Oil below airbox

[Olive]

Hi all. Two days ago I went for a simple service check and as soon as the car has been placed on the bridge we saw some oil traces.
After had removed the carters we found some oil all around pieces N°5, all around direction bocal, and also a small quantity inside the carbon box, where the hose n°3 is plugged :


http://ills.bmwfans.info/199d.png


I called a well known specialist in France to get his opinion. It seems that CHF is not concerned. It is not sticky and not red, looks like oil (clear).
For him it is probably the hose n°3 who is dead. He also advice to change piece n°1 (oil separator).

Did you ever met this kind of trouble ? Do you have an idea ?

This hose n°3 is plugged on the airbox, I am not a specialist (far from), so could someone explain to me why is there a link with oil? What is the purpose of this hose ?

Thanks and sorry if I am not clear, a technical mail in English is not simple to write for me :)
http://fr.bmwfans.info/parts-catalog/E46-Coupe/Europe/M3_CSL-S54/L-N/feb2003/browse/engine/crankcase_ventilation_oil_separator/

[CraigMillwardCroft]

Where does 5 go from too

[Mark CSL]

i am sure 5 goes back to the sump its a breather system


the small amount of oil in the air box is normal

[Chad]

i am sure 5 goes back to the sump its a breather system


the small amount of oil in the air box is normal yes seem to remember it goes to the sump case next to the dipstick ,,

[Olive]

The diagnosis given but my mechanic seems to be good for you ? Hose 3 to replace?

[select]

Hello Olive,

First.. the Oil lines are there for when the oil gets hot, it evaporates a bit. Normally you would just make it exit the engine for good or make it go into a canister (catch can) but because of regulations it is forbidden for any Oil to permanently exit the engine, so the engineers made it so the oil gasses get diverted into the induction airbox. So basically the engine is designed to inhale its own blow-by gasses.

So a bit of oily-ness inside the airbox is perfectly normal, however it shouldn't have puddles of oil in there.

In your case i think that some pipe going to the underside of the airbox must be leaking? I think a gunked up oil seperator is not the issue, but im no car mechanic, so take with a grain of salt.
It is however not very expensive to replace (around 100€) and should be done at around 100.000km anyway, imho.


I would disconnect the pipes you've mentioned and check whether they still are free. And if in doubt replace them.

[Olive]

Thanks a lot Julian for this clear answer. I will let you know the news tomorrow 👍:beer:

[select]

You're welcome mate. :thumbs:

[Olive]

I received a picture from the garage.

On collar was missing (normal ?) on this small hose, the collar bellow has been added by the garage.

https://zupimages.net/up/18/37/wu52.jpg (http://zupimages.net/viewer.php?id=18/37/wu52.jpg)

It seems there is no problem with hoses anywhere. Do you think it could comes from here ?

[Olive]

One more point.
The garage asked me about the tightening torque of the rear axle input nut. This is the one that holds the shaft of attachment of the shaft of transmission.


I know...I am not very clear. Here the piece I am looking for the torque :


https://zupimages.net/up/18/37/qtfq.jpg


Somebody ?:beer:

[Chad]

One more point.
The garage asked me about the tightening torque of the rear axle input nut. This is the one that holds the shaft of attachment of the shaft of transmission.


I know...I am not very clear. Here the piece I am looking for the torque :


https://zupimages.net/up/18/37/qtfq.jpg


Somebody ?:beer: hi olive don’t think there is a torque for this ,, there is a crush washer/ bush Behind it’s more to do with setting the load on bearings , Definitely wouldn’t over tighten,or possibly end up with groaning bearings,, you could probably just take up the play on nut and lock back in place,, this nut is normally done when setting up the diff ,, I’d imagine if it’s really loose possibly bearings are a bit worn

[Chad]

One more point.
The garage asked me about the tightening torque of the rear axle input nut. This is the one that holds the shaft of attachment of the shaft of transmission.


I know...I am not very clear. Here the piece I am looking for the torque :


https://zupimages.net/up/18/37/qtfq.jpg


Somebody ?:beer: hi olive don’t think there is a torque for this ,, there is a crush washer/ bush Behind it’s more to do with setting the pre load on bearings on pinion gear before installation of lsd , Definitely wouldn’t over tighten,or possibly end up with groaning bearings,, you could probably just take up the play on nut and lock back in place,, this nut is normally done when setting up the pinion in diff housing ,, I’d imagine if it’s really loose possibly bearings are a bit worn,, I believe pinion bearings preload is 12-23 inlbs, But this isn’t the nut torque

[Olive]

Thanks a lot Chad!
Is it 12/23 inlbs or 12/13 ?

[Chad]

Thanks a lot Chad!
Is it 12/23 inlbs or 12/13 ?. 12 - -23 This is the rotational resistance on the bearings. To ensure they’re not to tight or running loose. Not the torque on the nut,, Could be different on different manufacturers bearings. But in the ballpark. Nut on mine was loose I just nipped it up at the time and locking it in ,,, probably most end up on the loose side as bearings wear. Unless it’s really really loose probably not a big issue.. pinion is shimmed to obtain correct set to crown gear on assembly,, I don’t claim to be a expert. But have some knowledge after doing my own diff work :whistle:

[Olive]

May be you are not an expert but comparing to me it looks like the same :thumbs:

Thanks a lot.

[select]

Sorry for late replay, regarding your question about the collar.


Its difficult to guess whether that missing piece could be the culprit.
Because usually those connectors on the hoses are very firmly and tightly attached to the airbox. So i don't believe that a missing collar and therefore a bit of play on the hoses (not on the connectors) themselves would cause a leak.

Usually those clamps only function is to keep hoses/pipes from dangling about and to keep them grouped together, so they don't get struck by moving parts.


Did you check if the plastic connector is ok? And if you connect the hoses to the airbox and you wiggle a bit on the hose, if its still firmly attached?

If you attach the hoses they make a firm "click" noise.

[Olive]

Honestly I did not checked it my myself. The car is in hands of my mechanic. I am gtransmitting to him all your advises every end of days :beer:

He ordered piece n°1 + some others small pieces. We'll see...