fly2nite

I cross-posted this on AMG PL but this forum gets so much traffic, I thought I'd check here too.

My 2007 E63 has approximately 50,000 miles on it now and has had all maintenance performed, including the transmission service a few thousand miles ago. I drive the car as it was intended, and enjoy strong starts in S mode and first gear. I usually leave traction control engaged, and often see the light flicker as it keeps me under control. Recently my car has started making what I can only describe as a grinding, low end harmonic or growling noise when in first gear doing a hard launch. It does it regardless of whether I have traction turned on or off, and even does it in dyno mode, so it's not electronic nanny interference. I've never heard or felt this noise before, and it only happens in a strong pull from first gear, and is intermittent during the pull, but does not continue into 2nd gear or beyond. It also doesn't change pitch with the rpm of the engine, and doesn't usually manifest until i'm well into the powerband.

I checked the flex discs on the driveshaft and the one up front is visibly spidered, but not torn and appears to be in ok shape just a little old. To my ear, it seems the noise is coming from the left side of the vehicle, and anywhere from the engine back to the rear wheels. It's almost like the noise you hear during a track day and hard cornering, when the car is braking automatically to keep you from spinning, but I wouldn't think these systems would be activated in dyno mode.

Strangely, it doesn't seem to impair my power delivery at all. I first noticed it while doing a 1/4 mile run, and actually achieved my best time when it occurred. No CELs or warnings of any kind have appeared.

I've searched multiple forums and cannot find anyone having experienced this issue. Anyone have any thoughts? I tried to record the sound, but it's about 75% sensory through the floor and pedals, and is such a low frequency noise, it gets drowned out by the thunder of 507 clydesdales.

Anyone have any thoughts? I hate the thought of taking it to a dealership and telling them to wring it out until they experience it, that's pretty much my worst nightmare of dealerships anyway.

NCE500

Sounds like you need motor mounts? My driver side mount broke last year, and the alternator was apparently making contact with the sway bar at WOT with a resulting resonance heard inside. Another symptom was that the driver side air intake tube kept popping off at the air cleaner. New (supposedly improved) mounts cured everything. Be sure to have the tranny mount replaced at the same time.

If it's something else, please let us know what you find. Good luck with it.

fly2nite

Interesting, I hadn't read of that in my searches. I just looked at the area around the alternator and can't find evidence that it's been contacting the sway bar, but going back out to check the intake tube. this sounds very much like what i'm hearing though, some kind of engine noise being made louder by contact with something, but it doesnt change pitch as rpms rise so i'm not sure. Interestingly, just typing this I recall that earlier today that when facing the engine, the pax side of the removable engine cover had been popped up along with that intake tube..

Just took a short video of the engine revving mildly in drive, then reverse, then park to show movement. Uploading now..

fly2nite

Here's the vid. Does this look like an acceptable amount of movement? I started out in Drive, then a few in reverse, then harder in Drive, then a few in Park. Edit - might need to go full screen to see the movement.

CLKCLK

I think I have the same problem. I got it after headers, 82mm throttle upgrade and TCU tune. All mounts and trans mount were replaced. At first, I thought my rear main seal leak caused the slippage, but nothing changed after the rear main seal fixed. I still could not figure it out.

theblckghst

check the fasteners on the heat shield along the header/exhaust areas...could be that one has backed out a little bit and is making contact with one of the aformentioned parts.

fly2nite

Interesting you mentioned the heat shields as I was under there today and one was contacting the cat, but I fixed it and the noise remained. Sounds almost like a wheel is slipping inside the tire, its pretty unnerving. Heading to dealership tomorrow. Maybe it's a belt but I think it'd slip in all gears not just first. Definitely sounds as if it's coming from drivers side of engine bay all the way back to read wheels. Hard to pinpoint.

fly2nite

Here's an audio clip, I guess it is audible after all. Did four runs here. If you turn up the bass you can hear the low end noise through first gear, but disappears in 2nd. The first three runs i had the mic in the floorboard of the driver side, the last run i put it in the passenger side.

http://k005.kiwi6.com/hotlink/x5y4p38tvr/memo2.mp3

fly2nite

I did some more looking around and I think you're right, it's the mounts. Another person on AMG PL said they experienced the same issue and their exhaust was touching the frame at WOT. I looked and found the driver side exhaust to be resting about 1/2 inch from the frame, and i can see the engine moving that much during revving, so I'm sure this is it. I squeezed under the car and took photos of both mounts and some orangy sauce that had dried against the frame under and around the mounts.. Sounds like you nailed it. Dropping off at Park Place Dallas tomorrow, they said they keep mounts in stock and should have it back within a day .

Some pics from under the mount, it's hard to get a camera in there.. This is drivers side but both sides had dried fluid. Hard to believe the vibrations just now manifested, I can't wait to feel it with the new mounts:

This one shows the orange sauce (i guess it's hydraulic fluid)


You can see the grey plastic engine mount shroud with dried fluid.


Left side exhaust clearance (shown here) is much higher than right side:


Here's the right side clearance.

theblckghst

just watched the video, its not the mounts. I listened to the sound clip and I cant hear anything. You might want to consider the trans mounts also. I had the same problem, replaced my mounts, and although they were broken, the problem actually was worse after replacement. It took weeks of tooling around to find one fastener almost as far back as the resonator that had backed out and was resting on the pipe. It wasnt visible either, found it by hand on accident. Best bet, get under your car when its cool and put your hands all over your pipes from front to back and try to feel for the problem.

fly2nite

Picked up the car from the dealership this afternoon after getting all three mounts replaced. This absolutely solved my problem, and after looking at the exhaust clearance compared to the pics above, the difference is night and day. Before, there was about a half inch clearance on driver side and now there's a good 1.5 inches. Idles smoothly and no more noise under heavy acceleration.

A word about the repair process...Props to NAC aftermarket warranty for not giving any grief about replacing all three. They did argue for a much lower shop rate with my dealer, claiming someone down the road would do it for $90/hr. In what is a first for me, Park Place met them in the middle and didn't charge me the difference. Props to Jay Moore, my SA for eating the difference and he wouldn't have even told me had I not asked.

Thanks for the insight, fellas!

NCE500

Glad you got it sorted out.

+1 for NAC. They covered a front airmatic shock on my 63 last month and several costly items on my little C55 last week without drama. Very happy with them so far.