Brake fluid exchange procedure

[jbawden]

A brake fluid exchange has been part of my DIY wheelhouse for years, but this is my first vehicle with a 'brake by wire' system. The owners manual says there is a specific procedure detailed in the service manual and wondered if anyone has reviewed/downloaded that section? About the only thing the owners manual states is the battery should be disconnected. I may or may not track the car, but definitely not waiting 5 years (interval in the OM) to change the fluid.

 

[MatthewAMEL]

A brake fluid exchange has been part of my DIY wheelhouse for years, but this is my first vehicle with a 'brake by wire' system. The owners manual says there is a specific procedure detailed in the service manual and wondered if anyone has reviewed/downloaded that section? About the only thing the owners manual states is the battery should be disconnected. I may or may not track the car, but definitely not waiting 5 years (interval in the OM) to change the fluid.

I just went through this in prep for my 1st track weekend.

It is a complete PITA and beyond the means of a average DIY'er.

Not only is it a 'brake by wire' system, but there are multiple pumps and sensors in the system that the computer tracks. It's impossible to use the old school 2-man pedal pump to bleed and for a flush, you have to put the computer into a diagnostic/service mode.

After reading the document, I took mine to the dealer who swapped for SRF for $200.

I spoke with the tech who worked on my car and asked him if he had any idea how much $ to buy the tools recommended in the service manual. He said probably around $5000 and you would need a current subscription to the software.

I hope someone smarter than me can figure out a way past this.

I have the J57 (CCB) brakes.

 

[jbawden]

Thanks for that Matt. I long ago abandoned the "pump, hold, release" 2-person strategy when I added a simple motive products pressure bleeder to my tool kit. Now with BBW system, the brake pedal is no longer a part of bleeding or fluid changes. But, the fluid portion appears to be like any other modern brake system.

After a quick read all I see that would require a special tool is GDS to deactivate brake boost system, but disconnecting the battery would do the same thing. For a simple fluid change, I don't see anything that would be different than how I've been doing it.

I think too we can lean on the C8 crowd as they are using a similar/same? system. To that end brake pad changes are critical to disconnect the battery as opening a door can activate the self-test system and if you have a pads removed from a caliper when that happens it might ruin your day.

 

[Mbar]

Interesting. I just disconnected the battery and did old fashioned 2 people bleed. No issue at the track.

 

[Joszer]

I remember watching a review on the Blackwing and one of the GM engineers said that the brake pedal IS hooked up to the system Incase of an electronic failure.

I've always used a simple Brake Bleeder tube with a check valve that hooks up to the bleeders on the calipers. I'm hoping this will work.

I don't trust the GM and Cadillac dealers local to me. When I dropped off my 4BW for the free first oil change, they had to wait for 1 tech to stop what he was doing to drive my car into the bay for the change becaise no one else in the dept knew how to drive a manual.

I'm gonna have to figure out who to take it to for the track alignment and rear diff for my first track day.

 

[MatthewAMEL]

So…I can safely ignore the part of the document that says if you open the master, you have to flush the system?

Was just a bit shocked by all the warnings and admonitions in the service manual.

I use a Mityvac for bleeds. I attach to the bleeder screws and vacuum fluid. No reason that process won’t work?

I have done lots of work on all my cars for years, for some reason (I think it’s the price tag) working on the BW has me a bit paranoid. I will admit oil and diff fluids were a no brainer.

 

[jbawden]

I read the note about the system being opened and requiring a bleed as referring to the high pressure lines, not the reservoir (@MatthewAMEL I'm not sure if that is what you're take is). I think lawyers have slowly crept into service manuals and more and more notes like this are creeping in.

I totally get the price of the car making you wobbly about maintenance beyond the basics. A service manual investment is a critical component for DIY on this one for sure.

I think a Mityvac will work, but I use a Motive Products power bleeder. The difference between this and the GM recommended tool is the GM tool uses a bladder the keeps the fluid out of contact of the pressure air. I get why this is important (particularly if you're using shop air), but I start with a very clean powder bleeder, new fluid, and I'm careful about working in a clean environment. I clean the bleeder with denatured alcohol when done and make sure its spotless before I start.

Link below for the tool I use, but I don't know if any of the adaptors I have will work (haven't checked) but will report when I do.

0108 - Late Model GM Power Bleeder

Solo‐bleed GM brakes (’92+) with the 0108 Power Bleeder Kit: 2 qt corrosion‐proof reservoir, twist-on 1108 adapter & 4 ft tubing for fast, mess-free service.

www.motiveproducts.com

 

[MatthewAMEL]

I read the note about the system being opened and requiring a bleed as referring to the high pressure lines, not the reservoir (@MatthewAMEL I'm not sure if that is what you're take is). I think lawyers have slowly crept into service manuals and more and more notes like this are creeping in.

I totally get the price of the car making you wobbly about maintenance beyond the basics. A service manual investment is a critical component for DIY on this one for sure.

I think a Mityvac will work, but I use a Motive Products power bleeder. The difference between this and the GM recommended tool is the GM tool uses a bladder the keeps the fluid out of contact of the pressure air. I get why this is important (particularly if you're using shop air), but I start with a very clean powder bleeder, new fluid, and I'm careful about working in a clean environment. I clean the bleeder with denatured alcohol when done and make sure its spotless before I start.

Link below for the tool I use, but I don't know if any of the adaptors I have will work (haven't checked) but will report when I do.

0108 - Late Model GM Power Bleeder

Solo‐bleed GM brakes (’92+) with the 0108 Power Bleeder Kit: 2 qt corrosion‐proof reservoir, twist-on 1108 adapter & 4 ft tubing for fast, mess-free service.

www.motiveproducts.com

Thanks. I used a Motive in the past, but switched after a few incidents where the master was over-pressurized and the fluid wound up all over the floor.

So, with the addition of removing the battery cable, brake service should be like all the others I have done. I’ll give it a shot before my next track event (Daytona on 4/20).

 

[poor-sha]

I also did the disconnect the battery and use a motive to flush my brake fluid.

The brake bleed procedure in the C8 service manual is really bonkers too. It has you doing a normal bleed with pressure and then doing it by compressing with a vice grip specific pistons on each caliper in a specific order - then repeating the process four times.

 

[Neveready]

Some of what is mentioned here is absolutely shocking and ridiculous. And I thought zee Germans were the authority on over engineering and needless labor techniques.

This sort of information makes me cringe at doing regular maintenance that I thought I had mastered a 100 times over. What's next, do I have to pat my head 3 times while rubbing my stomach in a bidirectional motion before or after I change the pads?

 

[Daijoubu]

There is another procedure in the Factory Service Manual for "Antilock Brake System Automated Bleed" and it requires the GM scan tool. This is the only way to truly flush ALL of the old fluid out, and get the new fluid in. It is able to run the ABS pump and valves to push the old fluid out to the caliper bleed screws. I asked my tech to thoroughly flush all the fluid by using up the entire bottle of SRF to make sure all the old stuff is out.

 

[poor-sha]

I believe you only need to do the ABS automated bleed if you somehow got air in the ABS pump. Conventionally wisdom seems to be to bleed what you can and if you want to flush out the ABS pump just go get in to ABS mode.

BTW, this is a subset of the C8 bleed procedure I was referring to:

 

[Daijoubu]

I believe you only need to do the ABS automated bleed if you somehow got air in the ABS pump. Conventionally wisdom seems to be to bleed what you can and if you want to flush out the ABS pump just go get in to ABS mode.

BTW, this is a subset of the C8 bleed procedure I was referring to:
View attachment 17330

Yes, you can do this, but it requires you to manually bleed the brakes, go drive the car. Find a slick enough surface and get up enough speed to get the ABS to activate, then come back and bleed the brakes again.

 

[Mbar]

I was never worried about a few ml of old fluid in the ABS. I was more worried about early stories of people having their clutch pedal dropping to the floor during a track event.

 

[poor-sha]

I was never worried about a few ml of old fluid in the ABS. I was more worried about early stories of people having their clutch pedal dropping to the floor during a track event.

The fix for that appears to be to follow the service manual procedure to bleed the clutch by puling a vacuum.

 

[Bourbonp]

Interesting. I just disconnected the battery and did old fashioned 2 people bleed. No issue at the track.

How much brake fluid is necessary for a brake flush? I intend to use Castrol SRF.

 

[almazing]

Is a gravity bleed possible with the Blackwings? I don't have assistance, but I certain do have several hours to kill on a Saturday, so time is not an issue. I just need to know if the fluid will flow on its own.

 

[Carguyshu]

How much brake fluid is necessary for a brake flush? I intend to use Castrol SRF.

1.5 bottles

 

[strohw]

Is a gravity bleed possible with the Blackwings? I don't have assistance, but I certain do have several hours to kill on a Saturday, so time is not an issue. I just need to know if the fluid will flow on its own.

You could try it and see. Ideally you should be using a pressure bleeder like a Motive.

 

[almazing]

You could try it and see. Ideally you should be using a pressure bleeder like a Motive.

Yea I had one in the past, but lost it at some point. I will likely buy another one anyway. Is the cap 0108/0118?