'84 300sd brake bleeding issues - PeachParts Mercedes-Benz Forum

74baja · #1 12-26-2011, 01:33 PM

Hi all,

I just finished installing rear shocks and springs, along with new brake hoses on all 4. I am now trying to flush/bleed the system. I have 2 quarts of DOT4 and a mityvac. I started on the driver's front, and am working my way away from the master cylinder. I noticed that whenever I top off the reservoir, it seems to only fill the rear of the reservoir ( i can see the fluid at the rear, but not on the front.) Is this normal?

Thanks,
Jack

74baja · #2 12-26-2011, 03:38 PM

bah, nevermind. just have to fill it a lot.

hangit · #3 12-26-2011, 03:45 PM

It was always my understanding to begin bleeding the brakes at the farthest wheel away from the master cylinder, right rear, left rear, right front and finally left front. JMTC.

John

toomany MBZ · #4 12-26-2011, 03:47 PM

^ Agreed, start from the furthest caliper away.

tangofox007 · #5 12-27-2011, 11:08 AM

Quote:

Originally Posted by hangit

It was always my understanding to begin bleeding the brakes at the farthest wheel away from the master cylinder, right rear, left rear, right front and finally left front.

I suspect that that recommendation dates back to an era when all four wheels were on the same hydraulic circuit. In the case of split systems, how is bleeding one circuit going to affect another? Even on the rear shared circuit, why is it going to matter? How is removing air from the "short" circuit going to introduce air into the "long" circuit?

vstech · #6 12-27-2011, 11:12 PM

a mityvac is a poor way to bleed the brakes on these cars. (heck, it's likely a poor method on any car!) Motive power bleeding is WAAAAAY simpler, more effective, and just a joy all around.
also, you can build your own bleeder from a cheapo pump up sprayer...

74baja · #7 12-28-2011, 03:59 PM

I did learn that the mityvac doesn't work well. I basically ended up doing the old pedal pumping method. The brake pedal is solid now, and it stops well. However, I have a slight suspicion that my driver's side rear brake might be dragging. I thought it felt sort of strange (hard to tell if that's the case) and with the rear seat still out, I can hear a circular saw like sound from that corner of the car at 25mph+. I drove for a few miles and got out to feel the wheels a few times, and never noticed any real heat though. I'm going to jack the wheel up and check by hand, but are there any other ways to tell for sure?

Thanks

toomany MBZ · #8 12-28-2011, 05:46 PM

Can you spin the tire when it's up in the air? You'll have some resistance, but you should be able to spin it.

vstech · #9 12-28-2011, 08:43 PM

Quote:

Originally Posted by 74baja

I did learn that the mityvac doesn't work well. I basically ended up doing the old pedal pumping method. The brake pedal is solid now, and it stops well. However, I have a slight suspicion that my driver's side rear brake might be dragging. I thought it felt sort of strange (hard to tell if that's the case) and with the rear seat still out, I can hear a circular saw like sound from that corner of the car at 25mph+. I drove for a few miles and got out to feel the wheels a few times, and never noticed any real heat though. I'm going to jack the wheel up and check by hand, but are there any other ways to tell for sure?

Thanks

this sounds like the brake shield is bent, or the swaybar link is broken...