DSC pressure sensor

[eacmen]

1. same part number
2. sensors do not come with the MC and the MC is expensive
3. I think its worth it given the age of these cars, but really depends how budget strict you are.

[mjweimer]

Do E46 master cylinders commonly fail? I've not heard of many and if you have a record of regular fluid changes, I would think replacing the master is throwing away $$$.

TIS procedure for a LHD Mk60 attached for reference. There is zero space to remove the clutch hydraulics supply line from the reservoir and it is difficult to get rags below the master to catch brake fluid so I decided on a different approach and loosen up the E-box.

I pulled all the stuff out of the E-box, removed the 4 screws that hold it to the firewall from under the dash, removed the plastic "wall" that sits next to the hood strut, clipped the two small wire ties on the harness that runs towards the LF headlamp and gently lifted and rotated the E-box housing. There is just enough slack in the main harness that runs through the firewall to allow the box to be rotated and lifted past the windshield cowl. Reaching underneath, I was able to unplug the connectors easily and remove each sensor with a 27mm deep-well socket. With the right combination of 3/8" drive extensions I was also able to torque these to the proper spec (25Nm -> 18 ft-lb -> 221 in-lb). I found a cheap 27mm deep-well at AutoZone for $10.


DSC Mk60 pressure sensor.pdf

[Maxhouse97]

Thanks guys

[elbert]

I pulled all the stuff out of the E-box, removed the 4 screws that hold it to the firewall from under the dash, removed the plastic "wall" that sits next to the hood strut, clipped the two small wire ties on the harness that runs towards the LF headlamp and gently lifted and rotated the E-box housing. There is just enough slack in the main harness that runs through the firewall to allow the box to be rotated and lifted past the windshield cowl. Reaching underneath, I was able to unplug the connectors easily and remove each sensor with a 27mm deep-well socket. With the right combination of 3/8" drive extensions I was also able to torque these to the proper spec (25Nm -> 18 ft-lb -> 221 in-lb). I found a cheap 27mm deep-well at AutoZone for $10.

Hmm, I think I'm gonna have to try this.
I tried the 50skid technique by trying to pull the master cylinder from the brake booster. However, I can't get it far enough away for access -- one of the MC's mount tabs is hitting the hard lines coming from the Mk60, even after loosening the Mk60's mounting screw.
Hope I didn't mess up the brake booster with all the pulling and twisting...

[elbert]

OK, I just finished this job. It wasn't terribly difficult, but it certainly was annoying.
Here are some follow up notes on my experience replacing these sensors (car is a 2004 with the Mk60):

1. Sensors
- I strongly recommend you buy only genuine BMW sensors from a reputable source (amazon and ebay are not reputable). Mk60 swaps into other cars is fairly common, and there are documented cases of fake or aftermarket sensors blowing apart, causing complete loss of brake pressure. The cheap copies take fake Ate bodies and epoxy new sensors into place, and this epoxy bond fails.
- Sensors front and rear are the same

2. You may need to remove your intake
- You need to completely remove the plastic plate that separates that little compartment from the rest of the engine bay
- I had to also remove my CSL intake to do that since it was a tight fit. It does make things much easier to clean up because...

3. I had to disconnect the hard lines
- I ended up needing to disconnect the hard lines from the master cylinder. The front sensor connector can't be removed because its path is blocked by the hard line.
- 11 mm wrench
- Just accept the fact some brake fluid will spill. I shoved a bunch of paper towels under the master cylinder, but there was still some that made it past the towels.
- There is some metal body work underneath that acts like a tray (it has a drain). I used soapy water to flush, followed by a couple gallons of water the rinse. With the intake out, it is easy to dump water.

4. Removing e box helped a little
- I tried removing the ebox. I wasn't able to get it to move as much as mjweimer did, but being able to move it aside made access a bit easier.
- You need to remove a blower fan that has 3 phillips screws first, then you can find the 4 bolts that secure the ebox
- I was worried putting the ebox back into place would be difficult, but its shaped to match the firewall, so it is easy to position
- Oh, one other thing: make sure the put the driver's seat as far back as possible before you unplug everything. It will save on some contorting.

5. Bleeding brakes
- You will need INPA to cycle the abs. There was a ton of air in there.

Hope someone finds this helpful.