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New member so please pardon any posting faux pas. I have a 2011 E350 4MATIC with 80K miles. Since the past year, at startup, there is a chirping noise that has been coming from the engine compartment - please see attached video. The noise happens at startup and goes away when the car has been driven/warmed up a bit (it seems). I have had a few independents had a look but they have not been able to diagnose. The serpentine belt is new and the tensioner, I am told is also OK. Next step would be the dealer but want to see if this forum can help. Don't want give the AD a blank check to diagnose the issue - that will not be good for my wallet.
What about the idler pulley? Normally, it's tensioner, belt and pulley that gets replaced. The way the belt marking appears at every chirp says it's one of those pulleys.
You should replace both pulleys, they both tend to go bad after a while. Mine went bad with as little as 60k. I think it's either INA or Gates which is OEM. INA I think, but Gates is also good. Brand probably doesn't matter that much, I also used Continental too. As others said, normally you just replace all of it, tensioner, pulleys and belt at the same time. While you're at it, you should do the thermostat too, those tend to go also and it's right there with the pulley. Wahler is OEM on the thermostat. Another tip would be to check the oil separator/breather cover while you're there, intake manifold going is pretty common the M272.
Can you do us a favor, please. This is for database.
I am speaking based on M276, but probably your M272 is very similar. I am totally not familiar with M272.
When you replace the 2 of guide pulley, can you observe the side of the pulley inner side ( towards engine ) does it have the dots like below on the pulley I marked R :
Please take note, which pulley location has its dots on the inner side.
For mine, brand new pulley so happened to be :
Pulley on top of water pump #6 has its dots on the outer side ( facing the bolt or radiator) and the pulley above the tensioner #7 has its dots facing engine block.
Pulley #7
Pulley #6
Secondly, when you remove the pulley, how is the bolt and its plastic bushing tightness towards pulley bore ? Can it fall off when held up side down, or is very tight ?
My old one is very loose and new one is very tight as such I do not even want to mess with the pre-inserted bolt.
My wear and tear of the pulley, is not from its bearing, but the worn out plastic bushing. As seen here : https://mbworld.org/forums/e-class-w...ml#post8636632
I do not have the chirp you got, but I can see belt movement is not super stable smooth for its "tracking".
See below :
M276 no washer at the rear/engine side of the pulley, only at the front to push and make contact with bearing inner race.
Yes, two of them. No M276 here. At least when something goes on one car I know what to look out for on the other. Waiting for the oil cooler gaskets to go on the other M272 engine.
S-Prihadi, my friend, I wish I was as handy with the mechanicals of the car as yourself. I will have to have a repair shop take care of this issue for me. I do, though appreciate you posting such a detailed response to my question. Will post how the issue gets resolved. Dropping the car off for repairs this coming Thursday.
S-Prihadi, my friend, I wish I was as handy with the mechanicals of the car as yourself. I will have to have a repair shop take care of this issue for me. I do, though appreciate you posting such a detailed response to my question. Will post how the issue gets resolved. Dropping the car off for repairs this coming Thursday.
Hi, just wanted to close out on this thread. The belt, tensioner and idler pulley were replaced and the noise has been gone. Thanks everyone for your help.
10-09-2022, 11:19 PM
