2009/S211 E220cdi - Idle Noise - Should I be worried?

[Mintyfresh77]

A few months ago I occasionally noticed a very faint chirping noise from the front of the engine while at idle, initially it was only noticeable when I had the bonnet up and was stood listening to the engine carefully. Fast forward to now and the noise is there almost all of the time now at idle but in fairness does improve at fast idle, I removed the belt thinking it would be a pulley/bearing or something of that nature and ran the engine but to my horror the noise persists which sent a chill down my spine. I spent some time listening to various areas at the front of the engine and worryingly the sound which can be heard in the video is coming from the area where I am guessing the camshaft/sprocket chain is located. The noise is more of a faint chirp and not a rattle of any kind and it's loudest when my ear is close to the the engine number sticker seen in the video.

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I have sunk quite a bit of money into this car over the last 18 months basically bringing it back up to a good standard both in the engine and suspension but this worries me as it's coming from where the serious hardware is located. If I has just purchased the car I would not be that concerned and assume it was a characteristic of the engine sound BUT it didn't used to do this.

Really would appreciate some hypothesis on what this is most likely to be either by the techs that are on here or the experiences of others because I can't find anything relating to OM646 issues of this nature on the forums and I was under the belief that this engine was one of the more durable units in this dept. Car has done 133k, had full Benz history up until about 100k. Had oil change only 4000 miles ago using Mobil 1 5w 30.

 

[DSM10000]

Are you sure it's not an idler, belt tensioner or pulley?

You could take the serpentine belt off and run the engine briefly and see if the noise goes away and if so then check the idlers etc for noise by spinning them by hand (engine off!)

 

[Mintyfresh77]

Are you sure it's not an idler, belt tensioner or pulley?

You could take the serpentine belt off and run the engine briefly and see if the noise goes away and if so then check the idlers etc for noise by spinning them by hand (engine off!)

Hey DSM, Already done that. Belt, tensioner and pulleys changed last year too. This is what worries me. The fact it still made that noise when the belt was off has spooked me and putting my ear up to the area that label is on zero's it right in that location. Can you hear the noise I'm talking about? It's not in your face loud but it's there and it's running in perfect time with the engine

 

[SteveFromAvantgarde]

Sounds like the Alternator clutch pulley to me. Usually the culprit on the 646. If you remove the belt and spin the alternator it should spin quite freely and if you grab it hard you should feel it freewheel in your hand. If it doesn't and the alternator stops dead in your hand, then its seized.

Also check the water pump, they can make a chirping noise when the bearing is on the way to collapsing.

Either way, both fairly cheap components and repairs.

 

[DSM10000]

Hey DSM, Already done that. Belt, tensioner and pulleys changed last year too. This is what worries me. The fact it still made that noise when the belt was off has spooked me and putting my ear up to the area that label is on zero's it right in that location. Can you hear the noise I'm talking about? It's not in your face loud but it's there and it's running in perfect time with the engine

I can hear it. It does sound like a bearing noise though.

 

[Mintyfresh77]

Sounds like the Alternator clutch pulley to me. Usually the culprit on the 646. If you remove the belt and spin the alternator it should spin quite freely and if you grab it hard you should feel it freewheel in your hand. If it doesn't and the alternator stops dead in your hand, then its seized.

Also check the water pump, they can make a chirping noise when the bearing is on the way to collapsing.

Either way, both fairly cheap components and repairs.

Hi, Thanks for the input. Altenator clutch pulley replaced within last 6 months and noise is still there when water pump pulley is stationary (aux belt removed) so pretty sure its none of the belt driven ancillaries.

 

[Mintyfresh77]

I can hear it. It does sound like a bearing noise though.

That's what worries me. I'm not sure what a duff camshaft bearing sounds like, or worn tensioner/guide or lifters or even if those kind of faults are even applicable to my situation but something in the top front section of that engine isn't happy.

 

[Mintyfresh77]

**Update**

So I took the car to an Indy and initially based off of the video I sent them they were hoping it would be something like blow by on one of the injectors but alas it wasn't to be. The High pressure fuel pump is the culprit.

The quote for getting the 'new' part (very few in UK) and would most likely have to come from mainland Europe was £950 + Fitting etc comes to a grand total of £1385. To be fair I know HPFP's are expensive so I didn't cry on the phone.

I have sourced a recon unit from PF Jones for £420 and I will get £120 back when I send the old unit in to them so £300 in total. I use PF Jones for anything fuel system related on cars, they have both brand new and recon and offer excellent service.

Does anybody have any experience fitting these. I get that the removal and refitting is relatively straight forward but is there any little tips or procedures to be followed? I will leave thr car over night to allow fuel system pressure to dissipate to safe levels.

Do they have seals that need to be replaced on the mating surfaces? What is the torque of the bolts supposed to be upon refitting?

Any wisdom is appreciated

Thanks

Chris

 

[boxer 01]

**Update**

So I took the car to an Indy and initially based off of the video I sent them they were hoping it would be something like blow by on one of the injectors but alas it wasn't to be. The High pressure fuel pump is the culprit.

The quote for getting the 'new' part (very few in UK) and would most likely have to come from mainland Europe was £950 + Fitting etc comes to a grand total of £1385. To be fair I know HPFP's are expensive so I didn't cry on the phone.

I have sourced a recon unit from PF Jones for £420 and I will get £120 back when I send the old unit in to them so £300 in total. I use PF Jones for anything fuel system related on cars, they have both brand new and recon and offer excellent service.

Does anybody have any experience fitting these. I get that the removal and refitting is relatively straight forward but is there any little tips or procedures to be followed? I will leave thr car over night to allow fuel system pressure to dissipate to safe levels.

Do they have seals that need to be replaced on the mating surfaces? What is the torque of the bolts supposed to be upon refitting?

Any wisdom is appreciated

Thanks

Chris

I had my hp fuel pump reconditioned by pf jones a couple of months ago and the pumps been fine, they did try to charge me a lot more than initially quoted but we came to a mutual settlement.
I don't really know where the pump is located on your engine as mines the om642 and pump is located on the front of engine and was was easy to remove, three bolts and it was off, and an o ring seal which I got from MB. I struggled with one of the electrical connecters as the little tab that supposed to slide upwards snapped off. I would also get new hose clips for the rubber fuel hoses.

 

[Mintyfresh77]

I had my hp fuel pump reconditioned by pf jones a couple of months ago and the pumps been fine, they did try to charge me a lot more than initially quoted but we came to a mutual settlement.
I don't really know where the pump is located on your engine as mines the om642 and pump is located on the front of engine and was was easy to remove, three bolts and it was off, and an o ring seal which I got from MB. I struggled with one of the electrical connecters as the little tab that supposed to slide upwards snapped off. I would also get new hose clips for the rubber fuel hoses.

Hi boxer01 and thanks for the reply. Pump is located at the front of my engine the same as yours and I think it's roughly the same 3 bolt setup. Thanks for your thoughts on parts. I'll pop down to Mercedes and talk to parts dept ref any o rings required and a good point from you too on new hose clips. I know the kind of connectors you are talking about, they are royal pain in the rear. Thanks again