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Transmission losing smoothness

13K views 25 replies 12 participants last post by  Paul Monk 
#1 ·
my 2003 SLK230 is now up to 85k miles and beginning to shift a little less smoothly (automatic trans) than when purchased at 48k miles. No maintenance is mentioned in owners manual, manual says take to dealer even to check oil level. Any suggestions?
 
#4 ·
That depends on your mechanical skills. Its Fairley simple to change, you will need a set of torx sockets to remove the pan bolts. When I changed my oil/filter I also placed a strong round magnet in the corner of the pan to catch any metal partials just in case.


ps: you will also need a dip stick, MB calls it a tool. Best and cheapest place to get one is Ebay for around $25 + shipping.
 
#7 ·
The friction material on the plates or clutches is disintegrating. This is due to either abuse or the transmission fluid and filter haven't been changed periodically.

Get the fluid and filter changed pronto! Any transmission shop can do it. The only caution is to use a fluid with the same coefficient of friction as the clutches. Probably best to get the MB fluid.:tazz:
 
#8 ·
Connected problems?



I perhaps have a similar problem in that, particularly at low temps & starting out, the 1-2/2-3 shift will sort of clunk into place, and when slowing down, it feels like the transmission doesn't want to disengage until it's right at the point of stopping. (So I get this clunk/de-surge at that point.)

I've mentioned this to my dealer several times but they've offered no solution. (No real a surprise there.) I bought the car with 50k (and the problems) and now have 110k. Switching back and forth between S & W modes doesn't seem to effect the problems/performance.

Mostly this is annoying more than anything.

In maybe a related problem/issue, particularly if I'm just rolling down a long steeper grade under cruise; 1) the car will shift down to maintain speed (which is quite abrupt!) and it is seemingly going back and forth into a mode where it is utilizing engine braking. (So it feels as if the system is retarding then releasing, retarding then releasing, 10-20 times per mile.) Perhaps this is the way it's supposed to work - though neither of my Fords did anything like this - so I might have two issues.

First, the low speed shifting in the transmission, which sounds like a similar issue to the initial poster's and which the suggestions above might help, and second, the transmission/cruise/engine speed interaction, which might or might not be related or helped.

Anyone with any similar issues?
 
#9 ·
I perhaps have a similar problem in that, particularly at low temps & starting out, the 1-2/2-3 shift will sort of clunk into place, and when slowing down, it feels like the transmission doesn't want to disengage until it's right at the point of stopping. (So I get this clunk/de-surge at that point.)

I've mentioned this to my dealer several times but they've offered no solution. (No real a surprise there.) I bought the car with 50k (and the problems) and now have 110k. Switching back and forth between S & W modes doesn't seem to effect the problems/performance.

Mostly this is annoying more than anything.

In maybe a related problem/issue, particularly if I'm just rolling down a long steeper grade under cruise; 1) the car will shift down to maintain speed (which is quite abrupt!) and it is seemingly going back and forth into a mode where it is utilizing engine braking. (So it feels as if the system is retarding then releasing, retarding then releasing, 10-20 times per mile.) Perhaps this is the way it's supposed to work - though neither of my Fords did anything like this - so I might have two issues.

First, the low speed shifting in the transmission, which sounds like a similar issue to the initial poster's and which the suggestions above might help, and second, the transmission/cruise/engine speed interaction, which might or might not be related or helped.

Anyone with any similar issues?
EXACTLY the same problem that I have. More annoying than anything and of course I am worried it is doing damage. Not yet found a solution, might try getting the fluid changed.
 
#11 ·
Okay, so now I've bought fluid, filter, gasket, drain plug washer and a "key" for the dipstick cover from an MB dealer ($217). Also got a set of Torx sockets for the pan. A few more questions before starting though:

1. How to know when the amount of added new fluid is correct - the parts guy said "we put in 5 quarts". Is it necessary to buy a dipstick and check fluid level, or just assume 5 qts is ok?
2. The dipstick cover doesn't seem to come off after inserting the red plastic key - should the cover be forced even if it has to be broken?
3. I'm assuming the new fluid has to be injected through the dipstick tube - is this right?

About the post re clunking on startup - my SLK230 has similar symptom, starting up at around 1/4 throttle there's a light clunk from 1 to 2 and 2 - 3 gear, particularly if throttle position happens to be changed at the the same time as the shift is taking place. Sometimes light clunk also occurs when down shifting through lower gears. Hopefully the new fluid and filter will smooth things out.
 
#15 ·
1) Get a dip stick don't guess on the amount.
2) The red key needs to be removed before the cap comes off.
3) That is correct, dipstick tube. Get a funnel with a long neck.

In my past experience when i lost a trans there was no warning, it just stopped working. Maybe others had a different experience.
 
#12 ·
Automatic transmissions are subjected to a lot of stress and wear over time. Much of it can be reduced by periodic maintenance and a gentle driving style, but getting close to or over a 100K means getting it removed and overhauled.

The MB 7-speed unit is a complicated unit with it mechanicals plus some computer software involvement. Expect to spend several thousand dollars for a complete overhaul. It would be wise to find a shop that specializes in MB (and other high-buck rides) for a repair. It doesn't necessarily mean a dealer either. Many Benz dealers just remove the unit and send it out to a independent contractor. You may save some money eliminating the dealer.
 
#14 ·
If there is one service that owners shouldn't tackle, it the automatic transmission no matter what speed it is.

It is obvious that the fellow above with the parts doesn't know what he is doing. I recommend he take his parts to a qualified shop and have the service done.

It is a lot more than just changing the fluid, filter and gaskets. There are inspections that need to made to determine what condition the unit is in. For example, does the oil have any contaminants from deteriorating friction materials? There are adjustments to be done to the shift program either mechanical or software. Also it is a PITA to lay on your back rather than take a comfortable look at things beneath a lift.

In my area, the Benz dealer charges $250 for labor plus parts. That's a deal when you consider that the work is guaranteed. :soap:
 
#19 ·
Not what Ive been told.....

I have changed the converter on my 99 C230 kompressor 140 kmi., it made a difference. I now have a 99 SLK230 107kmi., bought with a bad motor due to a small hole in the oil pan. While doing an engine swap I also did the converter due to ease of changing at the time. My converter rebuilder who I have used for about 20 years told me that the Benz 5 spd. converter has alot going on inside it compared to most others. Specifically stated something about "clutches" not just fins going on inside them, and that these converters do wear down.
 
#20 ·
. . . While doing an engine swap I also did the converter due to ease of changing at the time. . . . .
In some near future I'm going to have to replace the rear crank seal, so, like yours, it would be a good time to consider it.

A few G-Whiz questions then . . . . So did you get a rebuilt unit, new one, or have yours rebuilt? Guesstimate on the cost for the TC method you chose? Did you feel any noticable improvements? (Though if you were swapping that much, the whole car might have felt different.)

:Beer:
 
#26 ·
My R170 (fitted with the standard 722.6 automatic transmission) was very harsh in its gear changes. I fully drained all of the old transmission fluid, changed the filter and refilled the trans with Mercedes approved fully synthetic transmission fluid. The difference was immediate and very surprising! The transmission was transformed and felt like new. It was a very satisfying experience.

Sent from my F3115 using Tapatalk
 
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