2010 SL63 AMG, 2001 SL500, 2012 Corvette Z06, 2013 Lexus RX350, 2012 Cadillac CTS Coupe, 2015 Ram Joined
Nov 21, 2009 · 491 Posts
Discussion Starter · #1 ·
Mar 21, 2015 I'm planning to use a pressure bleeder do flush my brake fluid. All the general instructions I can find for pressure bleeders call for 10-15psi, but somewhere on this forum 2 bars (29psi) is stated. Should the pump pressure really be double what is normally done, or is this some confusion between relative (to surrounding atmospheric
pressure) and absolute pressure? 97 E-420 (180K miles), 97 SL500, (93K miles) 2015 GMC Sierra Denali 2500HD CC/SB/4x4 Duramax(55K) Joined Sep 30, 2008 · 4,654 Posts
MB work documentation calls for 2 bar on vehicles with ABS/ASR etc. you are correct it is about double what is commonly called for, but that "common" 15psi originated long before ABS came about. The increased pressure is apparently needed to insure the ABS unit is properly bleed. Now, all that said, my experience is that IF you have NO air in
the lines, 15 psi SEEMS to work. But using the 2 bar as recomended is probably more appropriate. 2010 SL63 AMG, 2001 SL500, 2012 Corvette Z06, 2013 Lexus RX350, 2012 Cadillac CTS Coupe, 2015 Ram Joined Nov 21, 2009 · 491 Posts
Discussion Starter · #3 · Mar 21, 2015 Thank you. I will put this knowledge to good use.
1996 SL500, 2000 E430, 2011 E350 Joined Mar 9, 2013 · 5,044 Posts
On my 300E also with ABS I got away with as little as 10 psi - as long as you see fluid coming out the bleed hose from the caliper - as E420 said as long as you know you are starting from an airless system. I once had to much pressure on the W124 - 30 or more and found that the brake reservoir popped off - spraying brake fluid everywhere. What a mess.
I bled the SL500 with 10-15 lns last time... 99' E320, 00' E320, 03' E320T, 05' C230K Joined Nov 2, 2010 · 5,006 Posts
On my former 260E, I used 1 bar (14.5 psi) without any issue. On my C230K, CLK, and Accord, I use 1.5 bars (21.7 psi). Its a slow bleed and as mentioned is ok if there is no air in the line. Really afraid to take it to 2 bars (29 psi). Some people say to have the ignition on, but I didn't find any difference with the bleed rate. I also installed a tire air valve stem on my bleeder. Makes it a snap to pressurize with my compressor which I use for my vacuum evacuator to empty the master cylinder. 2010 SL63 AMG, 2001 SL500, 2012 Corvette Z06, 2013 Lexus RX350, 2012 Cadillac CTS Coupe, 2015 Ram Joined Nov 21, 2009 · 491 Posts
Discussion Starter · #6 · Mar 24, 2015 ... I once had to much pressure on the W124 - 30 or more and found that the brake reservoir popped off - spraying brake fluid everywhere. What a mess.... I was wondering about that. The reservoir is just held in place by the rubber bushings, because it is not normally under any pressure. I'm thinking about
clamping down the reservoir with a big hose clamp or cable ties while I do the bleed, regardless how much pressure I use. Even if the tanks stays put, I think too much pressure could potentially push fluid past the rubber. 1988 300e 75 300d 74 450sl Joined May 6, 2014 · 764 Posts
i use about 15 psi with mercedes the master cyl adapter screws on and has nothing to hold resivior. the adapter for american cars has a chain that goes around the master cylinder to keep lid on 1996 SL500, 1980 300CD, 2019 Sprinter 3500 Joined Nov 8, 2007 · 67 Posts
Want to pressure bleed brake fluid.
 99' E320, 00' E320, 03' E320T, 05' C230K Joined Nov 2, 2010 · 5,006 Posts What pressure do you bleed brakes?All you have to do is fill the power bleeder with a brake fluid of your choice, pressurize it to about 15 psi, then go and crack your caliper bleeder screw. The pressure is enough to push the old fluid out, no pedal pumping required. I like to repump it a few times per corner to get out as much fluid as possible.
How much brake fluid Do I need to bleed my brakes?Head down to the auto parts store or dealer's parts department to pick up the correct fluid before you start working on the brakes. Good-quality brake fluid isn't expensive; you'll probably need two or three 12-ounce cans to bleed the system.
How many times do you pump brakes when bleeding?Instruct the assistant to "apply." The assistant should pump the brake pedal three times, hold the pedal down firmly, and respond with "applied." Instruct the assistant not to release the brakes until told to do so. Loosen the bleeder screw with a brief ¼ turn to release fluid into the waste line.
Do you have to bleed all 4 when braking?Answer provided by. Yes, many car experts recommend that you bleed all four brakes once you open one of the brake lines to replace a caliper or do other work. However, this is not a hard-and-fast rule, particularly if the brake line you are having work done to is independent of the other lines.
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How much psi do I need to bleed my brakes?
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