I noticed a leak from the underside of the expansion tank. After removing it to repair I notice an outlet on the underside which fits into a rubber grommet, which then protrudes from the underside of the tank holder frame. I can't figure out if this is supposed to connect to a pipe of some sort or if it is just some sort of drain. I've tried finding a diagram showing it but with no luck. Any assistance would be greatly appreciated.
Gordon
Not joined yet? Register for free and enjoy features such as alerts, private messaging and viewing latest posts and topics.
Expansion Tank leak
Expansion Tank leak
Level sensor? That fits underneath but can’t remember exactly where. Should be a ‘twist-fit’ into a sealing grommet.
Never anthropomorphise computers. They hate that.Expansion Tank leak
No, I've already reconnected the level sensor. The problem is I've found loads of diagrams but they are all of different designs of tank, except the type I have.
Gordon
Gordon
Expansion Tank leak
If you haven’t already tried, have a look at RealOEM and see if there’s a clue there. It’s the BMW parts database. Use the last 7 of your VIN to pull up the right variant. Mine had a large 7.8L tank.
From memory it had a feed to the rear windscreen, one to the front windscreen and one to the headlight washer system but those were along the edges. Nothing else underneath other than the level sensor.
Leaks were either the pump/level sensor seals or a split seam.
From memory it had a feed to the rear windscreen, one to the front windscreen and one to the headlight washer system but those were along the edges. Nothing else underneath other than the level sensor.
Leaks were either the pump/level sensor seals or a split seam.
Never anthropomorphise computers. They hate that.Expansion Tank leak
Sorry, You've got the wrong tank. I'm talking about the Anti Freeze expansion tank to the right of the engine bay as you look at it. I've had the tank out and in the centre of the bottom there is some kind of short pipe which, when refitting, fits into a grommet in the bottom of the expansion tank holder.
The coolant seems to be coming from there. I thought that there me be another pipe from there to somewhere else but I cant see one.
Gordon
The coolant seems to be coming from there. I thought that there me be another pipe from there to somewhere else but I cant see one.
Gordon
Expansion Tank leak
Found the problem. A pressure test revealed that the tank is cracked. New one ordered.
Gordon
Gordon
Expansion Tank leak
Doh 
I don’t know why I read ‘expansion’ as ‘screen wash! Sorry
We have seen lots of reports about the screen wash tank too, but not relevant to your issue.
I don’t know why I read ‘expansion’ as ‘screen wash! Sorry We have seen lots of reports about the screen wash tank too, but not relevant to your issue.
Never anthropomorphise computers. They hate that.
Expansion Tank leak
Engineers have trouble reading ….. we’re better with pictures 
Never anthropomorphise computers. They hate that.