weird sound back left of engine bay e550 m278
05-31-2022, 10:33 AM
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C207 e550 2012
weird sound back left of engine bay e550 m278
Hi during idle, what is this sound? It’s from the back of the engine bay. It doesn’t always occur but turning off and on the car will remove the sound. 2012 141000 km m278 engine, e550 4.7L V8biturbo
https://drive.google.com/file/d/1rfsdbXWQVVf4V5ifpbu4dT21JETdZWZw/view?usp=drivesdk
https://drive.google.com/file/d/1rfsdbXWQVVf4V5ifpbu4dT21JETdZWZw/view?usp=drivesdk
Last edited by e550benzo; 05-31-2022 at 12:06 PM.
05-31-2022, 05:20 PM
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Can't really make it out, volume too low. Sure it's in the back there and not more fwd?
Or how about under the dash? I assume you'd know the difference but gotta ask.
When it does do it will it continue to do it or does it eventually time out?
Or how about under the dash? I assume you'd know the difference but gotta ask.
When it does do it will it continue to do it or does it eventually time out?
05-31-2022, 05:37 PM
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C207 e550 2012
A similar problem was posted in this thread however it wasn’t resolved. In this one the sound was faster
https://mbworld.org/forums/e-class-w...Hhg0&fs=e&s=cl
https://mbworld.org/forums/e-class-w...Hhg0&fs=e&s=cl
06-04-2022, 07:14 PM
#4
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I played it on a different computer and I hear it just fine now. It's nothing I recognize. That thingie in the back at the 6sec mark, with the rubber cover, is your fuel pump. Not sure if they make more noise when they start to fail but maybe someone can chime in. Also, I noticed in Xentry there was a setting/function to make it quieter. It's been a while and I didn't really care so I didn't retain much, but I would assume the pump is normally noisy enough to be annoying. Since there isn't much that can be done I'd say the fix was a rubber cover and setting to a lower psi at idle, both of which they did. On mine the normal psi is ~2450psi and quiet mode was something like 1700? I forget when it shifted to high pressure but it wasn't much past idle. So I suppose you could slowly rev it up to day 1000 and see if the sound suddenly get worse? Or maybe it's just stock on high pressure all the time?
I also don't know how, or if, fuel is recirculated back to the tank. I think it would but who knows, point being the return system could stop working and the pressure is now too high and making more noise as a result?
I don't know if you have a way to check any of that but the Autel AP200 is only ~$70 and can see the fuel pressures and tons of other useful things.
The sound in the other guys video is also nothing I recognize, but I did notice it seemed to be in sync with the belt. The loudest part seems to happen the same moment the white part on the belt appears. I can't imagine how anything would be in sync with the belt, excluding the belt itself, but check it out and maybe see if yours somehow matches it too? I can also see the crank pulley in the vid, kinda, but not enough time to see if it matches it. So I would consider marking your crank pulley with white tape and see if the sound syncs at all. The cams and fuel pump run at half crank speed, and the accessories should all be out of sync with it. Well, I assume out of sync unless their pulley is the same size as the cranks which seems unlikely, but you can see them so take a look.
I've also found accessory item issues by taking the belt off, but not so easy here. I have also pried the belt tensioner loose before, to stop the belt, but not something I'd suggest anyone else do unless you know both how and the risks.
I've also found them by hosing the belt and parts down. Either making the belt slip, which is unlikely here thanks to the tensioner, or the water dampens the noise directly. If for example an idler/tension pulley was the cause, a good douching from behind should quiet it. Just don't get the hose caught in there! I've had pulleys catch a variety of things and it's violent! Never a hose but it would rip the hose outta your hand, and possibly suck the whole frikkin hose in until it rips outta the wall. Something to think about, and the damage to the car or your personal body parts should they follow. A friend has half a thumb thanks to a similar situation. In my truck I used to throw a rag in a pulley just to show people because it looks so calm and low risk until you see it happen.
Not sure how many miles you have on your idler/tensioners but if they haven't replaced already then I'd imagine you're on borrowed time. It sucks when they go out on the road, and that is exactly when they do it. These engines already run too hot imo, and the moment one goes your temps shoot up fast so you should kill the eng as soon as it happens. From there you can't really drive it without risk. I've done it with cheapo cars, like drive a half mile, let it cool for 15, repeat. I wouldn't do it to this eng. So for most people you're lookin at a tow + down time at a shop that likely has to order the part, and lots-o-$. It's best to swap em out on your terms before that happens, plus you can ensure you got the better quality part that will last.
So if yours make any sound at all, or have any play in them, they're actively bobsledding to the grave.
Best of luck and please post when you figure it out so others can bennie from it.
I also don't know how, or if, fuel is recirculated back to the tank. I think it would but who knows, point being the return system could stop working and the pressure is now too high and making more noise as a result?
I don't know if you have a way to check any of that but the Autel AP200 is only ~$70 and can see the fuel pressures and tons of other useful things.
The sound in the other guys video is also nothing I recognize, but I did notice it seemed to be in sync with the belt. The loudest part seems to happen the same moment the white part on the belt appears. I can't imagine how anything would be in sync with the belt, excluding the belt itself, but check it out and maybe see if yours somehow matches it too? I can also see the crank pulley in the vid, kinda, but not enough time to see if it matches it. So I would consider marking your crank pulley with white tape and see if the sound syncs at all. The cams and fuel pump run at half crank speed, and the accessories should all be out of sync with it. Well, I assume out of sync unless their pulley is the same size as the cranks which seems unlikely, but you can see them so take a look.
I've also found accessory item issues by taking the belt off, but not so easy here. I have also pried the belt tensioner loose before, to stop the belt, but not something I'd suggest anyone else do unless you know both how and the risks.
I've also found them by hosing the belt and parts down. Either making the belt slip, which is unlikely here thanks to the tensioner, or the water dampens the noise directly. If for example an idler/tension pulley was the cause, a good douching from behind should quiet it. Just don't get the hose caught in there! I've had pulleys catch a variety of things and it's violent! Never a hose but it would rip the hose outta your hand, and possibly suck the whole frikkin hose in until it rips outta the wall. Something to think about, and the damage to the car or your personal body parts should they follow. A friend has half a thumb thanks to a similar situation. In my truck I used to throw a rag in a pulley just to show people because it looks so calm and low risk until you see it happen.
Not sure how many miles you have on your idler/tensioners but if they haven't replaced already then I'd imagine you're on borrowed time. It sucks when they go out on the road, and that is exactly when they do it. These engines already run too hot imo, and the moment one goes your temps shoot up fast so you should kill the eng as soon as it happens. From there you can't really drive it without risk. I've done it with cheapo cars, like drive a half mile, let it cool for 15, repeat. I wouldn't do it to this eng. So for most people you're lookin at a tow + down time at a shop that likely has to order the part, and lots-o-$. It's best to swap em out on your terms before that happens, plus you can ensure you got the better quality part that will last.
So if yours make any sound at all, or have any play in them, they're actively bobsledding to the grave.
Best of luck and please post when you figure it out so others can bennie from it.
06-28-2022, 04:39 PM
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2012 E550 Coupe
I have this same issue and it only happens every once in a while. The sound is coming from that wrapped cable looking thing on the top left of the engine. If you touch it you can feel the vibrations at the same rate as the noise, I have no idea what it is though. Haven't been able to find anything online either so will most likely take it to an indy shop and see what they say.
08-13-2022, 02:36 PM
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2013 W212 E350 RWD
I have this same issue and it only happens every once in a while. The sound is coming from that wrapped cable looking thing on the top left of the engine. If you touch it you can feel the vibrations at the same rate as the noise, I have no idea what it is though. Haven't been able to find anything online either so will most likely take it to an indy shop and see what they say.
The metallic cable is your fuel line if I think I understand what you're talking about. OP the back left of the M276 harbors the high pressure fuel pump that is mechanically actuated by a roller tappet. Have you experienced any fueling related issues, misfires, etc?
