I found a few threads on possible exhaust leaks, but most terminate with a joke or being chocked up to valve train noise.

Here's my issue: Finally was able to take the car out after months of wet streets and snow. The streets were clean and dry after large amounts of rain (to wash the salt away). Any way, after flogging it for a while to clean out some carbon , I did my usual inspection. The typically noisy valve train is still there, but so is a louder, more imposing tick. I opened the hood and all sounds normal (for this engine). Valves and injectors tapping away, but under the car on the passenger side, there is a distinct tick that is in time with engine RPM. It is definitely on the driver's side and is not distinguishable from the engine compartment, but is very noticeable when listening from under the car, near the engine. It sounds kind of tinny or metalic, but I've heard exhaust leaks that sound similar depending on the thickness of the piping. I can't pinpoint the exact location however. So, I'm hoping it isn't a lifter banging or other engine component. Could this possibly be an exhaust leak at the header collector flange? Is this a normal sound for this German sewing machine, or...? The car has about 13k on the clock. To my knowledge, it's never been bottomed out on anything. I've spent a ton of time under the car inspecting things. No scrapes or similar markings. I've had it checked out by the service department, but of course, everything sounds normal to us, bla, bla, bla.

Thanks for any suggestions or advice!

 

My SRT makes the same noise, it sounds like a flange gasket but I haven't checked it out yet though. It might just be engine noise that's more noticeable where the car is so low to the ground.

 

I have the exact same problem. My service advisor noticed the sound, and had the technician do the soapy water test on the entire exhaust. The problem persists, even though no exhaust leak was found. I'll keep you posted if I hear anything this week.

 

I wonder if it could be a leak around one of the 4 oxygen sensors.

 

Maybe it's nothing. Maybe we're just worried about our babies to much.

 

Mine does it too... Has since I bought it and hasn't gotten worse. I've just gotten used to the fact that these cars make odd noises that they really shouldn't. I find it strange that a Mercedes Engine lacks so much in refinement, but I guess even they through idle quality and noise out the window for performance.

 

Put some actual soundproofing on your hood underneath the hood insulator and it should sound much better.

 

I have dynamatted the entire car, and the sound is still there. It's no a sound deadening issue. This is much more.

 

Thanks for the replies guys!

I screwed up my description. It's on the DRIVER'S SIDE, not the passenger side like I previously stated. I was thinking about something else on the passenger side when I wrote this post. This sound is on the driver's side. Sorry 'bout that.

Man, seems like we always find the same issues with our cars and we end up all having the same or similar resolutions if any! Ha, it's funny because I've read and heard many auto journalists rave about this particular Mercedes engine, especially the hand-assembled version. They talk about how refined it is, how smooth it is, and how tough it is. I'll betcha if this was an American-built engine, they'd say it is noisy, makes unusual noises, and is a little un-refined! Well, it is smooth, powerful, and hopefully will last forever like many Merc engines do, but man, it seems like I hear a new, puzzling, annoying, and worrying sound every time I drive the darn thing. It groans, stumbles, and ticks, but goes like snot! Maybe it's just too quiet, maybe I'll just put a perf. muffler on it so I don't have to hear the squirrels knocking around in their cages anymore!!

On a serious note, I wonder if it's a pump, or some kind of solenoid that lives on that side of the car. Why would we all have the same sound on the same side of the car unless it is supposed to be there? Hmmm, some of the other noises could be due to the fact that there are 12 spark plugs firing off too. Could be coil noise, or arcing, or who knows what. German cars have always been known for quirks, and this one definitely has some. I'll just stop worrying about it and drive it until it dies either by old age, or by launching through the block. "Hey, why does your car tick and make all those noises?" "I don't know, I guess the pistons are starting their NASA organization!"

Really, if anyone finds a solution or a cause of this noise and others, let us know! The elec. tape on the hatch latch bar was brilliant!!

 

In my observations auto journalists will declare an engine unrefined if it is buzzy, noisy, harsh sounding, rough, etc. Our engines have unusual noises at idle but in no other way can they be considered unrefined. And once they are revved up, all idle noise is forgiven. I like to think of the idle noises as technology at work.

As for the hatch rattle, what hatch rattle? I don't hear a peep anymore. Lowly duct tape once again proves it's worth.

 

It's not duct tape, its 200mph tape! Once you can dig up a buck or two, get some nice, black electrical tape to replace that ugly 200mph tape, it will hold up better in the summer heat! Hmmm, maybe I'll try duct tape on my header flanges to cure the noises!! jk

 

To locate sounds and leaks I found that using a length of hose helps to act as a stethoscope. You can localize the noise much better this way.

If you go to harbor freight for 10$ you can get a mechanics stethoscope for hearing bearings, valves and internal sounds with very good precision. Waldig

 

Bringing this thread back from the dead . Had my car checked out, no exhaust leaks at all. Had a shop use a stethoscope, no abnormal noise of any sort. No coolant or oil leaks, my engine doesn't seem to be losing any oil over time at all which is a nice thing. I got used to high compression bumblebee Hondas consuming a good amount of it. What is the final verdict? Normal noise? Also could other with the same issue tell me if it happens under load or at neutral as well. Mine only does it under heavier load and the sound was not there when my IC pump was bad (got the car this way) and it's not supercharger related either. I can only hear the noise under load in lower RPM.. can't hear it in higher RPM either because it's not there or it gets drowned out by the road/engine/supercharger sound.

 

I have the same noise on my srt6 and it sounds like its coming from the driver as well. It is a exhuast ticking noise with moderate throttle only.

 

So you're saying that it is a normal exhaust noise? Do you think it is at the downpipe or the catback? I also thought it might be a cat going bad.

 

I don't think it is normal but rather common. I will have the car up in the air soon and try and take a look. My wife hates starting it and reving it while I'm underneath.