wrote a quick "tranny fluid" service FAQ

[snik]

Hi,

to drain all tranny fluid, you need to drain the torque converter.

Start with the transmission pan drain bolt, it’s a 25 hex screw. This will drain about 2 liters of oil thats in there, now if you have not replaced your tranny filter, take off the pan, replace the filter and pan seal. If you want to skip this section that’s fine... you can access the torque converter bolt without removing the pan.

This picture shows the location of torque converter bolt with the pan removed (but its just as accessible with the pan in place)



Now that bolt doesnt just line up there (it spins with the torque converter), so look infront of the exhaust heat shield to where the arrow is pointing, and a picture of this area is posted below:



notice the 2 circles on either side? If you look through, you will see gears (torque converter gears).. what you do is put a screw driver and turn the torque converter one tooth at a time until that bolt lines up like the first pic.

Open the bolt, let it all drain (4~5 liters, put the screw back, check the pan screw to make sure its nice and tight, fil it up through the tranny dipstick to the first (cold) notch, drive the car until its at operating temperature (a 15-20 km highway run at 100 km/h will do the trick), then pull over and check the dipstick with the car in park, and engine running, fill if necessary, but do not exceed the 2nd (HOT) notch.

My fluid was nice and red after 20k, no burnt smell, and bottom of the pan was nice and clean. Car is a 93 S500 w/ 135k miles.

Good luck [:)]

[BENZDOC]

be sure to ONLY turn the engine clockwise (looking from front). very important....

[BENZDOC]

another tip is when the convertor is draining, loosen the trans cooler line on the left side, by the modulator valve. this will vent the convertor, allowing quicker draining. i leave the 19mm wrench hanging on the banjo bolt to remind me to tighten it.

[snik]

uh oh... i was turning mine counter clockwise now that i think about it... it has been driving fine though

[BENZDOC]

if a worn timing chain is present, turning it backwards can alter the timing...and that,s not good.... you r lucky, and probably have good chain components.. only turn an engine in the direction it was intended to turn...

[snik]

I will definitely keep that in mind. Thanks

Car has 135k miles on it now, & it doesn't make any chain noises at idle or any speed, so chain components must be in good shape as you suggested, I guess I am lucky nothing happened.

[Rainmaker]

Wow thanks guys for the great tips!

Snik -- those are awesome pictures, the pics are really a tremendous help!!!

Judging by the red fluid, I see you're using Dexron-III

thanks!
Rainmaker

[big dan]

That 'torque converter gear' is actually the ring gear that the starter engages to turn the engine over.
That's what those teeth are for.

It is very important to avoid turning the engine backwards when doing this job, as previously stated.

[VenezuelaBenz]

be sure to ONLY turn the engine clockwise (looking from front). very important......What do you mean by that??
What engine? Are you talking about turning the key clockwise?
Thanks

[Brett San Diego]