722.6 Transmission Service
 

You know things are going to go well when you crawl under there and the torque converter drain plug is smack dab in the center of the opening. That's a first for me.

This is as straight forward as it gets. Quick tool list: #30 Torx, straight slot screwdriver, 5mm Allen socket, 7mm deep socket and a 1 inch extension. Drain torque converter, drain pan, drop pan. If you have the new data plug receptacle (called a spacer), then remove the shield. Rotate the quick disconnect and remove the plug taking car about dirt particles. Loosen the 7mm holding screw in the center of the receptacle. You will know that it doesn't come all the way out, because you have the new one in your hand. Then use a small straight slot screwdriver to pry the receptacle out. You will see the place they designed just for this. Install the is exact reverse. Do not overtighten this little brass screw.

I have an inch pound torque wrench for the 124 tranny pan. This is a new design and brilliant.
Sort of a slotted casting around each bolt. When you tighten the bolt you really can't go wrong with a normal mechanic touch on the bolts. The design of the casting gets the pressure on the gasket exactly right every time. The various write ups on the internet say that the filter sits with nothing holding it up. Not true. There is a convenient plastic male
clip that snaps into the gap in the casting.

The locked cap on the fill tube is silly since anyone that really wants in need only press the red plastic thing down and it unlocks. I just pressed it all the way through and re-used the cap and locking pin. Works fine.

So I filled three, started engine, filled three more, and went for a drive of about 10 miles.
I stopped shot my infrared thermometer on the pan. 82C. Good enough. Had to pour about
1.1 more liters to get it perfect. I did use the MB fluid, but at $11.50 per liter versus almost
$18.00 at my dealer.

Condition of the old fluid? There was nothing in the bottom of the pan. The 124 usually had a very light grey film. This was pretty much nothing. Fluid had been changed at 67K at the dealer. Of course, the beauties didn't think they should take the time to drain the torque converter, and thus only replaced 5 liters per the receipt. Fluid was reddish brown. I wouldn't say chocolate. It didn't smell.

Shift quality. It was fine before, but marginally smoother after the change.

Steve
'97 S320 107K

Note from a nitpicker... I have read before the idea of measuring the trans temp with a IR thermometer. I own one myself. One important but often overlooked factor regarding the use of IR temp measuring devices is the emissivity of the measured material. As I recall, the pan of the 722.6 is aluminum. Aluminum has very low emissivity, ranging from about .02 to about .1. As such you will not get an accurate temp measurement with an IR device (unless it has adjustable emissivity setting and you set to the appropriate setting). Most are preset at .95. I ran into the same problem trying to measure some copper pipes in my house. My readings were very far off. I discovered that the emissivity of copper is similarly low. I solved the problem by spraying an area with flat black paint.

Mike

Pan is steel on the 722.6, matter of fact I don't recall an MB with anything BUT a sheetmetal transmission oil pan.
Gilly
(I'd still rahter see this done using the shop computer, they're really picky on oil level, but I know lots of folks here want to get DIY info.)

I bought the Infrared thermometer based on a couple of other posts. I don't know how accurate it was. Pan is steel and it is painted black. I think that
the transmission must have some tolerance. If not then why is are there two marks defining 80 degrees centigrade on the factory dipstick tool.

I drove it 10 miles and filled it between the marks, but not all the way to the top mark. Logic was 1 liter of cold fluid has some expanding to do. I doubt that most independent MB shops have the special computer that the dealers have to check fluid temperature.

I call it good and suspect it will be just fine.

Steve

Tech bulletin says (on the .6) to fill it to the top line. Not overfilled, just to the max line. Slightly better shift characteristics.
Gilly

Painted steel should work OK. Emissivity is .85 to .90 on the chart I have. If it is flat paint or dirty then it could be even better. I would be curious to see the difference between using the IR gun and what the computer says. It would be helpful to know the difference if any since the IR gun is a good way to go for DIY'rs. In any case probably plenty close enough although I don't really know.

Mike