Hey guys, I normally wouldn't post this here, but it seems the most experienced and most technical M113 guys are in here. So I bow down to your collective wisdom to keep me from selling this car out of frustration.

Here are the details:

2005 S500 4matic
M113 NA/722.6
53,500 miles
mostly used for short commuting trips.

In the past, lets call it 8k miles I've done the following:

New:
Fuel filter
spark plugs
plug wires
one new coil pack
air filters
oil change
EGR valve/EGR switchover valve
MAP Sensor
MAF Sensor
Camshaft position sensor
intake gaskets
Tranny fluid and filter. (level is correct)
all vacuum lines
All intake tubing seals.
Motor mounts
Tranny mount
Harmonic dampner

In attempting to fix the problem I did:

Removed intake, cleaned internals, resealed
Cleaned Throttle Body
Had injectors ultrasonically cleaned...they were essentially perfect anyway

Here are pics of what it all looked like to show that the car is not carbon'ed up or otherwise in bad shape:









Now, let me describe the problem in more detail:

A mild vibration that can be felt through the brake pedal and body (floor and center console) at idle. Only while the car is in gear, not neutral or park. High frequency vibration, almost like a buzzing (should be about 28.75hz).
There is very little fluctuations in idle rpm, A/C has no impact.

For all practical purposes, the car runs absolutely great. good power, no stumbling, stalling, starting issues, etc, but this vibration drives me absolutely nuts. I KNOW it does not belong there and it not being right doesn't sit well with me.

This thing doesn't shake like a big block or anything. If you were used to most cars, you'd probably say its normal, but in an S-class, its not sposed to be there.

Now, you're probably reading this and saying, STOP THROWING PARTS AT IT AND START DIAGNOSING.

well, i answer, the car throws zero drivetrain codes. No engine, no tranny. Nothing. Its been to the dealer and several independents...they have NO answer for me whatsoever.

I bought a DAS setup and have been doing some of the steps explained by others for similar problems.

One is the smooth running and fault counter:



Fault counter was at zero for all holes.


Now I'd like to think I'm a fairly sophisticated DIY'er but I'm out of talent here.

I have a few direct questions:

1. How would I check the operation of the torque converter? Could it be unbalanced but still operate properly? Is it not balanced by the internal fluid flow?

2. Would anybody lend any credence to this:

https://mbworld.org/forums/c-class-w...ping-halt.html

I'm an open book on questions, fire away.

I need your help guys, I like this car so much but I'm at my wits end.

A heartfelt thank you!

 

Did you use OEM style Bosch plug wires?

 

i will put my money on the torque converter that is causing the vibration. i have the same issue on my rover.

 

Did you remove the serpentine belt and idle the car a few seconds to see if the vibration goes away?

 

Yes, OEM bosch from amazon

thats been a definite consideration. As a bigger expense though, I'm wondering if there is any way to test that. perhaps through DAS?

Yes, no change. Spun all accessories. waterpump makes a bit of noise but no wobble and like I said, no change in idle with that removed.

Thanks very much guys.

 

I should add that i've tried adding some idle rpm to overcome any potential excessive driveline load, and that didn't help.

idle in neutral and park is normal.

 

vibration only present when the car is in motion?? If this is the case, id put the car on a hoist and check the drive shaft carrier bearing, front to back for any dents that could throw off balance.

 

no sir, the vibration is at idle only and only at rest or less than 2mph (i.e. crawling)

 

Could it potentially be a fuel pump or injector issue?

 

The following might send you in the right direction. You'll need a second person and a hoist.

Lift the car on the hoist, remove all underpanelling. Put it in drive and see if the problem is still there. If it is,try to reproduce the vibration so it is constant, or, have someone else do it while you are underneath. Try to locate where the resonance is coming from. With a large prybar, try shifting the exhaust system, all mounts etc to see if the vibration changes.

Loosen engine mounts and lower the car on the ground. Let it idle, see if it changes the vibration. Do the same with the transmission mount.

Loosen the transmission mount brace and try repositioning it.

Loosen the mounting point of the exhaust to the transmission. Inspect the rubber isolator.


Hopefully that helps.

 

torque converter 90-95%

 

Fuel pressure is fine, so I don't believe so.

Injectors were flow tested and cleaned. After cleaning they each flowed bang on exactly the same with no leakage and a perfect spray pattern. No issues with impedence or anything else really.

I have to think the engine itself runs ok.

Those are good recommendations. I didn't even consider the thought of an exhaust hanger/mount.

Will look into this. Thanks

can you share what makes you think that and possibly a way to test it?

thanks

 

One thing i'd like to add:

On or about August 15, 2013, I had a torn boot on my passenger side front axle. I had a non MB specialist but respected indy swap the boot. The boot was on the inside CV and so instead of removing the cv from the differential, they simply pulled the stub shaft out of the CV, removed boot, repacked and reassembled.

I made my first thread about the vibration on 8/28/13.

Could this be related?

 

i ordered an exhaust hanger bracket rubber pad, but I doubt that will make any difference. At $4.50, who cares.

Anybody have any ideas on how to test or isolate the torque converter?

 

Using the access hole (black plastic triangle piece) , unbolt the torque converter from the flywheel and push it back (away) Then you can idle the engine without it.

I've seen bad or repacked CV shafts cause vibrations with 4matics, but only when moving.

 

Its funny, thats what i was thinking re torque converter, but I figured the car's computers would have an absolutely aneurysm if I did this.

thanks

 

Did you check the crank pulley? The 500 m113 motors had the crank pulley recalled years back I remember reading about vibrations due to bad crank pulleys.

 

I have replaced it. no issues that i can see with the new one.

 

My buddy had a strange vibration coming from his car, turned out to be the cat. Me and his sat in it at idle listening and hypothesizing for an hour. Mechanic put it on a lift and had it narrowed down to the dumb cat within minutes.

Anyway, I hope you find a solution for your car bud.

Best regards

 

We had a e class 4 matic that had the same problems a few years back that after the axle boots were done had a vibration at or just off idle in gear while stationary. It did turn out to be the axles. I do not have a good explanation for how it does it but we found a internal tech case that referenced this and we replaced the axles. Unfortunately the axles were updated and the front spindles had to be replaced as well. Very expensive but it did fix it.
I would try what was suggested above 1st for the free up all the exhaust mounts and engine mounts and transmission mount and make sure nothing is loaded or bound. I lift the engine up and down with a jack with the bolts a little loose and then tighten everything back up. If this does not do it I think that the axle may be your problem.

 

is the vibration constant or does it last 5 seconds and then go away?
Pop the hood and and then start the car, if its felt through the brake pedal it leads me to think the ABS is vibrating like in the E55's. Could also be the torque converter if its more constant vibration.
With the hood open and car idling in park, having just been started up, watch the SBC unit to see if it shakes.

everything else i suspect has been checked or commented on above.

 

thats interesting and is similar to something i heard.

It does not go away after 5 seconds. w220s do not have SBC, just a regular vacuum booster. vacuum is normal.

thanks guys.

 

Try Loosening the exhaust at the manifold to pipe flange on both sides, cat to resonator as well as the hangers and re tightnen. Sometimes the exhaust has pressure on it and it can cause a vibration.

I also have seen the front cv's cause a vibration at idle in gear on w203's but not a w220. Not sure why it does it but there is a internal MB document about it and I've seen it happen first hand.

 

You say it does not vibrate in park or neutral so it cannot be the torque converter. Vibrating in drive then definitely a transmission issue.

 

Got your PM. It can be the torque converter when placed under load. (Drive) Any high pitched whines on startup from the TC area? Any noise from TC when revving in Neutral or Park? I can give you a typical sound clip if needed. They really howl when failure is imminent & then take out the tranny oil pump.

From everything you have stated this is a mechanical issue or noise & not related to tuning & electronics. It might be a harmonic or primary mechanical noise. The fact that it only occurs when you load the engine is telling.

It could be anything from something touching e.g. exhaust heat shield, to a rear tranny mount, to a TC, to a piece of Cat monolith that has broken off, to a loose tail shaft flange nut on the transmission, the EECS circuit & purge valve or sympathetic vibration that needs to be moved out of the audible spectrum. The joys of NVH engineering.

I suggest you buy a $5 mechanic's stethescope, place the car on a hoist with brakes on & in Drive & tie down exactly where the noise is emanating from.



Good Luck