2008 Z4 3.0si differential fluid change info needed

[Lovebandit64]

Hey all, I want to change out my diff fluid but I am not allowed (by my lease) to do it in my driveway (I live in the lower part of a house with my landlord upstairs). I have got the fluid but now I read that I need to buy new plugs for the drain and the fill holes...IS THAT TRUE? Or is just a new drain plug needed and I can reuse the fill plug?

Also, will any make 14mm male hex socket work or do I need something special like this one?: https://www.turnermotorsport.com/p-5...lug-tool-14mm/

I also plan to have a local quick oil change place do it for me (I know the manager there) so I don't have to do w/o the car for a day. They said they could do it but they will be doing it with the car over a hole in the garage-bay with the wheels on the ground. Will they have adequate access to the two plugs or does the car have to be off the ground?

I really need answers because I do not want to take the car in to them and have them not be able to do it for some reason or another....

Thanks so much for any insight you can give me.
JC

[Efthreeoh]

You don't need to get a new drain/fill plug, just reuse the old ones. The trunk box makes getting to the fill plug a bit difficult. I have a 14MM Allen Snap-on socket that I use. There's not room to use a ratchet with it because there is no room to attach it to the socket; however you can use a 14MM wrench on the Allen shaft of the socket. The plug is blocked a little by the rear framing, but nothing terrible.

[Karacticus]

It would be a surprise to me if you actually have a drain plug. My coupe's a 2007 and does not have one-- I use a air compressor driven suction device to remove the fluid.

[Don L]

True no drain plug. Had to have the fluid sucked out when I had mine done.
Dealer wanted to pull rear end out. Haha.

Don

[GuidoK]

Originally Posted by Don L

Dealer wanted to pull rear end out. Haha.

Don

He shouldnt be allowed to do that. BMW dealers have to follow TIS instructions and there it says to suction out the oil. Offical dealers must have all the tools in house to follow TIS instructions.

As for getting the rear fill plug out, I use a special 14mm hex bit.
Not a socket type, but an insert type which I use with a small wrench (9 or 10mm I believe.
Something like this:
http://www.ebay.com/itm/14mm-HEX-KEY...-/161031688526
this gives you lots of room as its easily the most compact setup I think.

A normal 14mm hex socket plus 1/4 or 3/8 ratches is usually too long. I also have a normal 14mm hex key (the normal angled style) but even that is too long on the short side.

You also need some sort of pump to fill the diff. I use a large oil syringe (with a piece of hose) for that.

I reuse the plugs and their aluminium seal rings.

[The HACK]

http://www.realoem.com/bmw/enUS/show...diagId=33_1309

According to this, the drain plug comes with a rubber o-ring. I wouldn't chance it. Might work, might leak. Most drain and fill plugs on BMWs are one time use only now. Even OLDER BMWs require that you replace the crush washers (now replaced by rubber o-rings to make the drain and fill plugs lighter) when you change transmission and diff fluid.

And yes you need either a super stubby diff hex key socket, or you have to cut a hex key socket off. There's not enough room in there to put a torque wrench (and yes you need to torque it to a specified "tightness") and a regular sized hex key socket.

Not sure if this is any indication, but the kit as pictured here comes with 2 diff plugs:

https://www.ecstuning.com/b-assemble...3117512980~kt/

Now, the cover appears to have only one hole (fill hole), so I suspect the drain hole might be on the pumpkin itself.

[GuidoK]

I'm wondering what partnumber those plugs are.
On my diff they're certainly without o rings (I had them in my hands today as I'm currently working on my diff) and that partnumber hasnt changed yet since 2003, so you'd think that those parts are still the same now. Usually any change in part (construction, supplier etc, also gets a new number)
I think its a strange construction to use both an o ring and an aluminium crush washer, as the crush washer seals on basis of deformation, which requires imho more torque than o ring pressure can provide. Or that thin outer lip gives te deformation.
On the gearbox the plugs with o ring are used without a crush washer, which makes more sense to me.

As for the aluminium rings (and plugs without the o rings) I've used them (the same ones) at least 5 times and always without leaking (or without the use of a torque wrench), so apparantly I'm doing something right. Pretty fool proof system if you ask me.

If there's a drain hole present, its certainly on the diff housing and not on the back lid.

[Lovebandit64]

I was just assuming there is a drain hole on my 2008 3.0si due to this post:

http://www.zpost.com/forums/showthread.php?t=79742

Thanks all!!

[GuidoK]

So I did some more digging in TIS about those plugs, and TIS has 2 procedures, both the plug with o ring and without o ring are described.
Both have different torque settings (with O ring: 60Nm, without O ring: 65Nm) which is not that strange (and they are pretty similar), but the strange thing is: the one without O ring is mentioned with the aluminium crush washer (which is expected, and they say: change crush washer, also expected), but the plug with O ring is mentioned WITHOUT crush washer! No crush washer is shown or mentioned, and they just say change plug with O ring.
So how does that ECS kit work? It is shown with the plugs with o-rings and also crush washers...
So my conclusion is look at what plugs you have and what state their in. if damaged: replace. Replacing never hurts obviously but isnt always stricktly necessary imho. Maybe the O rings are more age sensitive alhough the plugs with O rings on my gearbox still looked fine (O ring still compliant) and I didnt replace them and there are no leaks.
Be sure when you use the plugs with O rings, to lubricate the o ring with a drop of oil before fitting the plug.

[rsutoratosu]

I did mine many times, just make sure you open the filler first... if it doesn't open and you drained it.. you are SOL

[3002 tii]

My 07 doesn't have a drain plug

[rsutoratosu]

have a pic ?