We have a 2011 E350 that my wife primarily drives and it makes this squeaking noise from the front of the engine around the belt and or other pulleys. The thing is ... it only does this on first startup in the morning after it has been sitting all night in the garage and after the engine has been running for a few minutes it seems to go away. In January 2024 the Mercedes dealer changed the V-Ribbed Belt and the Belt Tensioner. The car had 59,000 miles. I thought the problem was corrected but now with 62,000 miles it is still doing the same. With the hood closed my wife probably did not pay attention that the issue had come back or was there all the time and did not realize it. I have an appointment to bring it back to the dealer next week as they are backed up in the service department. While waiting I just wanted to see if anyone else has encountered this problem. I made a video in the morning while this was happening and you can view it at the link below.


Thanks

So take it back to the dealer. They are the ones who replaced the parts.

The chirping sound when at 50th second ( lower RPM ), its only 3Hz or 3 times per second.
I would think belt would be faster than that, if the sound is from a pulley.

BTW, aside from serpentine tensioner, did 2 of the guide pulleys get replaced too ?


This is the 3hz I speak of :



Your video is a 29FPS. So 1 second it has 29 frames. Above is I cut exact 1 second, 50th second frame 1 to frame 29.
The one in cyan blue is the audio, only 3 chirps.


Maybe your PCV is the one making the noise, like below video : Below is M276, yours is M272, but it would be similar PCV system


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M156. The chirps is as slow as yours.

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Yes, that is the plan as I mentioned in the opening post. They are backed up and it will be a few days before I can get it to them. While waiting just wanted to see if anyone else had experienced this problem.

Thanks for the reply ... The 2 guide pulleys were not replaced.

+1 on the pulleys as noted by @S-Prihadi imo.

This is definitely pulley noise, not belt, the upper one with grooves and the one below that, smooth one, might as well change both, they are not expensive parts.
Pretty typical on these engines.

The belt, tensioner and 2 upper idler pulleys have been replaced and it still makes the squeaking noise at startup after sitting overnight. It seems to go away after engine been running for a minute or two. I am beginning to think it is the bearing in another item like the water pump but don't know how to check that. Also, all my pulleys have grooves there are no smooth ones. See attached video.

To check the water pump pulley you have to remove the belt and check for play on the pulley. Grab the water pump pulley with your hand and gently try and see if there is vertical or lateral movement...a good pulley will have no movement. If there is any play on the pulley it is time to replace the water pump.

Get a empty paper towel tube, hold one end to your ear and start the car, this will help you locate the squeal, be it the alternator, air pump or water pump

Thanks, I will give that a try.

Thanks, I will give that a try.

Let this baby issue serves as incentive to find an honest shop that can take 5mn to fix issues as expected.

There is nothing more basic than this for a specialist doing a belt job... it's hard not to fix it when you're paying top dollar for the best MB experts.

Tensioner + belt+ idlers replaced then this!

These crickets sounds like a pulley misalignment or one of the loose accessories is wobbling.

Belt needs to come off, free play inspected. An MB expert will know which pulley is built to walk off its shaft (steering pp?).
Normally that 5mn is included in the repair without taking a 2nd mortgage.

Sorry a basic job got messed up into this. Trust that this happens to the best of us.
You know there's more maintenance coming your way, find true specialists to serve your needs.

Tranny + differential oils are ASAP!

[QUOTE=CaliBenzDriver;9043471]Let this baby issue serves as incentive to find an honest shop that can take 5mn to fix issues as expected.

There is nothing more basic than this for a specialist doing a belt job... it's hard not to fix it when you're paying top dollar for the best MB experts.

Tensioner + belt+ idlers replaced then this!

These crickets sounds like a pulley misalignment or one of the loose accessories is wobbling.

Belt needs to come off, free play inspected. An MB expert will know which pulley is built to walk off its shaft (steering pp?).
Normally that 5mn is included in the repair without taking a 2nd mortgage.

Sorry a basic job got messed up into this. Trust that this happens to the best of us.
You know there's more maintenance coming your way, find true specialists to serve your needs.

Tranny + differential oils are

The car has always been serviced at the dealer where we purchased it from here in Houston. This is a strange problem though in that it is only audible after vehicle has been sitting overnight and last for a minute or two. The dealer charged $1,400 to replace just the belt and tensioner and the issue came back. They wanted another $1,000 to replace the two idler pulleys. I found a more reasonable repair shop that changed them for $200. Issue is still there and has me concerned because my wife drives this car. Mainly concerned something could freeze up and break the belt while highway driving. I will get it back to the shop next week so they can investigate further.

A tire-shop would to do a better job...

The dry idlers are the first parts to go bad then the belt and the bad tensioner.

Having a Mercedes dealer charge $2400 to replace $100 entry level parts in reverse order... is why you did the right thing to find a knowledgeable shop.

Give them your maintenance jobs to keep your car on the road without costly failures.

​​​​​​Ask your shop for tranny + diff oil service.

Next review records for ignition sparkplugs and coils while you're at it (TX has high heat that age coils prematurely).

Timely maintenance will save you bundles in unnecessary repairs.

Well, I tried a little test since the problem is only noticable on first startup after the car has been sitting overnight. This makes it extremely hard for a tech to diagnose as it only last for a minute or two and quiet down. So the previous evening I sprayed a little belt dressing to the belt and let the vehicle sit overnight. This morning when I cranked it up there was no chirping or squeaking from the belt. However, now I do get the squeaking continuously when I rev the engine rpm's between 1,500 and 2,000. At least now a tech can duplicate the issue long enough to find where the noise is coming from.

Now your belt is extra noisy after belt dressing.

The super long serpentine transfers power to all the accessories.

Pointers... :

• one of your accessory is seizing up
• belt/tensioner mismatched (FCPe did that to me!)
• misaligned pulley

Your excellent indy shop will have you fixed in no time. Until then keep an eye on the water temp gauge, pump is a belt accessory.

I got the problem resolved by taking the vehicle to a independent Mercedes shop. They were able to duplicate the issue after vehicle sat overnight in their shop. Tech removed the belt and examined all external components and pulleys. Then it was discovered that when the Mercedes dealership replaced the belt back in January 2024 they did not use the correct OEM part it seemed to be an aftermarket belt. He got the correct OEM part, installed it on the vehicle and after testing even letting the vehicle sit overnight the problem with the squeaking is resolved.

Shame on the Mercedes-Benz dealership here in Houston for doing that considering they charged me $1,500 to change the belt and belt tensioner. Just the labor included in the $1,500 total was $900. On top of that they wanted another $1,000 to change two additional pulleys when we first brought the car back to them to check their original work instead of checking the belt which would have resolved the issue. So much for having your car serviced at the dealership!!!

You're welcome

Glad everything worked out exactly as planned.
🤗

THANKS

That's nuts and so disappointing, if not criminal. But I have seen this behavior before. Loyal customer takes their OLD car in for repairs. The dealership is under pressure to sell new cars. (Dealerships get ranked on the number of new cars they sell. High ranking dealers get cars with all of the popular options. Lower ranking dealers get the hard-to-sell cars.) Charge the customer an outrageous amount for a simple repair (how do they document that since there are fixed labor hours in the ASRA?). If they come back, charge another insulting amount. Next comes the pitch that maybe a NEW SHINY MERCEDES is in their future.

I got my first Mercedes, a 2004 SL500 with 50k miles back in 2017 from a coworker. She had taken her car in for a B Service and $3500 later they gave her a list of recommended repairs and services totaling $10,000. She was sick of paying for a car that looked like it was dying. They offered her $10k as a trade-in on a shiny new GLE. Knowing I was a car guy, she told me the story. I offered her $10k on the spot, promising to take excellent care of her "baby". Later, I was able to do all the recommended stuff for a little over $1000 in parts (water pump, spark plugs, lower control arms, trunk struts, etc.). Some of the stuff was not even needed to be replaced, like the water pump.

I would definitely go back to the dealer with this info and ask for your money back, that they charged you for Genuine parts and used inferior aftermarket parts, which is clearly fraud. Tell them that you are happy to "share your experience" on Facebook, Yelp!, and one of the largest Mercedes internet forums.

What hourly rate do they charge to come up with $900 labor? What belt and tensioner costs $600? Your receipt should show an itemized list of part numbers and procedure codes. Check FCP Euro for parts prices and someone should be able to look up the hours allotment for the labor in ASRA.

The squeaky belt was probably due to an ever so slight misalignment. When cold, it slipped enough to make the noise. Friction heated it up and it soften a bit and gripped better. The belt dressing masked the problem temporarily until it wore off.

hey uh, theres like a washer on one of the idlers, can you shop me a top town view of it running just to make sure all the pulleys are aligned? it's easy to mess this up. I see it all the time. Also do me a favor and check your power steering reservoir, if it's leaking onto the belt itll slip on startup