E46 325ti Compact.... Brake fluid loss!!!

[miniblob]

Car drove perfectly on wednesday night, jumped in the car thursday morning and the traction/stability lights were on from startup - put my foot on the brake pedal and it gradually sank to the floor!!!!!
Looked in the reservoir and zero visible brake fluid!!!

So what happened there then???

Looks like I'll be having a look tonight or Sunday - guessing the easiest way is to put some cardboard under each corner, chuck some fluid in and pump the pedal?

I'm guessing there's a master cylinder near the reservoir - never looked around under this bonnet really!!!

Any tips, or likely places for failure???
(Just approching 157k!!!)

Cheers,
Rob.

[martauto]

Good job it happend before you started to drive !
To loose all the fluid you must have a massive outlet somewhere, I would be tempted to roll the car back by hand (if you can safely do so ) and you should be able to see something on the floor.Given the fact you dont mention any warning lights from before, it may be a recent happening.

Mart.

[miniblob]

Hi Mart,

There were def no warning signs before - didn't notice the fluid being low when I topped up the oil a couple of days ago, but could've easily overlooked it!

I have moved the car - the brakes do work, just about, so there must be a little fluid in there somewhere!!!
It was during torrential rain though, on my sloped drive, so no evidence of the fluid loss, that I could see - though I wasn't keen to roll around in the puddles looking!!!

Yeah, was pretty lucky - I often drive enthusiastically and my routes are usually a lot of national limit A roads, fast B roads and country lanes, so could've easily ended in the scenery!!!

[miniblob]

Interestingly, just wondered if the clutch uses the same reservoir on these?

Had no problems getting it in gear and moving it around, thankfully - it was blocking my other car in!!!

[martauto]

Interestingly, just wondered if the clutch uses the same reservoir on these?

Had no problems getting it in gear and moving it around, thankfully - it was blocking my other car in!!!

I had a 318ti and that sort of rings a bell, check out the oem site to see, could be there?
Just had a look and I cant find a reservoir for the clutch master cylinder.
May be ??

Mart.

[miniblob]

Would say it could be the clutch slave cylinder, (had plenty of those fail on me in the past!), but why would the clutch work and the brakes fail???

Guess I'll have to crawl under and have a look!!!

[martauto]

Why ? maybe you just got lucky this time I dont know but it points in that direction dont you think?
Check out for fluid in the drivers footwell for the master.

Mart.

[Brianmoooore]

There will be small dividers in the bottom of the reservoir to ensure that one of the brake circuits still has some brake fluid after a major leak, to ensure that the car can still safely be brought to a halt. The circuit with the leak will be that which is fed from the section that is completely empty of fluid, so that will narrow it down a bit.
Having said that, a leak as bad as this should be fairly easy to spot.

[miniblob]

Had a little bit of old brake fluid knocking about and that was all I needed!!!
Rear right brake line has given up - just above the flexi hose, so doesn't look like something I want to do on the drive!!!
Need to drop the tank, etc, from what I've seen online!!!

Bugger - this bargain motor is getting expensive!!!

[Brianmoooore]

There's no reason why a replacement hard brake line has to run exactly where the old one did, as long as it isn't in danger of being damaged by something that moves and is adequately fixed in place.