[mercedesbenz911]

Car was on the last leg of a 300 mile trip when this noise began. It varies with RPM. Oil is clean and full (just changed today). Sounds like a belt noise? Maybe some accessory bearings going out?

 

[humblejoe]

tough one

videos are always tough for me to guess, but It sounds like a puckety puckety noise, ie compression of something. Does it make the noise with climate off? (rules out a/C compressor) other compression sources are smog pump, and of course engine compression.
Sorry, not real good with noises unless I can hear them first hand

 

[mercedesbenz911]

A/C is off.

I found these entries in the service history relating to a noise:

March 14, 2009 - 139,247
Customer states clicking sound under hood.
Found bearing on bearing bracket had come apart, R&R engine belt and fan, replaced bearing bracket along with pulley (pulley rubbed against housing).
1 104-200-13-28-88 Bearing bracket
1 104-205-02-10 Pulley
1 012-997-51-48 Seal Ring

and...

November 14, 2008
Noise on cold start.
Check for noises; replaced secondary air injection pump.

 

[Clarkz71]

With the noise being that loud, pull the belt off and spin each
component by hand (engine off of course) You'll find it.

If everthing is OK start the car with the belt off, noise gone one of
the accesories is bad. Noise still there, internal engine issue.

 

[mercedesbenz911]

Okay...I have a very basic problem. I can't even get the belt off! How do you release tension from the belt? Mine looks nothing like the one in the FSM (attached). It's not spring loaded like the M119 either. I see neither a spring nor an adjustment bolt like the FSM. I've looked top and bottom for some sort of adjustment bolt but found nothing.

 

[Clarkz71]

Take a pic & post it. Then we can see which tensioner you have.

The one in your pdf is the manual one.

But, back off my mpg claim.................jk

 

[mercedesbenz911]

Not much room to get a camera in but this is what I managed:

 

[cbc atl]

This version looks a little different. Seems you have the later version and you may have to remove the viscous fan clutch then swivel the tensioning pulley to get that belt off.
http://www.w124-zone.com/downloads/MB CD/W124/w124CD1/Program/Engine/104/13-1200.pdf

I guess it is possible to get a wrench on it without removing the fan if you have the right one. Anyway you have to make it swivel by turning it clockwise to remove tension from belt.

 

[Mercedes mechanic]

Sound's terrible. From lack of visible metal shaving around the outside bearing's, I would say stop running the engine.

You may just need to replace the chain or phaser.

That noise is too loud to be on the outer pulley's.

 

[KMani1]

I had 95 E320 with M104 that sound like the aux-airpump. Try disconnect the electrical wire to that airpump so the clutch won't engage during start up, it usually use only cold first start up to supply air to the exaust to catalitic converter to heat up faster. I disconnect mine when I got that soound and still passed smog check. There a cover on top of that pump you can yake it off and let someone start the car while you stand in front of the passenger headlight you can hear it come from the air pump, that how I found out. Also check on the the stikies on aux airpump. Hope this help.

 

[mercedesbenz911]

This version looks a little different. Seems you have the later version and you may have to remove the viscous fan clutch then swivel the tensioning pulley to get that belt off.
http://www.w124-zone.com/downloads/MB CD/W124/w124CD1/Program/Engine/104/13-1200.pdf

I guess it is possible to get a wrench on it without removing the fan if you have the right one. Anyway you have to make it swivel by turning it clockwise to remove tension from belt.

That looks like the one, thanks!

 

[Clarkz71]

When you get the belt off, start it and if the noise is gone then spend time
checking all the accesories and pullys.

 

[mercedesbenz911]

Good news! After figuring out the belt tensioner IS in fact spring loaded it was a breeze. The alternator bearings were kaput.

At first I nearly shat a brick thinking that I overfilled the oil when I performed an oil change the same day and ruined the engine. Whew, what a relief.

Dealer retail for new alternator: $860 + tax. Nope.

Bosch rebuilt alternator from Advanced Auto: $250 + $100 core charge + special order item. Nope.

Bosch rebuilt alternator online: $182 + $100 core charge, and waiting time for shipping, and the pain of shipping the old unit back. Nope.

Local shop that installed 2 new bearings for $35 in 30 minutes. Yep.

 

[Rupununipete]

You have to love that.

 

[sbaert]

...Local shop that installed 2 new bearings for $35 in 30 minutes. Yep...

Glad you found your problem for very little money.

Only 1 question though, what brand bearing did they install on the alternator?

If it's not a reputable piece like from INA or SKF, you'll be revisiting this in the very near future.

 

[mercedesbenz911]

I have no idea to be honest. But all they do all day long is rebuild alternators and starters. It's held up so far.