What is the procedure for replacing transmission mount?
 

I did my transmission mount after the engine mounts by a couple of months. I don't think it really matters which order you do things in.

Put a thick board under the tranny pan and jack it up just enough to support it. Remove the transmission crossmember and the mount. LOL at how flattened the old one is compared to the new one. Install the new mount, then jack up the transmission enough that you can reinstall the crossmember and mounting bolts. Check tightness, remove jack and board. Have beverage of choice.

I usually just undo the transmission mount and jack up the tail. If you undo the engine mounts at the same time, that may be too many degrees of freedom. Do the engine mounts once the transmission is secured. When you lift, make sure you mind the transmission cooler lines, fan shroud and the radiator hoses. Safest to remove all that stuff, but it can be done with everything in place if you're careful not to lift too high.

You really should (but not absolutely necessary) loosen the large clamping nut on the drive shaft. It allows a bit more movement of the front guibo and reduces the amount of twist/stress the guibo receives.

I disagree with Diseasel300's advice. This is a TWO beverage job!

If you have engine shocks, release one end before you life the engine.

Sixto
98 E320s sedan and wagon

Anything different about doing say the transmission mount on a manual 1981 240D?? Other than the witchcraft needed to figure out which part number the manual transmission mount really is of course....


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Nope. Check for clearance on the cooling fan blades as the OM61X series are notorious for collapsing the LH side mounts due to diesel fuel and power steering fluid leaks.

Found this tutorial online for changing out the motor mounts....
 

nice tutorial with photos....

https://www.ifixit.com/Guide/Mercedes+W123+Motor+Mount+Replacement/20760

Don't loosen the engine mounts. That is difficult and unneeded. Support the transmission on a jack w/ wide board under the tranny pan and newspapers to distribute the load. Lift it just 1/8" to relieve force on the tranny mount. As I recall, you must unbolt the short "cross-member" get the tranny mount out since it sits down in a U channel.

Don't forget to disconnect the throttle linkage BEFORE you lift the engine...and also disconnect one end on each of the the engine shocks as advised by Sixto.

Place cardboard bewteen the radiator and fan to protect the radiator fins from damage by the lower fan blades tilting forward as you lift the engine.

Here is a direct link to the free W123 FSM hosted by MBUSA.

Took of throttle linkage......question.
 

No, other than to lubricate the linkage with a little ATF...since it is more accessible.

Do the mounts one at a time. I suppose you could loosen the mount bolts a little (a very little), but don't disconnect more than one mount at a time. Too much unnecessary movement will make it hard to line back up. That drive train is Heavy.

I didn't have to drop the crossmember to do the tranny mount in my 84 300td. I just took the bolts out, jacked the trans up and changed it out.
Just obviously don't jack it up more than you absolutely have to.