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Discussion Starter #1
Good evening,

2013 r172 SLK55 AMG, 28000 miles.

Fun toy, dropped the top for the first time today (along with swinging the tach north of 4000 RPM for the first time), however the exhaust note was boring and the thrust was very strong, but I was expecting more on both counts.

One flashlight, one screwdriver, and 2 minutes later I determined that the actuator on the right side of the exhaust tries its best to sync up with the left, unfortunately it appears to have suffered physical damage such that the shaft is not connected to the stepper motor. It freely opens and closes under the slightest touch while the actuator whines and fusses ineffectually.

The left side doesn't move at all during with the Smartkey in position 1, nor do I hear any sounds, my assumption is that it is fine, just waiting for the crippled right side to sync up. Probably a bad assumption, but it is my starting point.

Short version; left side flap makes no sound and doesn't move during the start/test portion. right side can be opened and closed by hand with no resistance, independently of the machinations of the actuator. it is obviously no longer connected to the actuator, but the shaft shows no indication of wobble, so I am hoping it is a connecting piece/cotter pin deal that I can easily repair.

I do not have a lift to get a good look at the mechanism, so if someone could point me to an exploded diagram of the actuator, tips on getting it out or repair, etc. it would be greatly appreciated!

The common problems I found on the internet search I did were about totally dead units, not a disconnect between the shaft and the flap.



thanks and so forth!

-D
 

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Registered 2013 SLK 55 AMG
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Hi Drex,


Both valves sound like they're broken. When the ignition is switched on, you should hear both exhaust valves cycle open and closed, before resting in the closed position. The ECU does this to confirm operation and that they are in sync and if they are not you will hear them continue to try to move. Faults are logged but I don't believe will light the EML, but interrogation will show the issue exists. Replace both and things will improve.


The bark from high revs (above say 4000rpm) and large throttle is pretty good, although a removal of the post-resonator secondary silencer/CATs will bring some more edge to the note we're told. I may plan to do this as my next mod sometime.
 

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Super Moderator UK SLK 55 AMG 2007
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@Drex
If you post your VIN we can look up the part fitted to your car.
Normally that gives us an exploded view that we can post and might be what you are after.


I'm going out but @jbanks15 @WoZ53 and @dbgrn might be around to help.
 

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Discussion Starter #4
Thanks!

The part is 1909064500 Left/right. Shoved the cellphone up around it and got a really terrible picture, but it appears to be held on by two or three studs and nuts. The case looks like I might be able to split it, determine and possibly repair the internal failure. (will get new ones, just like to tinker with the old) Unless it is a lot harder than a grainy cellphone picture seems to indicate, probably 30 minutes of my labor and the parts on each side, including a beer before bolting the new ones in. Car is, of course, about 2 months out of warranty.

My assumption is that it is a simple worm gear from motor to flat gear, with current limit threshold in the magic computer machine, so the position can be calibrated via the corresponding voltage or logic after they sweep from stop to stop in the tailpipe and then can be controlled with a reasonable degree of accuracy after that. If so, and if case splitting/reassembly are possible, a repair should be doable, with the bonus that I would likely be able to play with adding internal stops to keep the flaps slight cracked open all the time and the computer would simply adjust for it in the sync/calibration stage and never know the difference. Essentially pre-clocking to my choice of opening angle and having it think it was totally closed, would still further open the valve in the appropriate stages. Not sure I would chose to do so, but a man does get bored sometimes...


-D
 
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