Longer travel of brake pedal after system flushed
 

Hello all,

Flushed the system during the weekend and now the pedal has to go farther almost to the end for stopping.

During flushing, i had pushed the pedal to the bottom several times. Did i kill the master cylinder? Is there a way to check it? Is replacing it a DIY job?

Had changed all screws to Speedbleeder so i assume this is not air in system issue.

Thanks in advance for your help. Have a nice day.

John
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92 300E 4Matic 135,582 KM

Did the reservoir at the master cylinder ever go dry during bleeding?

Hi Kestas,

No, i'd siphoned off the old fluid then filled up the reservoir with fresh. And checked the level after bleeding one side.

First, check the master cylinder by stomping on the brakes with the engine at idle. If the brake pedal creeps to the floor under steady pressure, you need to replace the master cylinder. If it doesn't creep, then you still have air in the lines that need to be bled out.

I don't know if pushing the pedal to the bottom killed the master cylinder. Some report it can, so maybe that's what happened. I do it all the time though (I take my chances).

You might check all your Speedbleeders and make sure they are not leaking.

After switching to speedbleeders all was fine until my son found one of the rubber caps in the driveway. I thought "Uh Oh!".

Sure enough one of the bleeders had a very small leak. I had it replaced but the threads in the caliper were just slightly sloppy. I used some teflon thread tape and that snugged them up just enough and no more leaks.

glenmore
1991 300CE

92 model...

This car has ABS and hence it is recommended to pressure bleed.


Michael

Thank you all for the help.

I'll check those bleeders as Glenmore suggested.

Michael, does it mean i have to bring the car to a mechanic/dealer to do the pressure bleed since i don't have a pressure bleeder.

Have a good day, dudes.

Kestas, forgot to tell you that i tried with your suggestion right after work and the pedal does not go to the bottom. So i assume the cylinder is still fine. I'll crawl under the car this evening to see if there's leaking at the bleeders.

Thanks again to all.

If you got air in the abs part of the system -possibly.

The big thing pros have seen since pressure bleeding is you don't run the mc seals accross a section of the bore beyond normal travel. That's the area where all the crude accumulates and hence it can damage the seal(aka reduce MC life).

So, you've got nothing to loose- try again and if it doesn't bleed take it to a pro. Your using DOT 4 fluid correct?

Michael

not one but two !!
 

Both bleeders at rear are leaking; i remember that i had pressed the pedal a few times after seating each bleeder to ensure no more fluid was coming out from them. Maybe i was trying not to overdo the seating or some teflon tape should be used.

Tightened them a little more and refilled the reservoir with dot 4 fluid and hope the leaking is ended.

Anyway, what's the correct torque for the bleeder screw? Please advise.

Thanks and have a good day.

John

John,

Be gentle with the bleeder screws. The originals as well as the Speedbleeders are soft and don't take much to seat them. I overdid my originals and they came out slightly crushed. The reddish brown thread sealant on the Speedbleeders tends to come off easily so I added teflon tape and that solved the problem. My Speedbleeder Installation Notes says:

"When the Speed Bleeder bottoms out, tighten to 32-40 in-lbs torque (not ft-lbs!!!!)" "Don't over tighten"

glenmore
1991 300CE