Transmission shifting HARD

**matt09** · 12-18-2006, 08:48 PM

My car, a 96 C280, got the ATF changed at 80,000 miles 2 weeks ago. After changing the oil (with MB's tranny fluid), I noticed the car was shifting rough so the fluid was drained again and replaced with another 8 quarts and that seemed to fix the problem.
However, a couple of days ago something weird happened:
I was driving at around 45 mph and tried to overtake someone. I pushed the pedal half way through, and the transmission downshifted to 3rd gear which seemed stranged to me as it normally takes more gas to make it do that. After doing that, I stopped before a red light and when it turned green and I tried to accelerate, the revs went up to 4000 rpms quickly even though I was slightly pressing the gas pedal and the car moved very slowly (worn clutch effect?). I immediately went to an MB shop I normally go to, and when they test drove the car it wasnt doing that anymore, instead it was shifting extremely rough. They adjusted a valve that regulates the oil pressure on the transmission and that seemed to fix the problem, until I drove it the next day.....
Now, the car works flawlessly while its cold (And lasts like that for around 10 mins), but when it fully warms up the transmission shifts in a very aggressive way from 2nd to 3rd (Like someone hitting my car from behind), and moderately hard from 3rd to 4th.
I was just wondering if anyone has gone through this and found what causes this horrible shifting.

BTW, I went through all the transmission threads that popped up with the search button and I couldn't find definite answers.

**RemoLexi** · 12-18-2006, 09:31 PM

only thing that comes to my mind - tranny mounts and would a flex-disc do that ??

**matt09** · 12-18-2006, 09:36 PM

Originally posted by RemoLexi
only thing that comes to my mind - tranny mounts and would a flex-disc do that ??

Flex disk has been replaced. Tranny mounts? Mmm the car doesnt shift rough from 1st to 2nd gear :ermm: . I'll have that checked though, thanks. I hope I get plenty of replies

.

**jnenad16** · 12-18-2006, 10:50 PM

Im just hoping they didnt put in the wrong fluid. did they replace the filter during the fluid change? rough shifting usually comes from a failing modulator or leaking vacuum line. you say the trans felt like it was slipping, that the revs went up high, but the trans didnt shift in time. that sounds like low line pressure instance. that could be a sign of a bad front pump.
there could be several different things causing this. either way, take the car to a shop that specializes in benzes and that has a good reputation, and have them give it a thorough inspection.

nenad

**OzC36** · 12-19-2006, 02:06 AM

This might help?

http://www.continentalimports.com/ser_ic20242.html

**Polestar** · 12-19-2006, 06:30 AM

Nice link, OzC36!

**matt09** · 12-19-2006, 07:24 AM

Originally posted by jnenad16
Im just hoping they didnt put in the wrong fluid. did they replace the filter during the fluid change? rough shifting usually comes from a failing modulator or leaking vacuum line. you say the trans felt like it was slipping, that the revs went up high, but the trans didnt shift in time. that sounds like low line pressure instance. that could be a sign of a bad front pump.
there could be several different things causing this. either way, take the car to a shop that specializes in benzes and that has a good reputation, and have them give it a thorough inspection.

nenad

He didnt use the wrong fluid, the guy worked for Mercedes for more than 20 years and decided to start his own shop.
The worn out clutch effect only happened once, and after it it started shifting rough.
He's setting up an appointment with a friend of his that specializes in MB transmissions to give my car a spin a diagnose the problem. I'm just wondering if anyone had gone through this and found the source of it.

I'll post what was causing it after I meet with the MB transmissions dude.

**matt09** · 01-07-2007, 01:30 PM

UPDATE!

The MAN in MB transmissions met with me yesterday and inspected my transmission. After taking off a bunch of stuff from underneath the transmission (oil pan, filter, heatsink-like stuff....) and looking for anything wrong we noticed that there was a bit of water in there! You can tell because the oil in the rear part of it looked milky-pinkish.
The MB mechanic has gone through that before and is mainly caused due to a faulty radiator, but since the amount of water is so small he ruled that out.
I have no idea how water got in there since I supervised the tranny oil change I paid for a couple of weeks ago, and the car didnt shift rough before I had the oil changed... (Unless one of the Dexron quarts had water in it... Mmmm I'LL SUE THEM!!! Lol, jk)

I tried searching this forum for a similar incident but no luck. Has anyone gone through this?
Oh BTW, the solution is to drop and clean everything and do an oil change followed by another one in a short period of time.

**Polestar** · 01-07-2007, 01:40 PM

Has anyone gone through this?

Nope!

So, how is it shifting now?

**matt09** · 01-07-2007, 01:48 PM

Originally posted by Polestar
Nope!

So, how is it shifting now?

Wont be able to try it out until monday. As he was taking everything off there was a really thin black seal:

And since the transmission had never been touched before it was very hard to peel it off and broke. It was a saturday and the MB dealer didnt have the part in stock so I have to wait until monday for the part to arrive ($10 dollars only).

**jnenad16** · 01-07-2007, 07:19 PM

and why did you remove the valve body?

nenad

**matt09** · 01-07-2007, 08:27 PM

Originally posted by jnenad16
and why did you remove the valve body?

nenad

They believed the reason for the hard shifting was due to an obstruction there I think.

**matt09** · 01-08-2007, 04:06 PM

YAY! I got my car back today, and the transmission feels like if it was new!!!!
The MB tech cleaned everything by hand, refilled the tranny with 7 quarts of Dexron III and the car shifts PERFECTLY.
I am FREAKING happy right now....
Since the guy that owns the shop is my friend, they charged me 50 dollars for parts (Tranny filter + 7 quarts of oil [At $2 a quart!!!] + The seal that broke + Oil Cap [It had one from a turbodiesel for some reason] AND $50 for labor!!!!!

**Denlasoul** · 01-10-2007, 11:14 AM

Keep us updated in a few months to see if the problems reoccur.

Thanks!

**xvvvz** · 01-10-2007, 12:14 PM

>>Dexron III <<

Is MB fluid really just Dextron III with a new label on the bottle? That would save a lot of money compared to MB's prices.

**matt09** · 01-10-2007, 12:48 PM

Mmmm I tiped in Dexron III into google to see if the bottles looked familiar but none of them did. I'll take a closer look at them because it was definitely Dexron III but had a another name after that. The guy that owns the shop worked at an MB dealer for 20 something years and he confirmed that that was the transmission oil they used at the dealer.

**Espresso** · 01-10-2007, 01:08 PM

Multifunctional DEXRON III-Generation

**kameraguy** · 01-11-2007, 05:43 AM

Excellent! Glad you didn't have to go through more costly inspection and good thing the problem seems to be minor.

If only we all had a "hook-up" to a MB tech who knew their way around a MB!

btw- did your tranny produce any trouble codes? if so, can you post them here? It may be of help in case someone searches for them.

**matt09** · 01-11-2007, 08:49 AM

No trouble codes. I only had a check engine light because of unplugged-broken vacuum lines.

**allirroz** · 01-12-2007, 05:45 AM

Originally posted by xvvvz
>>Dexron III <<

Is MB fluid really just Dextron III with a new label on the bottle? That would save a lot of money compared to MB's prices.

I have a MB booklet that indicates transmission's 722.3/4 use DEX III and the 722.6 uses the MB bottled trans fluids. Is there a
difference? Your guess is as good as mine.

I think the 96 c280's does have the 722.3 trans in which case Dex 3 would be the proper fluid.

**MBHustla858** · 01-18-2007, 10:18 PM

that unplugged vacuum line was for the transmission,
if your car is a 96 it doesn't have a ELECTRONIC Transmission, all they did was connect that vacuum line and sell you a tranny service.

dexron 3 is what is used in those older trans, all the newer benzos have to use the factory synthetic.

**matt09** · 01-21-2007, 05:45 PM

Originally posted by MBHustla858
that unplugged vacuum line was for the transmission,
if your car is a 96 it doesn't have a ELECTRONIC Transmission, all they did was connect that vacuum line and sell you a tranny service.

dexron 3 is what is used in those older trans, all the newer benzos have to use the factory synthetic.

Huh? The unplugged-broken lines were from the EGR valve to the front of the engine. I witnessed the whole work, saw the water inside the valve body and he also changed the vacuum lines, scanned the car 3 times, cleared the codes and replaced a broken dash bulb for free.
BTW, the car still runs like a champ.

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