How do you check the brake fluid level? - The Unofficial BMW M5 Messageboard (m5board.com)

KevinM · 13th November 2008, 08:12

So my DSC light came on out of the blue tonight. No other warning lights were illuminated and no codes came up with my Peake reader. A quick search suggests wheel ABS sensors, fuses, and low brake fluid level to start.

Fuse 17 was a bit out, and when I pushed it back in the light went out. So I think that is the cause. However, my original brakes (pads and rotors) are at 57K miles so I thought I'd check the brake fluid level anyway (I should point out I had a brake flush a few years ag0 as part of the BMW maintenance program, then had Inspection II in January 2008). So the manual tells me the reservoir is under the driver's side air cabin filter housing, but does not state how to access it. I found many posts alluding to taking out the cabin filter housing but none that actually describe how to do it (maybe I missed the posts, but I did try).

So, just out of curiosity, how does one actually check the brake fluid level?

Thanks in advance.

razahyde · 13th November 2008, 08:27

the reservoir is under the driver side cabin filter. rest should be self explanatory.

jaj · 13th November 2008, 08:39

Quote:

Originally Posted by KevinM

So the manual tells me the reservoir is under the driver's side air cabin filter housing, but does not state how to access it. I found many posts alluding to taking out the cabin filter housing but none that actually describe how to do it (maybe I missed the posts, but I did try).

So, just out of curiosity, how does one actually check the brake fluid level?

Thanks in advance.

Open the hood. The cabin air filter is that black box right up against the firewall at the bottom of the windshield. The whole box comes out to reveal the brake master cylinder below it.

Pop the metal spring clip that runs along the front edge of the filter box and lift off the lid. You don't need to take the filter out.

Undo the connector to the switch that sits just in front of the box - the switch comes out with the box, the wire doesn't.

Pop the three clips along the center edge of the box where the snorkel enters it - just pry up gently with a flat screwdriver blade and they'll let go. When all three have popped, the ring just slides back about 1/2 inch, releasing the snorkel's grip on the housing.

The housing is now retained by a metal spring clip that slips down over a black post at the front near the switch you disconnected. Just squeeze the spring wires together and lift - the whole filter housing will lift up and out.

Reassembly is the reverse of removal. The first time it looks a little daunting but after you've done it a few times it takes less than a minute.

DouglasABaker · 13th November 2008, 14:21

And as a side note, if you'd had a fluid flush then the level of your fluid isn't likely to tell you anything about whether your brakes need to be replaced anyway - they refilled it when it was flushed.

Lastly, remember that the sensor for pads is only on 1 pad per axle. Any or all of the other 3 could still be worn out due to a sticking caliper, etc. Take the wheels off and look if you want to be sure about pad life.

d-

KevinM · 13th November 2008, 20:44

Jaj, thanks!! And Doug, thanks for the comments. I do need to check the brake pads but don't have lift or a jack so I guess I'll need to take it to a shop

.

Kent Bullis · 14th November 2008, 01:26

Should the fluid be at the full line with the cap on and the level sensor down in the fluid, or with the cap off and the level sensor removed? I recently had to remove some fluid when I put new pads on and wasn't sure where my level should be when I was done.

DouglasABaker · 14th November 2008, 03:14

Cap on, sensor in...

d-

Redneck M5 · 14th November 2008, 03:18

There also a warning switch to tell you if the hydraulic fluid is too low.

CSBM5 · 14th November 2008, 04:07

Quote:

Originally Posted by KevinM

Jaj, thanks!! And Doug, thanks for the comments. I do need to check the brake pads but don't have lift or a jack so I guess I'll need to take it to a shop

.

Dealerships (and maybe your indy) have a little tool that you can just stick through an opening in the wheel and measure the brake pad thickness...just takes a second on each corner. I think it reads pad thickness in mm.