transmission in s 420
 

there appears to be some seapage of transmission oil from the area where i have been told the "electro-hydrulic connector" entered the tranmission. this unit is on the right front of the tranmission. there are wires connected to the unit. there is a tin sheild protecting the unit. i was further advised this unit has an "O'' ring seal. if my information is correct how do i remove the unit to replace the ''O'' ring? also is a dip stick available for checking the fluid? i read the operaters manual and they advised the system was sealed and needed no checking unless a leak or shifting malfunction occurs. in my interest to investigate where the dip stick would normally be i broke off the red tab on the cap in order to get the cap off. i don,t believe much fluid has been lost at this time because i have been able to blot it up with a paper towel . the car is a 1999 with 88186 miles. as always your help is greatly appreciated.

The part has two O rings and has been redesigned two or three times. Buy the whole part that comes with the O rings. Cost is only about $15. There is a small hex head bolt holding the unit in place. Bolt is accessible once you separate the two parts. Just twist and pull the two halves apart. Have a container ready to catch a pint or so of ATF once you pull the old unit. Definitely check the fluid level after you replace the unit. Actually if you haven't serviced that transmission, you may want to do that. That way the fluid will be drained when you change the part and it probably needs serviced if you've never done it. Dipstick is available on e-bay. El Paso Tools is a good source.

To add to what Len said, MB has now decided the trans does not have a lifetime fill and does require service. I think the recommendation now is to change fluid and filter every 40-60k?

You do need to use only MB fluid, either for the 722.6 (your trans) or for the newer 722.9 G-Tronic trans whose fluid is backward compatible with your unit and is also a few $ cheaper than the original fluid.

The dip sitck is a factory "tool"; you'll need to get a new red lock too or the cap WILL vibrate off. Ask how I know....:o