I have a problem with my tranny, and it's been running this way for about 15K miles. No one can figure it out and i get contradicting diagnosis. I got two diagnosis that it's bad clutch packs. Then i got a diagnosis that says its not the clutch packs becuase the "adaptations" are within range. I guess that means it shifting right.

Anyways, the problem is that under light load, without changing gear, i get non harmonic vibration from the drivetrain. It sounds more like from the rear to driveshaft to tranny, but sometimes vice versa. Tranny shift through all the gears fine (at right points).

Negative glycol test and i get no codes. Changed valve body and Tranny control module. 125Kmiles. 03 e500

Start with tries, then drive shaft, then axles, then brakes.

If you really think it is the trans (which apparently you do as you've only worked on that) then change the trans mount next before going on to the other.

From your description, assuming that it's transmission related, the first two things I would check would be the transmission mount, and another glycol test.

Mercedes transmission mounts are pretty easy to diagnose. There seems to be a sweet spot around 3000 rpm's where the transmission mount jumps around and lets you know it's bad. With the car in park, rev the engine up to 3000 rpm's and hold it there. If there is a lot of noise and or vibration from the middle of the transmission tunnel area, your trans mount has likely given up.

The reason for another glycol test would be to definitely rule it out. I have run around and around in circles chasing a vibration/droning from what sounded like the rear axle/differential area that turned out to be a glycol contamination issue. I have also seen tests that passed the first time but later on failed as the contamination progressed. Was the test performed by a dealership? If not I would recommend seeing a dealership because it is a pretty sensitive test.

Hope this was helpful.

It's not your clutch packs. When these start to go bad, it's a snowball effect. The transmission would be slipping. It wouldn't last 500 miles before it totally died. I would be more inclined to believe it's a bad mount.

I agree,, that is what I have experienced on auto tranny's.

I had vibration in mine and had the engine and transmission mounts replaced under warranty. Smooth as a new car now. 88,000 miles.

The same mechanic (indy) said the mount was ok and pointed to the clutch packs (second time). I'll try to rev it like you said and see if it vibrates.

The glycol test was done at the dealership. They are the ones who told me to change the valve body. Another dealership said since glycol was negative and since we changed the valve body, then it's the clutch packs (first time). A different indy (merc mechanic) said STAR shows the adaptations are within range and try the TCM. Spent over $2k (parts & oil only - all labor done myself) and no fix.

Thanks VERY much guys. Cant get more frustrating than something being broken and no one knowing what's wrong. AND it's NOT getting worse! LOL

Not to split hairs here. But are you getting a vibration or chatter? I remember back in the 90's Ford had a problem with their tranny fluid and it would cause the lockup in the torque converter to chatter in third and fourth gear. Have you flushed the transmission fluid? If you had bad clutch packs you could tell for sure by doing a pressure check on the transmission. Like I said earlier, if you were loosing pressure there, it would have destroyed itself by this time. Maybe your solenoid for the lockup converter is bad. the converter is supposed to lock up under slight loads. You can try driving the car with a scanner on it and watch the torque converter lockup solenoid command. See if the chatter happens while it is activated. If it does, it's either a bad solenoid or torque converter.

It's definitely a vibration and not a chatter. It's exactly what OLDSCHOOLRICE describes as vibrating/droning noise from the rear and tranny area. Would the bad solenoid throw a code/light? Your theory sounds very logical. The when the dealership test drove the car with me, the technician put the car in drive, held down the brake, and pressed the accelerator. He then said it's not the converter - guess it wasn't vibrating.

OLDSCHOOLRICE
I did the tranny mount test and it did vibrate a little bit - but not at 3000 RPM. It DID however slightly vibrate as it would have vibrated if i was driving it (from 1500-2700 RPM). I will buy a tranny mount and put it on over the weekend and see if it fixes it. As for glycol, although it was done by the dealership, i'll get a second sample and get it blackstone labs to check again. I do have the Valeo radiator (and 3 weeks ago got a one time "check coolant level" that never came back). It's a May 2002 production date . Dealerships were pretty convinced that it was NOT glycol because of the high mileage - should have went a long time ago. And do you think if i did have glycol that i would be able to drive it for 15K miles longer? And if it is contaminated, would a dealership help me with getting the tranny replaced - since this is a well known design flaw?

Thanks again.

The when the dealership test drove the car with me, the technician put the car in drive, held down the brake, and pressed the accelerator. He then said it's not the converter - guess it wasn't vibrating.

If he did this while the car was stopped. He's not checking the "lock up" function of the torque converter. The converter doesn't "lock up" while the car isn't moving. When it "locks up" it's basically direct drive(like letting out the clutch on a manual transmission). I don't think it locks up until 3rd gear. You have to drive the car with a scanner and watch the solenoid command. If the converter wasn't locking up at all, I'm sure it would trigger a cel, due to the engine rpm vs. vehicle speed.

You did say it's a vibration, this is just something to consider if it you can't isolate the problem.

I'd say that it wouldn't hurt to try a trans mount. Due to the fact that you say the vibration is happening while the vehicle is in park I would say that it's highly unlikely to be anything inside the transmission or in the drivetrain(driveshaft, differential, axles, etc...).

As far as the dealership helping you with the repair due to glycol contaminaion, if it's a decent dealership they should be willing to give you some sort of discount. Not due to the fact that it's a common issue, but more so because you went to them and spent some money for diagnosis.

Good luck and let us know what happens with the trans mount.

Can anyone tell/show me where the tranny mount is? I ordered one and i should be getting it today, so i can work on it this weekend.

Replaced the tranny mount today... but it wasn't bad at all. It looked brand new.

So i took some tranny oil out from the pan and ill send it over to blackstone labs. the end is near...

Test came back... NO Glycol... High amounts of iron though. Oil was good.

I also realized something. When i drive "slower" - like in no traffic, just cruising straight at speed limit, it doesn't do it as bad - even when i push it up a hill a bit. I've also noticed that when i disconnect the battery, the same happens, until i drive the work the next morning in traffic. Could this be an issue with cooling?

My last hope is a tranny flush. I've changed the fluid twice already by just dropping the pan. Does anyone think it's worth getting the flush since i've already changed the fluid & filter twice? Does the oil in the torque converter get filtered out too during the operation?

Thanks for all the help guys.