Is this normal? - PeachParts Mercedes-Benz Forum

gmercoleza · #1 12-15-2004, 12:47 PM

91 300E, 126,000 miles. I believe my trans starts out in 2nd gear (correct me if I'm wrong). Anyways, if it starts in 2nd gear, then when the trans shifts from 3rd to 4th (the 2nd shift) I think it may be slightly "sloppy." Now when I say sloppy, I mean it doesn't shift as crisply or firmly as the shift from 2nd to 3rd. 2nd to 3rd is very tight and sometimes even seems to slam (although I have learned from all my other previous Mercedes that this is a fairly common trait). But the shift from 3rd to 4th isn't as quick, in fact it seems to last a split second longer, perhaps more closely resembling the shift quality of an American car. It sort of feels like you're driving a manual transmission and letting the clutch out a little more slowly than usual. There's a definite beginning and end to the shift process, but it just seems to last slightly longer than I'm used to, almost as if it's "hanging" for just a moment before actually shifting. And under load (i.e. spirited acceleration) the hanging seems more pronounced. But if you drive the car moderately (i.e. normal acceleration and not like you stole it) you almost don't notice it.

I have owned the car since beginning of August and have put 8,000 miles on it without any problems. Either the slow shifting just started recently, or I never noticed it before. I have checked the fluid twice since I bought it, most recently about a month ago. The fluid looked almost new and was at the proper level. Should I change the fluid and filter just to be safe? Should I run a trans flush first? If so, can anyone recommend a specific product?

Is this normal? Am I just paranoid?

Thanks in advance everyone!

Jackd · #2 12-15-2004, 01:09 PM

1) Check the transmission fluid level and make sure it is right.
2) When was the last time the transmission oil/filter has been replaced. Sometime, new oil makes miracles.
3) You can adjust the transmission firmness/sloppiness with the vacuum activated transmission modulator. A very easy task.
it is located on the left side of the transmission. There is a plastic cover (about 2 1/2in diameter).remove carefully. Turn the adjustment counterclockwise for firmer shifts, clockwise for sloppier shifts. Only a few degrees at the time.

nglitz · #3 12-15-2004, 11:14 PM

Quote:

Originally Posted by gmercoleza

91 300E, 126,000 miles. I believe my trans starts out in 2nd gear (correct me if I'm wrong).

You are correct. It will start in first if you "floor it". There's a microswitch that does the job. Or if, while stopped, you pull the shift lever back to "2" and than back up to drive, it will start in first that one time. Great fun.

gmercoleza · #4 12-17-2004, 11:38 AM

Thanks for the input, however I wasn't looking for instructions on how to change the fluid or adjust the modulator. What I wanted to know is if this type of shifting is normal. Is the somewhat sloppy shift an indicator of impending transmission failure? Or is it maybe just something "sticking" which might be cured by running a trans cleaner through there and then flushing/changing the fluid?

Again, it runs and shifts pretty normally except for the slightly softer and longer (i.e. not as "crisp") shift from 3rd to 4th.

#5 12-17-2004, 12:14 PM

it's not politically correct to label anything "normal."

dtf · #6 12-17-2004, 12:22 PM

You're talking about that almost 'clutch feeling' shift? My wagon has done that since the day I bought it with 66,000 miles. It increases the harder you step on the gas right? Sounds 'normal'. Mine actually does it more on the 1 to 2nd gear shift when I jump on it.

Jackd · #7 12-17-2004, 12:38 PM

Sloppiness is not normal, this is why I suggested you could need a modulator adjustment.
On part throttle, the 3 to 4th gear shift should almost be imperceptible but should not feel as "hanging' between gears.
You said: "And under load (i.e. spirited acceleration) the hanging seems more pronounced". Again, this is not normal. A stronger acceleration should produce a crisper shift, not a longer "hanging".
At least, this is how mine operates

gmercoleza · #8 12-17-2004, 12:45 PM

Quote:

Originally Posted by dtf

You're talking about that almost 'clutch feeling' shift? My wagon has done that since the day I bought it with 66,000 miles. It increases the harder you step on the gas right? Sounds 'normal'. Mine actually does it more on the 1 to 2nd gear shift when I jump on it.

YES - you hit the nail on the head! That's exactly what mine feels like, and I started worrying that maybe something is slipping and that the trans is on its way out. And yes, it increases the harder you step on it, meaning it seems to take longer to shift. But under moderate or light throttle, you don't even notice it.

How many miles are on your wagon now? And does it still do the clutch shift? If so, have you noticed it worsening at all over the years? How often do you change the fluid & filter? And most importantly, for purposes of comparison, what type of wagon are we talking about - 123 or 124? Mine is a 124 (300E) with 126,000 miles.

Thanks for the input!

gmercoleza · #9 12-17-2004, 12:48 PM

Quote:

Originally Posted by Jackd

Sloppiness is not normal, this is why I suggested you could need a modulator adjustment.
On part throttle, the 3 to 4th gear shift should almost be imperceptible but should not feel as "hanging' between gears.
You said: "And under load (i.e. spirited acceleration) the hanging seems more pronounced". Again, this is not normal. A stronger acceleration should produce a crisper shift, not a longer "hanging".
At least, this is how mine operates

Thanks again for the input. I agree; the sloppiness just doesn't seem normal. If I were to adjust the modulator to tighten up the sloppy shift, wouldn't that make all the other shifts even tighter than they already are? Then wouldn't they slam into gear?

It would seem that if all the other gears shift tightly and just this one shift is sloppy, then perhaps something inside the transmission hanging or sticking is the culprit and should be corrected. Do you think running something like Trans-X through there and then flushing/refilling would be a good idea?

Just thinking out loud...

gmercoleza · #10 01-07-2005, 11:38 AM

Bump to the top - the problem has taken a turn for the worse. Now the trans slips from 3rd to 4th - I had to drive home in 3rd the whole way yesterday. The first shift is tight, no problems. Reverse also works fine. The car is now parked in my garage and I took my wife's Odyssey to work. There's no way I'm driving it if there's any chance of doing further damage.

Due to the research I have done here (lots of info!), I'm leaning away from adjustment or modulation, and leaning more towards friction parts or stuck check balls or pistons. I plan to open the trans tonight and see if there are shavings in the pan (hopefully not). I have done a search but still don't fully understand if this could be related to B1 or not - the symptoms don't seem to be the same. Can anyone chime in? If replacing B1 would solve the problem, that would be great - way cheaper than having to replace the trans!

If there is nothing in the pan, I am going to try and flush/refill the fluid and change the filter. But I also figure that if I'm in there, I should remove and either clean the valve body or replace with a new one. It seems that the valve body is easy to remove in one piece without dropping the trans, but can be very difficult to take apart properly, without losing little parts (correct me if I'm wrong). But I'm very careful and meticulous; I've done many carburetors in the past and, though I'm sure the valve body is a million times more complex and is an entirely different beast, it's nothing that time, patience, and skill can't tackle. I'm hoping this is just a case of gunk sticking up some of the check balls or something like that. But again, I am somewhat shooting in the dark here - can anyone tell me if doing this is worthwhile? Are there any other partial-rebuild steps that I can perform with the trans still in the car, other than valve body and B1?

Supposing I decide to just change the fluid and filter, will I need to purchase any additional gaskets or seals, such as for the transmission oil pan? And should I use synthetic or dino trans fluid? And how many quarts should I pick up? I'm already familiar with the process for draining the torque converter...

HELP!!! Anyone???

Bruno_300TE · #11 01-07-2005, 11:55 AM

Yes, replace filter and gasket. It will be between 6 and 7 quarts (6.2?), I plan to use synthetic for my next change. Lubegard is supposed to be a good additive (the red bottle). Make sure not to overtighten the pan (torque is 8nM if I recall correctly).
Bruno

gmercoleza · #12 01-07-2005, 11:57 AM

Quote:

Originally Posted by Bruno_300TE

Yes, replace filter and gasket. It will be between 6 and 7 quarts (6.2?), I plan to use synthetic for my next change. Lubegard is supposed to be a good additive (the red bottle). Make sure not to overtighten the pan (torque is 8nM if I recall correctly).
Bruno

Thanks Bruno. Will I also need to buy a gasket for the pan? Or is the existing gasket reusable?

Bruno_300TE · #13 01-07-2005, 12:06 PM

Use a new gasket - I bought filter and gasket as a kit for 19$.
Good luck, Bruno

gmercoleza · #14 01-07-2005, 12:17 PM

Can anyone else chime in regarding the possible benefits or side effects of cleaning or replacing the valve body? Also, what other partial-rebuild repairs can be performed without removing the trans? Does this sound like a B1 issue?

haasman · #15 01-07-2005, 12:26 PM

gmercoleza
Follow the good advice here: Change the ATF fluid completely (trans drain and torque converter) and the filter and gasket. Use MBZ parts!

Adjust you vacuum modulator. Check for vacuum leaks.

I have been using synthetic ATF (Mobil 1) in all the cars and it works great.

If the trans has been properly serviced you shouldn't have to touch the valve body at all.

Keep us posted,

Haasman