Replacing Transmission Soon, What else should I do?
 

I will be replacing the transmission soon on my '93 W124 300D soon and I was wondering what else I should consider doing while I have the old transmission out.

Right now my speedometer/odometer aren't working. This happened four days ago. I don't know if it has something to do with my completely worn out transmission or not.

I also have noticed that my injector pump oil leak is getting a bit worse lately. Is it easier to get to the bottom of the IP with the tranny removed?

I may have another oil leak in the area but if I do it's not much.

In fact, I don't leak/use much oil at all. I have to add about a quart every 5-7K miles. I usually change the oil at around 8K.

I already replaced shifter bushings.

The "harmonic balancer" on the drive shaft aft of the transmission recently rotted off while going down the road. I have asked about this before but nobody knew what I was talking about.

It is a very thick steel ring that is attached to a bracket in it's center via very thick rubber. The bracket is held on the drive shaft by the flex disk bolts.

I no longer have it attached to the drive shaft and I don't know if it will cause any future problems.

I have a new transmission mount that I will affix when I install the new(used actually) transmission.

Flex disks look very good.

I don't know what else to check.

Are you talking about the carrier bearing? Pictures? For my money, anything that was attached to the driveshaft, should be attached to the driveshaft. I would figure out what it was and replace it - for peace of mind.

It's not the carrier bearing. It's on the end of the driveshaft, right on top of the flex disk. Not sure why mercedes only sometimes uses it, I found one on a 190d the other day, maybe I'll slap that on my w123.

If you don't notice any vibrations then I wouldn't bother with finding a replacement.

No, it's not the carrier bearing.

It is literally a harmonic balancer of some sort.

It was attached at the front end of the drive shaft and attached with the bolts that attach the drive shaft to the front flex disk.

Nobody else with this car has mentioned that they had seen one or knew what it was.

I've seen them on 126s sometimes, maybe you can find one on an SDL.

They are balancers, MB balanced the drive shaft as a whole, everything between the two flexi disks, vital to mark them with pain prior to removal so they go back on the same.

They are quite rare, most prop shaft assemblies are good enough not to need balancing.

My 82 SD has it on the shaft. big honking thing. steel ring with rubber connecting it to the flex disk mount, I figure it's more for vibration quieting, than balancing. it must be for engine pulse evening, like a harmonic balancer on the engine itself.

The pics are for a 124.133.

There is a seal ring on the front of the transmission, item #18, part #018 997 04 47, actually, that is one of five different numbers, so make sure which one you need.

The other is of the drive shaft.

The harmonic driveline balancer is not shown in your diagram above. I saw one a few days ago laying in the trunk of a car at PNP. I have only see maybe a couple others there the past couple years.

It`s a massive looking thing, with rubber in the center of a steel ring assembly.

IF the OP`s is deteriorated and needs replaced, getting one from a JY might like buying a used Flex Dics from a junker.

Get the part # off it and see how much they cost from the dealer, or call Lee.

I have seen these discussed before in various threads and picture posted of them.

Maybe one of these will make my 4-spd swap smooth out some.

Note: i was looking again at the above pictures, the first pic item # 173 & 174 show a round circle with a triangle in the center. this looks like the balancer shape. not sure what this is in the pic.

Charlie

May be a good time to replace the rear crankshaft seal.

As stated above, repl the rear main seal. EZ in this car.

Is that between the torque converter and the transmission?

I can't find that part anywhere.(correction: I found it, crankshaft oil seal, rear)

I've heard of a rear main seal but I've never replaced one.

Is it between the transmission and the engine or is it just part of the engine that is accessible with the transmission removed?

I do have an oil leak somewhere back there.

There is always a drop forming on the torque converter "housing" but I assumed it was coming from the IP that has been leaking oil for a while now.

The torque converter itself doesn't have any oil on it so I suspect my oil leak is coming from somewhere outside the engine itself.

The transmission I'm putting on is a used one with 120K miles on it.

Are there any issues I should investigate on the transmission itself?

Remove the flywheel and you will see the rear main seal. Follow the instructions for installation of the flywheel fasteners.