Identify empty tank under hood ?

[DanSanDiego]

Can anyone help me identify this empty tank under the hood of my '03 3.0i? See photo. It is under the hood, way up by the windshield and under a plastic cover. It has a max and min line on it, but it is empty.

[rayxi]

Brake fluid expansion tank. Better add some and look for leaks.

[TiAgX5]

Brake/clutch fluid master cylinder.

[DanSanDiego]

Thank you. I will fill it immediately. I thought that it was odd to have an empty tank under the hood (but I wasn't sure why it was hidden behind a cover next to the windshield).

If I'm lucky, then this will also explain the 5 drops of dark fluid on my floor each night. When I did the oil filter housing gasket change this weekend the brake light came on at first startup after the procedure. I started it a few more times and the light went away. I thought it was just a result of the battery being off overnight and didn't pay attention to it. Now I know that it was an early warning to my condition.

[TiAgX5]

The systems fluid needs to be replaced every 2 years, may be a good time to do it.

[TechWrench]

Where under the vehicle are you seeing the fluid drops. There is a known issue with the metal brake lines along the driver side frame rail rusting out and leaking. If you have lost that much fluid, it indicates a serious leak problem. And, if it is the brake lines, be prepared for a BIG bill, I know because I just went through it. The mechanics at dealer said it is becoming a constant thing with the X5's needing brake lines replaced.

[ECS Tuning]

Have you noticed any problems with your breaking? Regardless they will probably feel a lot better once you add more fluid to the system. HERE is a link to our selection of fluid that is compatible with your X5 3.0.

ECS Tuning

[DanSanDiego]

False alarm. At lunchtime I got all the way to AutoZone (I wouldn't normally go there, but this was an emergency), checked the brake fluid level (never actually opened it before) and it was full all the way to the cap. That is why I wasn't able to see a line on the side.

So that is good news. I was really nervous.

[TiAgX5]

You will still want to replace the fluid. I replaced mine with the Ate SuperBlue Racing DOT 4, the stuff is reasonably priced and has a higher boiling temp then most other DOT4s.

[Icer006]

I use ATE TYP200. Same as SuperBlue, DOT4, except no blue dye!
Motul RBF660 is a good one too.