W123.123 need advise on Front Main Seal - PeachParts Mercedes-Benz Forum

BiodieselMB · #1 10-22-2014, 01:04 PM

Hello,
Currently involved with my 1983 240D. Beautiful car

W123.123 need advise on Front Main Seal-w123.123.jpg

Please help me get started with the front main seal replacement job. I have not performed this operation before and need some encouragement.
The car is working great in every way and I do not want to mess it up.

Dan Stokes · #2 10-22-2014, 02:21 PM

Assuming it's like the 617 front seal (pretty sure it is) it's just a standard one piece lip seal like most American engines. Piece of cake = it pops out from the front and you put a SMALL amount of sealer (anerobic works well) on the OD and carefully tap the new one in. You'll have to remove whatever stuff is on the front of the engine (alternator, PS pump, etc.) and pull the vibration dampener. When you pull the dampener check the surgace that the seal rides on - it needs to be smooth and flat. Small imperfections can be polished out with emery paper but gouges will need either a new dampener or, if available (I haven't looked) a repair sleeve.

Dan

BiodieselMB · #3 10-22-2014, 03:45 PM

thanks for getting me started. will i need to remove the radiator?

Simpler=Better · #4 10-22-2014, 03:57 PM

You can flip the sleeve, it will make sense when you do it. The accessories can stay on but the fan&shroud will need to come off at the very least. You will need a pulley puller.

BiodieselMB · #5 10-22-2014, 04:10 PM

thanks again. i will start pullin it apart

engatwork · #6 10-22-2014, 06:03 PM

I would recommend removing the radiator.

The hardest thing you will run into is loosening/tightening the harmonic balancer fastener (27 mm) because you will need to hold the crank. I made a tool that I'm able to insert into the flywheel teeth to hold the crank from turning while performing this task.

BiodieselMB · #7 10-23-2014, 10:52 PM

have ordered new pins and bolts on the advise of a few other postings. some say that its okay to reuse but it may be another 30 years before its disassembled again. will try the reversing of the sleeve trick to save a few bucks. and will try the plastic cup trick to insert the seal as not to bind up the spring.

toomany MBZ · #8 10-28-2014, 08:26 AM

No need to remove the radiator, just be careful. You will probably need a modified 10mm box wrench (see attachment) to remove the fan. The most difficult part of this procedure for me was getting the shroud and fan out. Removing the radiator may help there, your call.

You may want to replace the spacer ring also. If it has been worn, a new seal will leak.

MB makes a special tool for the spacer ring removal, but folks have been successful merely prying it off.

Good luck and keep us posted.

Stretch · #9 10-29-2014, 05:14 AM

Go and find a flywheel lock

Some reading =>

PeachPartsWiki: Replacing Front Crankshaft Seal with "Special Tool"

toomany MBZ · #10 10-29-2014, 06:16 AM

I use a pry bar wedged into a slot on the front, rotate the engine by hand (clockwise as you stand in front of it), you'll see it.

Stretch · #11 10-29-2014, 08:54 AM

Quote:

Originally Posted by toomany MBZ

I use a pry bar wedged into a slot on the front, rotate the engine by hand (clockwise as you stand in front of it), you'll see it.

Well you'll only get overseas tut tut tutting and cluck cluck clucking from me about that one toomany! You might come a cropper doing that kind of a thing - that front crank bolt has got a mega torque spec! But I do realise that times is hard - you can't always use the ideal tools...

toomany MBZ · #12 10-29-2014, 09:53 AM

Yeah, I do like tools, (bought the breaker bar and socket at the local speciality tool store, around $80.00. Not to mention the special $200.00+ MB spacer ring removal tool) but use what I have on hand when necessary.

The cheater pipe is from my now deceased floor jack, only thing big enough.

ROLLGUY · #13 10-31-2014, 11:25 PM

Believe it or not, I have used the following method with great success for removing the crankshaft bolt: Use your longest breaker bar on the 27mm deep socket and place it on the nut with the bar pointing to the right (when looking at the front of the car) just below the trans cooler line. Without glowing, crank the starter for just a second. The end of the breaker bar will hit the floor and loosen the bolt with ease. I have also tried a bar (a long 1/2" extension works great) in one of the balancing holes in the crankshaft hub with great success. This works for tightening if the end of the extension is supported on a concrete block or jackstand.

BiodieselMB · #14 11-08-2014, 07:24 PM

still putting it off. great information from you all.
i washed the engine and oil leak from that area is not as bad as i thought, but the job will happen and i will keep you informed. it is comforting to have the car in one piece and ready to go, and i know that when this job starts that it will be down for awhile with various other chores to do such as tracking down a suspension noise and oil leaks and then to do a valve adjustment for the first time.
will keep posting. thanks again.