Transmission fluid change
 

My car is need of a transmission fluid/filter change according to the serivce guides...but have had no problems regarding the transmission what-so-ever.

There is shop that I go to that can change the entire fluid fluid and refill with the same amount without changing the filter.

Basically it attaches on one end...sucks the entire fluid out and replaces it with the same amount.

Should I do this or drain the fluid, change the filter, and refill?

-Ren

What this shop is referring to is often times called "power flushing". Many places that offers such serves require that you first sign a waiver releasing them from responsibility.

Why?

Because this approach has a tendency to loosen dirty that may be in the system. A spec smaller than you can imagine can deep-six your tranny.

There's a defined approach to changing MB tranny fluid and filter. In most cases it involves draining the converter, main pan; replacing the filter. Hire an garage versed in MB repairs/services.

If you want good service from the transmission, the pan needs to be dropped and the filter changed. We're not talking about a complicated mechanical process here. Six bolts for the pan, and three screws for the filter. While the pan is off, a good mechanic will thoroughly clean out any accumulated residue from the bottom of the pan. Most often that will be very fine metal shavings.

For the do-it-yourselfer, it is important to note that the transmission pan gasket that Mercedes uses is a soft rubber gasket - easily split if you tighten down the pan bolts too much. So, use a torque wrench and the right torque values.

Ken300D

thanks for the heads up guys

there is probably a reason why the designers and engineers write the service manuals huh ;-)

Not changing ANY FILTER when recommended, to me, is like washing your face with a dirty wash rag. There just are no shortcuts worth taking with these lesser expensive maintanance items. I had an 86 300SDL tranny act up with erratic shifting patterns only to find out that the MB dealer I bought it from at 80,000 K had not changed the trans. fluid and filter and had indicated on the service record that he had. I had it properly done in Minneapolis which resulted in a full quart of the severely contaminated fluid ending up on the selling MB dealership manager's desk and the service manager trying to explain. You had to been there to see how pathetic this was. It cured the shifting problem and drove it another 40,000K without any further problems.

I recently changed my AT filter and fluid, dead easy.

Like indicated in the posts, six bolts, three screws, new pan gasket, and some ATF.

I have typed up the full instructions for someone last night, I will be more than happy to send them to you if you like.

hey Pilot...do send me ur list

rmv3396@hotmail.com

as for the fluid itself....i can get from the dealer right?

(don't shoot me....if no one posts....i will do a search) :-)

Ren

Unless you have one of those new-fangled permanent fill 5-speed ATs, you should be fine with commonly available Dexron III/Mercon or one of the synthetic alternatives. Your manual will say for sure.

Sixto
91 300SE
81 300SD

Not to start yet another "synthetic vs. regular" debate, you may want to consider using Mobil 1 synthetic ATF. I switched over since my car sits out in the cold while I'm at work, and like synthetic motor oil it doesn't thicken up as much as conventional ATF in the cold. Also runs a bit cooler (they say) in the summer due to decreased friction.

Also, don't forget to drain the torque converter! That's the only tricky part.

Pilot,
Can you send me instructions as well, or better yet post them here? Did you drain the converter?

asrosen1@excite.com

Pilot,
I too would like to have a copy of your instructions as I am going to attempt this feat in the coming weeks...

bsmith@i2k.com

I understand that it is not brainsurgery, more like removing a splinter, but I get a little nervous when "possibly killing the transmission" has been referenced more than once... :eek:

Thanks!

How about a "Synthetic vs. Synthetic" debate? (Just kidding)
 

I always use Reline or Amsoil synthetic in long service items like the transmission or axle. Renfy, by all means change the filter at suggested intervals, empty the pan and refill with new fluid in between if you want to, but do change the filter at the correct intervals.
Mobil has been changing their formula little by little hoping that you don't notice. Mobil 1 and Castrol Syntec are not true synthetics, they are ultra refined mineral oils (hydrocraking). I don't want to get in to it, but if you want more information search the Forum on hydrocracking and additives for the whole story.

I think the reason why people like the "power flushing" method of changing transmission fluid, is that the machine guarantees to change every drop of fluid.

In most transmissions, more than half of the fluid remains in the torque converter, and is not drained when the fluid is changed by dropping the pan or pulling the drain plug.

Mercedes is the only transmission that I'm aware of that allows fluid to be drained from the torque converter, which has its own drain plug.

Thus, the benefit of using the power flushing machines is really nullified.

When I was in my younger days, my Chrylser/Dodge products all had drain plugs in their torque convertors. I thought every car did.

Wait... Chrylser... Mercedes... Oh yea, It's the same company.:p

Drain trans hot or cold?
 

The engine oil and differential are to be changed hot and it is said in many discussions. No one ever says if the trans is to be changed hot as well. Any advice on this?

Steve