Rear end pinion seal on 1984 300 SD
 

I've got oil leaking out of the differential housing from the front (behind the flange). I bought a replacement pinion seal MB part # 025 997 00 47 at the dealership here and asked about the pinion nut wrench (tool to remove the nut holding the flange onto the diff) (? not sure if I understand how it all fits together, if I'm wrong, please let me know). Someone told me that MB makes a special tool just for that use and I should use it after removing the three bolts holding the pinion to the flange and before pulling the flange (so, where do I get a flange-puller for that size, anyhow, and what is it called?). Well, today the MB Direct Parts people in NYC told me that that tool isn't avail. in the US. :confused: And, I emailed mercedesshop about this and other things and was told that "You should be able to get this from any tool company. If you can get the nut size, I'm sure we can supply it." So, which is right?

Thanks.
:D

Edited for P.S.: Was planning on jacking this up, onto jack stands, get under Hilda, open the hexagonal socket plug on the right back of the housing and stick a mangetized screwdriver in there to see if any bits of metal stick, replug the plug, move back to the front of the housing, undo the bolts holding the flange on shaft, pull the flange (:eek: what do I use for this?), use the special MB magic tool which may not exist to remove the nut, open it up, remove the seal which is probably shredded, put on the new seal I got at MB, close it up, reattach the nut and then the flange, go to the back and add 80W90 gear oil to the housing ...but the car will be on an angle so I don't know if I'll be adding too much ... and then replace the plug. If I had found lots of metal in the oil at the beginning, I'll call the mechanic and make an appointment.

Is that how it goes?

Here's what I remember from a couple of years ago when I did this.

I ended up making the tool from an old socket. I think it was an inch and a quarter??? Filed down the rim of the socket to fit the slots in the nut. You will need a new nut because the old one cannot be reused. When it was installed by the factory, they punched down the lip to keep it from coming loose. Had to take a punch to remove the piece that was punched down and then was able to remove the nut.

As for the flange it does not require a puller, it slides right off once the nut is removed. I'm assuming by the flange you mean the three armed gizmo that attaches to the flex disc. You'll have to drop the drive shaft to get to flange. Might want to inspect the flex disk(s) while you have the drive shaft off. Like all the rubber parts on the Benz they go bad on these old cars.

JV

jonvee,

Can you find that socket and tell us the size?

Hi
A friend of mine helped me change that seal on my diff, an 87 300d, (124) . On that it was a 30mm socket and he had to lengthen the socket for it to fit over the pinion properly.
This he did in a lathe, parted (or split the socket in two) and then welded in a length of tube as an extension.
better make sure from someone else though.
gerard

I've attached a pix of the nut. The outer diameter is one and a half inches. You can file down the edges of the socket, ending up with four prongs to fit in the four slots of the nut. Buy one of the cheapest sockets you can find. Makes the filing easier because of the cheap metal they use to make the socket.

Also notice the section on the inner rim of the nut where I removed the piece that was bent in to secure the nut.

JV

Thanks,

I'll look out for a 1.5" OD socket at my next flee market.


Michael

Hey jonvee!
 

About that socket tool: how long is it? I would prefer to avoid any welding.

Thanks.

The steps are :

Drain the oil,

Drop the rear end of the driveshaft,

punch the edge of the nut,

remove it with the tool,

remove the seal

clean up and pass a strong magnet around to remove any bits of steel,

install the new seal

install the new nut

fill with gear oil.

I observe that Mobil-1 makes a synthetic gearlube (smells as funky as the dino stuff), and that it is probably worth the three or four buck extra.

THANKS!

Hey jonvee!
 

About that socket tool: how long is it? I would prefer to avoid any welding.

Thanks.

The steps are :

Drain the oil,

make the tool, using the new nut as a template,

Drop the rear end of the driveshaft,

punch the edge of the nut,

remove it with the tool,

remove the seal

clean up and pass a strong magnet around to remove any bits of steel,

install the new seal

install the new nut

fill with gear oil.

I observe that Mobil-1 makes a synthetic gearlube (smells as funky as the dino stuff), and that it is probably worth the three or four bucks extra.


It will probably spend a really long time in there.

THANKS!

Standard socket about 2 or 3 inches deep. The four prongs are 1/2 to 3/4 inches. I used this on a 126 model. No welding, no lathe!

Yes, the synthetic gearlube is worth the extra money. If fact, you might want to change it after a couple of weeks as it really cleans all the old gunk out.

JV

I know this is late but for future searches.

This is the tool you need

http://www.samstagsales.com/SirTool/stm_0026.htm

And this is the company to check for future tool finding problems. However you may not like the prices.

http://www.samstagsales.com/mercedes.htm


Dave

A picture of the tool

Dave

Dave,

Since you're in Colleyville, I'll just come by and borrow yours!

JV

The dimensions of the Sir tool M0026 are:
A = 41.50mm (length)
B = 35.00mm (diameter)
C= 7.50mm (probably the depth, but this seems unimportant)

They want $59.95 (American dollars!), plus shipping for this, which means I will pay a visit to the pulguero (flea market) and buy an old socket to furgle, thereby saving time and deutschmarks, euros, whatever. I have a grinder and will be on the lookout for a fine Asian socket to grind.


Thanks!

tightening up the nut
 

I hear no mention above on how to re-tighten the nut - I recall somewhere that under the seal is a collapsible seal which if the nut is overtightened will collapse - ?
Steve

Call it dumb luck, but I didn't see any other seal. Looked like a generic seal. I just tightened the nut to the specified ft-lbs and it hasn't leaked since. (3+ years)

JV