Quote:
Originally Posted by cdb95z28
The GM service manual does have info on flushing and bleeding. acdelcotds.com will get you access to GM's info. $22 for a 3 day subscription. You can copy as many pages on there as you can in 3 days. And that is not limited to just one VIN/vehicle. I did many of my GM vehicles when I did it.
Most of us track guys pressure bleed. I use the Motive Bleeder 0108. But I do not put fluid inside the bleeder reservoir. I keep an eye on the master level. Do not run the master dry!
There is a specific bleed order that is not like the old RR/LR/RF/LF.
The proper sequence is:
RR/LF/LR/RF
The reason it is different because of where the ABS module is located.
Pressurize the master to 25-30PSI.
Gravity bleed is not a good way to bleed these complex circuits.
There is an ABS bleed procedure. This will flush out the old fluid from within the ABS module. It can make a positive difference in the pedal feel if it is performed. You need the proper scan tool though, to do this. I have a Foxwell NT630 Plus, it works great. Look on Amazon. The ABS sequence that the scan tool performs is controversial but I have used two different scan tools and they do it the exact same way the GM Tech 2 does it. Just follow the scan tool's procedure no matter the questionable sound sequence. I track my '22 SS 1LE and previous '14 SS 1LE and have done a rediculous amount of bleeds over the past 12 years.
DOT3 is acceptable for just street use but buy a quality fluid. DOT4 gets you a higher dry and wet temp boiling point but note that DOT4 fluid absorbs moisture at a faster rate than DOT3.
PDF file on pressure bleeding:
Attachment 1174715
ABS bleed:
Attachment 1174716 |
Very strong emphasis on do not let the master cylinder run dry.
I said gravity fed system but i didn't clarify what i ment. Gravity fed to the master cylinder reservoir. Basically a glorified funnel just to get more volume in the master cylinder. I force bleed with the pedal but i usually have someone nearby to work the pedal while I'm at the valves.
Personally I'm not a fan of force pump bleeding unless i just need to. The master cylinder reservoir wasn't designed for pressure so i don't like putting pressure into it. Similar to pulling a vacuum on the cooling system, people do it but i don't.
A lot of times if I'm not flushing but just bleeding, i will just run a hose from the brake caliper back to the reservoir and open the valve and just pump the fluid through. The air will get caught in the reservoir.