drain plug wrench
 

I have a 1971 w108 with a 2.8L long 6. I need to change the oil and also check the diff. fluid. Both of these plugs, I think are the same. I called my local MB service dept. and was told that this was a 14mm hex. The problem that I am encountering is I can't find a hex (allen) that big. I've checked all local auto parts stores and local hardware stores, all with no results. The largest size anyone has is a 10mm. I'm assuming that the previous owner did not have this tool either, since the drain plugs and filler plugs are fairly chewed up, as if a pair of pliers or such was used. Anyway, any help would be appreciated.

Made in the USA. Cheaper (per piece) if you buy it in sets that contain it.

http://www.sears.com/shc/s/p_10153_12605_00942669000P?keyword=14+mm+hex

Benz has a special 14mm tool for these plugs, but you can easily make one buy buying a 14mm allen-key wrench and cut a 1" to 1-1/2" piece of the long end.
You then put that piece into a 14mm socket and the piece that sticks out of the socket will fit your plugs.. you can also use a 14mm closed end wrench on that stubie.. That allows for tight quarters.
The actaul Benz wrench looks like a wrench with the 14mm hex sticking thru the handle, just as the one I suggest.
See them on ebay.
http://cgi.ebay.com/ebaymotors/Mercedes-Hazet-Oil-Drain-Plug-Wrench_W0QQcmdZViewItemQQ_trkparmsZ65Q3a12Q7c66Q3a2Q7c39Q3a1Q7c72Q3a1171Q7c240Q3a1318Q7c301Q3a0Q7c29 3Q3a1Q7c294Q3a50QQ_trksidZp3286Q2ec0Q2em14QQhashZitem3ef4dcccd3QQitemZ270396083411QQptZMotorsQ5fCarQ 5fTruckQ5fPartsQ5fAccessories
And you still have the 14mm allen wrench for other jobs ...I bought a set of allens and cut 1" off all of them , so I have a set of these little stubbies to fit in each size socket..I am surpriized no one has made these as a packaged set, b/c they allow you to use your regulaer socket set as the drve for the Stubies.

14mm and 17mm are the most common size Benz uses......

There are good suggestions above, but I got mine from AutoZone. They sell a three-pack under their Great Neck brand containing a 12mm, 14mm, and 17mm.

Dittos on autozone, the plug on some of the differentials is a 14mm hex.

Here is what they look like when made from simple allen wrench cut-offs...just slip a socket or box wrench over the piece and you are good to go..very nice in tight spots..

Also a 14mm w/handle I made many years ago that has served me well...

I checked auto zone and they said they didn't have what I needed. (Those idiots). I will re-inquire and reference the Great Neck brand. I really appreciate the help guys. Happy motoring.

It's really hilarious to think AutoZone and the like have anything for low-volume German cars.

Check with real tool companies, i.e. your SnapOn man or at snapon.com.

14mm is a pretty standard size for German stuff--BMW uses it too.

That is where I bought mine last month. I think the set was about $9.

Well sure enough, Auto Zone did have the Great Neck set. The metric version was $2 more than the SAE version. So I paid $12. It was worth it. Unfortunately I now have to find a replacement drain plug for the rear diff. The fill plug is ok, but the drain plug is so chewed up it is almost unrecognizable. Obviously someone did not have a 14mm hex and used pliers, hammers, and flat screwdrivers to remove it. Shamefully, I had to also use the screwdriver and hammer to tap it out. I did rework it a bit and was able to use a 1/2inch socket extention to put it back in. I am gonna call the local MB dealer here and see if I can get another plug from them. Hopefully it won't be too expensive. Other than that everything went great. I got real purty oil in the diff. now. The next project is the tranny oil and filter. Does anyone now if those are hard to come by or no?