what's this sound.....

[Mimmer]

when i drive my car it will make this random pump sound like its trying to put air .. does go away but does come back on at random....
its pretty loud and you can hear it from outside as well if door is closed.... sounds like its coming from front driver side but i dont know if this is below the wheel or like from the engine bay...

please help!

[Bartledoo]

Sounds like the brake boost pump. Have you spilled brake fluid around the brake fluid reservoir recently?

[Mimmer]

Originally Posted by Bartledoo

Sounds like the brake boost pump. Have you spilled brake fluid around the brake fluid reservoir recently?

I did change my pads n rotors recently. But didn't mess with fluid or see anything spill.... should I check engine see if anything like came out from brake fluid area?

[Bartledoo]

Originally Posted by Mimmer

I did change my pads n rotors recently. But didn't mess with fluid or see anything spill.... should I check engine see if anything like came out from brake fluid area?

Yea, you should look for moisture around the reservoir and shine a flashlight under the reservoir to see if the vacuum sensor is wet. Brake fluid will fry that sensor, causing the pump to run a lot. If you pushed all four caliper pistons back to replace thin pads, without removing some fluid (especially if the reservoir was at the upper fill limit), there is a good chance you overflowed the reservoir.

[Mimmer]

yeah i did need push the pads back to replace it, so the sensor then needs to be replaced if wet? is that the square black part? do i need remove any brake fluid now or just replace the sensor?

https://www.fcpeuro.com/products/bmw...05#description

im trying figure out how to go about replacing the part there been no video or anything visually helpful. if you have anything would be great!

[Mimmer]

Is it the black unit bottom? That is replace. Does the sensor sit right under the fluid ?

I did noticed moisture and even too cap felt like it was leaking .... not sure though how'd get on this part but I'll give it a try to replace.

[Bartledoo]

Originally Posted by Mimmer

Is it the black unit bottom? That is replace. Does the sensor sit right under the fluid ?

I did noticed moisture and even too cap felt like it was leaking .... not sure though how'd get on this part but I'll give it a try to replace.

Yea it looks like it overflowed on your sensor. we are all unsure why BMW put the sensor under it like that. You'll likely have an error code for it if you use a legit scanner. This is actually very common. The cap will not stop the fluid from overflowing if the caliper pistons are pushed back forcing it out.

[Mimmer]

do i need to remove any fluid you think? or just replace the sensor?

[Redd]

If your fluid isn't above max you're fine.

[Mimmer]

I see the word max but no line ... any way to read this best?

[Bartledoo]

Originally Posted by Mimmer

I see the word max but no line ... any way to read this best?

This line is to the left of the word in your first photo.

[Mimmer]

this that the part i need replace from my pic? the black piece? from pic 1

[Bartledoo]

Originally Posted by Mimmer

this that the part i need replace from my pic? the black piece? from pic 1

https://www.turnermotorsport.com/p-6...uine-bmw-part/

This is the sensor that gets fried. I can't see it in your photo, but I don't remember any other sensor being directly under the reservoir, so I'm pretty sure that wet connector is connected to it. Just check to be sure though. I'd recommend also scanning to futher verify, since the sensor isn't cheap. You don't actually have to replace the hoses, it just all comes as a single unit. If you're clever with a teleacoping magnet and long needle nose pliers you can replace just the sensor in 15-20 minutes. If not, it could take you hours.

[Redd]

Do search. You can get just the sensor for around $20. It's the same as Z4 MAP sensor I think.

[Dpc2u]

Originally Posted by Redd

Do search. You can get just the sensor for around $20. It's the same as Z4 MAP sensor I think.

^ What he said. Different application, but same sensor. Otherwise you have to buy the whole assembly with the lines.

https://www.fcpeuro.com/products/bmw...or-13628617097

[Mimmer]

Okay one in green that the line read the fluid?

One in red circle is that the sensor to replace ? If you looking in the app, you need click image enlarge it to see the whole image

[Bartledoo]

Originally Posted by Redd

Do search. You can get just the sensor for around $20. It's the same as Z4 MAP sensor I think.

Originally Posted by Dpc2u

^ What he said. Different application, but same sensor. Otherwise you have to buy the whole assembly with the lines.

https://www.fcpeuro.com/products/bmw...or-13628617097

Man where were you guys when I did this. Could've saved me a few $.

[Mimmer]

Updated sensor replaced fixed it. 👌 hope this helps others I know there few forums same thing I ran into

Note self. If you do brakes like pads replacement with new ones. Remove or check the brake fluid in the tank.

[Redd]

I hope you cleaned whatever brake fluid leaked into the car. Brake fluid is caustic and will damage paint and cause rust.

[Mimmer]

Yeah I'm just making sure I keep eye if it continue to leak anything out.

Planning put some foam strip tape see if it catches anything and remove it later.

This is my new level verse old.

Hard see but when I opened up the cap it was already hitting the top .... so I removed like 40 mm?
Even when I removed cap fully it was sitting pretty high ... so I think the new level is much better in pic 2

[Redd]

As long as you're near the Max mark you're fine. The Min mark is quite far down.

[Mimmer]

Yeah it's setting right below the max down arrow triangle. I didn't get before hand but I think it was at the top of the top triangle which was to much ...?