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Hi, instead of another topside engine oil change I decided to do a traditional one where you drain from the oil pan. Usually do the topside so I accidentally took out the wrong bolt (pointed out in the pic) and drained the wrong thing
About 600ml came out and it felt and smelled like a gear oil. It was a slippery grey/blackish fluid.
My car is a 2012 W221 S550 4Matic.
Would anyone be able to tell me 1) what this is (I think its the front axle differential) 2) how to fill it back up 3) what type of fluid to fill it back up with 4) if 600ml is the right quantity of if it is one of those units you fill until the upper hole leaks out etc.
As a follow up after some online research, not a lot on this model but just in general I have derived the following:
- It's the front differential that holds a capacity of 550 ml
- Takes Mercedes Hypoid gear oil (85W-90)
I also don't believe there is a filler hole from what I've read so I'm going to use my oil pump I have that I've used to pump oil into other diffs etc, make a seal and pump about 600ml back through the drain plug hole and then quickly pull the tube away and plug the hole back with the drain plug. Might spill about 50ml doing that so end up with 550ml.
Sounds kind of ghetto but figure it should be in the same position as before with the fluid back in. I happened to have the new fresh fluid here by luck (not pumping the old drained stuff back in). Looks like the torque for the drain bolt is 14.7 ft lbs.
I'll do this later on today or tomorrow. Wondering if I am way off base trying this out?
That reply was useless, obviously you don’t know either, honestly just don’t reply at that point.
Anyways, since the drain hex bolt was removed and ~550 ml came out, figured if I reinsert this same amount and put the fill plug back it should be back to where it was before.
I pumped 600ml of Mercedes Hypoid gear oil into the drain hole, removed the tube from the pump and covered it with my finger, then removed my finger and installed the drain bolt. Probably spilled about 30ml or so doing that which left about the same amount as drained back in the front axle differential.
Car drives great and has fresh oil in there now as well as the stuff that came out seemed to be worth changing.
If anyone has any other feedback I’d really appreciate it. Knowing what I did was ok from someone who knows that they are talking about would be great.
If anyone has any other feedback I’d really appreciate it. Knowing what I did was ok from someone who knows that they are talking about would be great.
Thanks.
No idea what I'm doing, but I think you've got it right. It looks like the only other port on that front diff is the vent on the top, perhaps it could have been filled through that?
There are good photos of a new unit here on eBay, black cap is the vent (Top of the unit) where the drain plug you found is the bottom.
Thanks a lot, not sure if can be filled through there as well. I talked to the dealership today and they said that's totally fine if I pumped the proper gear oil and amount back in and just sealed it back up
Yep, filling is done with the axle pulled out and as such, the front diff isn't considered a service item, you only replace fluid if draining it to remove or repair.
Thanks very much, appreciate it. So ideally it's filled via the front axle shaft opening when reinstalled if a repair or replacement is done. Does that mean it has to be filled that way, or is that just the ideal (obviously) way to fill it when reinstalling. I wonder alternatively if re-inserting the fluid via the drain hole is also fine if you did nothing else to the unit (ie accidentally drained it) with the called for 600ml, as it would seem then the 600ml is also sitting in there whether it was filled from axle shaft opening or the drain hole.
I'd like to avoid having that whole procedure done via the axle shaft just to put the gear oil in there as it currently is right now already.
Nothing to worry about Canada, everyone makes mistakes.
To me that looks like a front transaxle or transfer case. Regardless, there should be a fill plug on top. Do some research on both and see if you can pull up some pics to identify exactly. You can also find out what fluid guys recommend or use.
Great opportunity to do some preventative maintenance anyways. No biggie.
And now we all know that he has a 4matic......... Yep, filling procedure is as described, i would not pump in the 600ml with an air pump since there is NO exit from the air that is already inside..... You might get lucky and not damage anything but you can also break a seal somewhere..
And now we all know that he has a 4matic......... Yep, filling procedure is as described, i would not pump in the 600ml with an air pump since there is NO exit from the air that is already inside..... You might get lucky and not damage anything but you can also break a seal somewhere..
Beco
There is a vent on the top of the diff, so the air will come back out just fine.
Went on a nice long drive today about 100kms different speeds and terrain, parking lots, full lock turns etc. Drove very smooth and never heard any out of the ordinary noises (like the howling noise the service bulletin in one of the links I posted mentioned if it’s having issues etc).
Given it seems to be fine and it being a major job to just fill again via the axle I’m going to leave it. I’ll report back in if I ever run into issues but the car seems to be perfectly happy.
Given it seems to be fine and it being a major job to just fill again via the axle I’m going to leave it.
If you drained the fluid out of you front differential or Transfer case, and didn't refill it, "leaving it" would be a HUGE and costly mistake.
Also, it is NOT a major job at all. If you don't want to get to the fill plug (which shouldn't be hard) simply get a fill bolt adapter that attaches to the drain and a $6 pump and pump the new fluid in.
Whatever you do, don't drive it with no fluid. Go ahead and look up the cost of new frond diff or transfer case and labor associated with it.
Hey there, sorry for the confusion if you read above I did fill it through the drain hole with exactly the same amount and type of fluid that came out and then sealed it back up with the drain bolt. I used one of those hand pumps that held 600ml. The car never moved while it was dry, agreed that would be a disaster.
My dilemma is that I filled it through the drain hole vs the axle shaft and was hoping it didn’t matter.
05-13-2018, 05:26 PM
