a dilemma, especially if difficult to get at.

 

[W245207]

No but I'll buy one, thank you. At 100k miles I'm asking myself if it's wiser to replace the entire alternator

I had the same problem. When the alternator freewheel bearing goes, the engine sounds like a steam engine when idling.

I tried the rebuild route. Replacing the rear bearing, slip ring and the carbon brushes on the voltage regulator. This was all straight forward.

On these Valeo alternators' the front bearing is held by screws that are located from the inside. You will destroy the front cover if you try pressing out the shaft (corrosion). Moreover, the front bearing (larger) supplied have poor tolerance and the fit is 'loose'.

 

[Exp21]

Thank you! Probably we're talking of the same noise. At idle, from the cabin is barely perceptible, it's a light squeak.
I still have the doubt of the harmonic damper not properly seated, but honestly I don't know how it could be possible.
When noise gets worse I'll let you know if I solve it. Thanks

 

[Exp21]

I noticed something. The noise is like a hissing noise, like someone taking the last breath or trying to breath with asthma.
I think it's low AC refrigerant.

- But why it appears only when turning the steering wheel to the left?
It's systematic. I turn left and it appears.
- Car has 12 years. Do you think it's necessarily a leak or after these years it could be normal?

I also found this yellow drop under the condenser. What do you think it is?
AC works fine and it cools well.

Thank you for help

 

[ajlsl600]

Hi everyone I recently did an enormous job on my w245 B-class CDI. I replaced pulleys, tensioner, belt, harmonic damper, etc. Now I noticed that in long curves while keeping the steering wheel turned (it's electrical and it happens especially to the left but I don't know why) I hear a squeaking noise from the vents, and I suppose it comes from the belt.
I have two hypothesis:
- when I installed the crank pulley I noticed a slight amount of wobbling but it could be an optical effect because it seems impossible that it seats non properly (torque is 200Nm+90°)
- the alternator pulley is going bad and with headlights on and electrical load the belt slips on it (alternator has 100k miles on it)

Do you think it's possible?

I used Contitech belt, Ina tensioner, it should be OEM quality parts, so I don't know where to look.

Thanks for help

Give it a quick dose of Wd40 see if prob goes.
If so there's ur ussue seems prevelant when alt loaded, if tensioner on that not auto tensioning? If so was it a new mb pt or?

 

[Exp21]

It was a INA part. Equivalent to MB genuine part I think.
But the strange thing is that the noise is there only when steering left. And it seems coming from the vents, not from the belt. Thank you

 

[ajlsl600]

When you are on full lock the sreering is demanding a lot, I believe? Like stalling out the hydraulics and opening the relief on hydraulic steering. Try previous suggestion and see