300SDL transmission servicing
 

I've ordered a transmission filter and pan gasket today and in advance preparation have a few questions pertaining to servicing the transmission:

1. I've came across a thread in which one 300SDL owner was having issues with shifting (mine does not), and they spoke of cleaning out strainer filters in the (removed) valve body. I assume while I am in there that this is a good preventative maintenance chore? If so, is there any other gaskets or seals that I will need to replace in the process?

2. Not knowing what type of transmission fluid I am currently running, I assume that doing a complete fluid change is in order. Is draining the torque converter fairly straight forward? (Is the drain plug on it reasonably accessible?)

3. And on that note, what fluid is recommended to replace? (It seems that Mobil 1(?) ATF may be a good choice if MB fluid is not readily available?)

4. And is there a refill/startup procedure to follow? (I know over filling can be an issue...)

5. Anything other recommendations/suggestions that I should be aware of...?

Thanks in advance,
Andy

1. No way, do not attempt to mess with or take apart the valve body, you'll end up with a driveway full of small parts, and you'll be crying. I've never heard of such "strainer filters"....and they do not appear in the transmission schematics. The main filter catches everything prior to entry into the workings of the transmission.

2. Yes it is always good to do a full fluid change. To get to the (5mm allen style) drain plug on the torque converter, you need a 27mm socket to rotate the engine (CLOCKWISE ONLY) to position the plug in the small "viewing window" on the bottom of the front trans housing. A cheating method is to use a flat blade screw driver and pry against the torque converter to slowly turn it to the right spot. Either way works.

3. Mobil 1 ATF is not ideal, as they changed the formulation and it is no longer recommended for these transmissions. Valvoline Dexron VI Synthetic works well (I use this in all of my cars), as does normal Dexron III of any brand, or AMSOil ATF, etc...or the MB fluid, but it is quite expensive.

4. To properly fill the transmission you pour in 4 quarts, then start the engine, and while idling, pour in two more....then shift from reverse to drive a couple times, drive around the block, and check the level.....add more as necessary to fill to the correct level. (Usually this takes about 6.8-7.3 quarts)

5. Have a lot of shop towels ready, as it is a messy and gross job. Don't get any dirt in the transmission, it needs to be SUPER clean. Clean the pan out extremely well, use a new pan gasket, new filter, and new aluminum or copper washers on the drain plugs. Replace the drain plugs if they are getting rounded out. Use a high quality 5mm allen socket or allen key to prevent rounding out the plugs. Torque the pan bolts in a criss-cross pattern to the proper torque (this is important or it will leak). Pan bolt torque is 8nm (about 6 foot pounds).....drain plugs are 14nm....about 10 foot lbs.

Servicing the transmission (fluid and filter) is a lot like brushing your teeth. Removing and opening the valve body is a lot like a root canal. Don't even think about it.

... will avoid the "root canal"...
 

Thanks guys for the tips.:)
I have an extra drain plug and plug gasket on my order too (just in case...)
And I will leave the valve body ALONE....:thumbsup:

When washing out the pan, do not use a rag to wipe it out. the lint from the rag can mess things up.

I just clean it out with carb cleaner or brake cleaner and let air dry.

That is good info from above. :thumbsup:

Charlie