Bimmerfest BMW banner

1 - 20 of 30 Posts

·
Registered
Joined
·
694 Posts
Discussion Starter #1
I just changed my diff oil. When I removed the first plug (fill) it went "puff" and blew out a little oil.

The diff was under a slight positive pressure, which makes sense since it was warm.

BUT, I thought most diffs are vented, but I can't find one on my 530.

Is it vented or do I have a plugged diff vent?
 

·
Registered
Joined
·
2,511 Posts
No help here, I've seen pics of e39 diffs that seem to show a vent hole close to the top of the pumpkin, just above the right axle output flange.
 

·
Under the lift arms
Joined
·
12,899 Posts
It is not vented... and you ARE CORRECT... the positive pressure was due to the oil being warm...

drain from the bottem.. fill from the top hole (level ground)

Gl
 

·
Seek to understand,^Value
Joined
·
25,199 Posts
I realize all the liquid would pour out the ends of the axle if it didn't have seals, but, I wonder whether it's really air tight.
 

·
Registered
Joined
·
694 Posts
Discussion Starter #6
With no vent, it is air tight. (assuming seals are not leaking)

My diff was warm when I changed the fluid. I opened the fill plug first and it went "Paaah" and with a rush of air it spit oil on my glasses.
If it was not air tight, that wouldn't of happened.
 

·
Under the lift arms
Joined
·
12,899 Posts
correct, thats exactly what happen..

short story time :)

i learned the hard way on a piece of equipment called a Mixico (mixer) you can goolge image that if you wish... it a mixer that mix's in our case plastic resin's
The top gear box (also sealed) gets oil changes ever so many hours, and after its mixing process in which is spools up to 3500 or more RPM its left with the oil being quite hot...(which creates quite a bit of pressure in the case)

long story short... after being told to open the drain plug slowly i took an explosive warm oil bath to the face, TWICE in one night....

when thru three unifourms that night
 

·
Registered
Joined
·
2,511 Posts
If you can Google, you'll instantly find multiple posts about the e39 M3 and M5 diffs having vents or breather holes.

Some people express the view that the pumpkins have to be vented or they'll heat up and build enough pressure to blow a seal.

Plenty of people talk about breather tubes or valves for their diffs on other car/truck forums. Boat owners are said to risk getting water in their diffs if they back their truck too far down the ramp when unloading their boat.

Here's a thread from the fest, with a guy asking much the same question about the breather vent on his e46. It took him 5 years to get closure after plenty of doubters insisted he didn't have one.

http://www.bimmerfest.com/forums/showthread.php?t=488165

I've seen pics of the breather hole on early M3 models and it seems tiny.

[edit....]
Here's a link to an ebay ad for a bmw e39 diff cover (for the sixes). Scroll down the ad to see some large pix of both sides. It looks a lot like the one shown in the link above. Isn't that a breather channel, with the same pinhole opening on the outer/rear side?
 

·
Registered
Joined
·
694 Posts
Discussion Starter #10
pleiades: THANK YOU, THANK YOU!!!
I expected the diff to have some kind of vent and now I know mine is plugged.

I will crawl under my car tomorrow and clean out the hole.

Thanks again!!
 

·
Registered
Joined
·
694 Posts
Discussion Starter #12
Pics? Wish me luck.... You know how much room there is at the rear of the diff above the mounts. I hope I can get my hand in there with s small wire or something.
 

·
Seek to understand,^Value
Joined
·
25,199 Posts
Pics? Wish me luck.... You know how much room there is at the rear of the diff above the mounts. I hope I can get my hand in there with s small wire or something.
I second the notion that a picture would be a good idea.
Doesn't anyone own a cell phone with a camera nowadays?
 

·
Registered
Joined
·
694 Posts
Discussion Starter #14
I second the notion that a picture would be a good idea.
Doesn't anyone own a cell phone with a camera nowadays?
BlueBee, BlueBee... I guess you don't know how close the back of the differential is to the rear subframe. I think there is about 1" of room... My iPhone 6 (or any other phone) can't focus on objects that close.

I will try, but I expect the results to look like crap.
 

·
Under the lift arms
Joined
·
12,899 Posts
i was being sarcastic... i already got some hate mail from some tool name ca2014mp2 calling me out in a pm like a little bitch


but im going to let you guys figure this out on your own.. what that little hole really is..
 

·
Registered
Joined
·
2,511 Posts
i was being sarcastic... i already got some hate mail from some tool name ca2014mp2 calling me out in a pm like a little bitch


but im going to let you guys figure this out on your own.. what that little hole really is..


I still have a suspicion you could be right. I have no firsthand experience with it, and the pics I've linked to may be pointing at something that isn't actually open up to anything. So, let us know what you find there .... MAX_VQ .... in the name of science.
 

·
Under the lift arms
Joined
·
12,899 Posts
You gotta rap your head around what a diff is.. and how it works..

I can tell you with 1000% certainty that if this illustrious hole was in fact a breather... you would have build of of dirty and grease around it... like the fords and chevys... what the op experienced is completely normal

but i have no interest in getting off my ass to put my car on the lift (cause im sure as sheet not gonna get on my back)

This is kindda a waste of internet space if you think about it,,, what are we trying to achieve here? is there a mass blow out of rear dif axle seals out there that we need to worry about? come to think about Bmw rears hold up very very well.. there seals are superb, Ive gotten hundreds of thousands of miles out of them with out leaking axles or drive shaft input .... IDk.. im still trying to figure out why this is such a concern.....


i actually think its a part of the casting process,
 

·
Registered
Joined
·
694 Posts
Discussion Starter #18
This is kindda a waste of internet space if you think about it,,, what are we trying to achieve here? is there a mass blow out of rear dif axle seals out there that we need to worry about?

i actually think its a part of the casting process,
Waste of internet space??? Did my diff question over shadow critical news of people like the Kardashian's? :)

EVERY diff or transmission that I have worked on has a vent. It allows the seals to have a longer life, since they don't need to work as hard as pressure can't build up.
If my vent is unplugged, it may stop my diff from leaking.

Later today I will CRAWL under my car and try to see if that hole goes anywhere.
 

·
Under the lift arms
Joined
·
12,899 Posts
ahhhhhh......... and now i see why we are here..

because we think the diff is leaking because the "vent" is clogged...

may i ask where your leaking from? (there is only 6 spots it can leak from)

driveshaft input seal, axle left axle right rear diff cover gasket fill and drain
 

·
Seek to understand,^Value
Joined
·
25,199 Posts
I think there is about 1" of room...
I understand. I snap enough pictures to know.

But, I was hoping you could accomplish the task ...

expect the results to look like crap.
We are dutifully forewarned.

what are we trying to achieve here?
I think the title of the thread is pretty clear about the physical question anyway,
Q: Does the E39 differential have an air vent or not?
A: (either yes, or no)

If my vent is unplugged, it may stop my diff from leaking.
My diff has long-standing oil stains on it (yes, I will go and snap a picture with my Android phone for you).

I don't know what that means though without further investigation which I have never done.

I can fully appreciate the lack of desire to crawl under the thing though, just to find out why.

ahhhhhh......... and now i see why we are here..
because we think the diff is leaking because the "vent" is clogged...
It's interesting the approach you took, which was deeper than mine.
Mine was "does it have a vent or not" while yours was "why do you care?".

I think the answer to both questions are useful.

may i ask where your leaking from? (there is only 6 spots it can leak from)
driveshaft input seal, axle left axle right rear diff cover gasket fill and drain
Just as a side note, a good friend of mine owns a Tacoma which is apparently notorious for leaking drive shaft seals. Why? I don't know. Do they have a vent? I don't know. Does a clogged vent cause drive shaft seals to leak? I don't know.

But they leak all the time.
- Rear axle seals leak due to clogged breather
 

Attachments

1 - 20 of 30 Posts
Top